Honeywell E3Point User Manual

Download

Page 1

GasBook

Honeywell Gas Detection

Page 2

Introduction

The Gas Book is intended to offer

a simple guide to

anyone considering the

use of xed and portable

gas detection equipment.

The aim has been to provide a complete

and comprehensive introduction to the subject– from detailing the principles of

detection that different devices employ to

providing information on certications

and application suitability.

A diverse variety of applications and processes increasingly involve the use and manufacture of highly dangerous substances, particularly

ammable, toxic and Oxygen gases.

Inevitably, occasional escapes of gas occur, which create a potential hazard to the industrial plants, their

employees and people living nearby.

Worldwide incidents, involving

asphyxiation, explosions and loss of

life, are a constant reminder of this

problem.

www.honeywellanalytics.com / www.gasmonitors.com2 www.honeywellanalytics.com

www.honeywellanalytics.com / www.gasmonitors.com

n most industries, one of the key parts of any safety plan for reducing risks to personnel and plant is the use of early warning devices such as gas detectors. These can help to provide more time in which to take

remedial or protective action. They can also be used as part of a total, integrated monitoring and safety system which may include various other safety aspects including ﬁre detection and emergency process shutdown. Gas detection can be divided into two overriding categories; ﬁxed gas detection and portable gas detection. As the name might suggest, ﬁxed gas detection represents a static type of detection system for ﬂammable, toxic and Oxygen gas hazards and is designed to monitor processes, and protect plant and assets as well as personnel on-site.

Portable gas detection is designed speciﬁcally to protect personnel from the threat of ﬂammable, toxic or Oxygen gas hazards and is typically a small device worn by an operator to monitor the breathing zone. Many sites incorporate a mix of both ﬁxed and portable gas detection as part of their safety philosophy, but the suitability of which type to use will depend on several factors, including how often the area is accessed by personnel.

Page 3

Contents

Section Subject Page Section Subject Page

1 Introduction 2

2 Honeywell Gas Detection brands 4-5

3 What is gas? 6

4 Gas hazards 7

5 Flammable gas hazards 8 Flammable limit 9 Flammable gas properties 10-11 Flammable gases data 12-19

6 Toxic gas hazards 20 Workplace exposure limits 21 Toxic exposure limits 22-25 Toxic gases data 26-29

7 Asphyxiant (Oxygen deciency) hazard 30

8 Oxygen enrichment 31

9 Typical areas that require gas detection 32-35

10 Principles of detection 36 Combustible gas sensor 36 Catalytic sensor 36 Speed of response 37 Sensor output 37 Calibration 38 Infrared gas detector 39

Open path ammable infrared gas detector 40

Electrochemical cell sensors 41

Photo Ionised Detection (PID) 42

Chemcassette Comparison of gas detection techniques 43

11 Selecting gas detection 44-45

12 Maximising time and efciency 46-47

13 Communications protocols 48-49

14 Fixed gas detection from Honeywell 50-51

15 Portable gas detectors 52 Why are portable gas detectors so important? 54 Breathing zone 55 Typical gases requiring portable detection 55 Portable gas detector types 56 Operational modes of a gas detector 56 Features and functionality 57 Accessories 58 Alarms and status indication 59 Typical applications for portable gas detectors 60

Conned spaces 60-61

Marine 62 Water treatment industry 63 Military 64-65

Hazardous Material (HAZMAT)

emergency response 66

Oil and gas (on and offshore) 67

PID Information 68 Measuring Solvent, Fuel and VOC Vapour in the workplace environment 68-71 Maintaining portable gas detection 72 Reducing the cost of device testing 73 How to perform a manual bump test 73 Portable gas detectors from Honeywell 74-75

16 North American hazardous area standards and approvals 76

North American Ex marking and area classication 77

17 European hazardous area standards

and approvals 78-79

sensor 42

18 ATEX 80-81

19 Area classication 86-87

20 Apparatus design 88-89

21 Apparatus classication 90-91

22 Ingress protection of enclosures 92-93

23 Safety integrity levels (SIL) 94-95

24 Gas detection systems 96-97 Location of sensors 98-99 Typical sensor mounting options 100

Typical system congurations 100-101

25 Installation 102

26 Gas detection maintenance and ongoing care 106-109

27 Glossary 110-113

IEC Standards 82-83 Equipment markings 84-85

Page 4

Honeywell Gas Detection brands

At Honeywell Analytics our key focus is our customers. We believe that the evolution

of gas detection should be driven by the people using our equipment, rather than

engineers deciding the needs of industry. With this in mind, we listen to what our customers want, rene our solutions to meet changing demands and we grow as our

customers grow to ensure we are able to provide an added value service that meets

individual requirements.

Working with Industry… since the birth of gas detection

ith 50 years experience in the industry, we have been

inuential in gas detection since the very beginning.

Many of our historic products set new benchmarks

use and innovation. Today, our product lines have evolved to meet the requirements of diverse industries and applications, delivering comprehensive solutions designed to drive down the cost of gas detection, whilst providing enhanced safety.

for gas detection in terms of performance, ease of

Our Technical Support Centre and Product Application and Training

Specialists, eld engineers and in-house engineering support represent

some of the very best the industry has to offer, providing over 1,100 years cumulative expertise, allowing us to deliver local business support on a corporate scale.

4 www.honeywellanalytics.com / www.gasmonitors.com

Page 5

GAS

FACT

The word gas was

coined in 1650–60 by

J. B. van Helmont

(1577–1644), a Flemish

chemist. It comes from

the Greek word

for chaos.

W Technologies by Honeywell is a World leader in the gas detection industry with a strong commitment to providing customers with high performance, dependable portable

service and ongoing support.

We design, manufacture and market innovative portable gas detection solutions for a wide variety of applications and industries, with options to suit all budgets and hazard monitoring requirements.

Our comprehensive range includes options from single gas units that require no ongoing maintenance, to feature-rich multi-gas devices that deliver additional value-added functionality.

As a leading expert in the eld of portable gas detection, we provide customised on-site/eld based training to meet specic customer

needs and application support to assist customers with the selection

and integration of solutions that are entirely t for purpose.

When it comes to device care, we also offer cost-effective benchmark support and maintenance through our comprehensive approved partner network.

products that are backed up by exceptional customer

Delivering value added solutions at affordable prices for 25 years

BW Technologies by Honeywell was originally established in 1987 in Calgary, Canada. Over the last 25 years, we have been bringing innovative gas detection solutions to market that add value, enhance safety and help to reduce the ongoing cost of portable gas detection.

With ofces all over the World, and a diverse and talented team of

industry experts on hand to provide support to customers, we offer a large corporate infrastructure supported by locally focused teams that have a unique understanding of industry and applications as well as regional needs.

Page 6

What is Gas?

The name gas comes from the word

chaos. Gas is a swarm of molecules

moving randomly and chaotically, constantly colliding with each other

and anything else around them. Gases ll any available volume and due to the

very high speed at which they move will

mix rapidly into any atmosphere in which they are released.

Vehicle engines combust fuel and Oxygen and produce exhaust gases that include Nitrogen Oxides, Carbon Monoxide and Carbon Dioxide.

Different gases are all around us in everyday life. The air we breathe is made up of several different gases including Oxygen and Nitrogen.

Air Composition

The table gives the sea-level composition of air (in percent by volume at the temperature of 15°C and the pressure of

101325 Pa).

Name Symbol Percent by Volume

Nitrogen N2 78.084% Oxygen O Argon Ar 0.934% Carbon Dioxide CO Neon Ne 0.001818% Methane CH

2 20.9476%

2 0.0314%

4 0.0002%

Helium He 0.000524% Krypton Kr 0.000114% Hydrogen H Xenon Xe 0.0000087%

6 www.honeywellanalytics.com / www.gasmonitors.com

2 0.00005%

Page 7

Gas Hazards

There are three main types of gas hazard:

Gases can be lighter, heavier or about the same density as air. Gases can have an odour or be odourless. Gases can have colour or be colourless. If you can’t see it, smell it or touch it, it doesn’t mean that it is not there.

Flammable

RISK OF FIRE AND/OR EXPLOSION

e.g. Methane, Butane, Propane

Toxic

RISK OF POISONING

e.g. Carbon Monoxide, Hydrogen, Chlorine

Natural Gas (Methane) is used

in many homes for heating and cooking.

Asphyxiant

RISK OF SUFFOCATION

e.g.

Oxygen deciency. Oxygen

can be consumed or displaced by another gas

Page 8

Flammable Gas Hazards

Combustion is a fairly simple chemical reaction in which

Oxygen is combined rapidly

with another substance resulting in the release of

energy. This energy appears

mainly as heat – sometimes

in the form of ames.

The igniting substance is normally, but not always, a Hydrocarbon compound and can be solid, liquid, vapour

or gas. However, only gases

and vapours are considered

in this publication.

(N.B. The terms

‘ammable’, ‘explosive’, and ‘combustible’ are, for the purpose of this publication, interchangeable).

The Fire Triangle

The process of combustion can be

represented by the well known re triangle.

Three factors are always needed to cause combustion:

A SOURCE OF IGNITION

OXYGEN

FUEL IN THE FORM

OF A GAS OR VAPOUR

In any re protection system,

therefore, the aim is to always remove at least one of these three potentially hazardous items.

AIR

FIRE

FUEL

HEAT

8 www.honeywellanalytics.com / www.gasmonitors.com

Page 9

Flammable Limit

There is only a limited band of gas/air concentration which

will produce a combustible mixture. This band is specic

for each gas and vapour and is bounded by an upper level,

known as the Upper Explosive Limit (or the UEL) and a lower level, called the Lower Explosive Limit (LEL).

Limits of Flammability

TOO RICH

GAS

FACT

High levels of O2 increase

the ammability of materials

and gases – at levels such

as 24%, items such as

clothing can spontaneously

combust!

100% v/v gas 0% v/v air

t levels below the LEL, there is

insufcient gas to produce an

explosion i.e. the mixture is too

the mixture has insufcient Oxygen i.e. the mixture is too ‘rich’. The ammable range

therefore falls between the limits of the LEL and UEL for each individual gas or mixture of gases. Outside these limits, the mixture is not capable of combustion. The Flammable Gases Data on page 12 indicates the limiting values for some of the better-known combustible gases and compounds. The data is given for gases and vapours at normal conditions of pressure and temperature.

‘lean’, whilst above the UEL,

FLAMMABLE

RANGE

TOO LEAN

An increase in pressure, temperature or Oxygen content will generally broaden the

ammability range.

In the average industrial plant, there would normally be no gases leaking into the surrounding area or, at worst, only a low background level of gas present. Therefore the detecting and early warning system will only be required to detect levels from 0% of gas up to the lower explosive limit. By the time this concentration is reached, shut-down procedures or site clearance should have been put into operation. In fact this will typically take place at a concentration

UEL

(upper explosive limit)

LEL

(lower explosive limit)

0% v/v gas 100% v/v air

of less than 50% of the LEL value, so that an adequate safety margin is provided.

However, it should always be remembered that in enclosed or unventilated areas, a concentration in excess of the UEL can sometimes occur. At times of inspection, special care needs to be taken when operating hatches or doors, since the ingress of air from outside can dilute the gases to a hazardous, combustible mixture.

(N.B LEL/LFL and UEL/UFL are, for the purpose of this publication, interchangeable).

Page 10

Flammable Gas Properties

Ignition Temperature

Flammable gases also have a temperature where ignition

will take place, even without an external ignition source such as a spark or ame. This temperature is called the Ignition Temperature. Apparatus for use in a hazardous area must not have a surface temperature that exceeds the Ignition Temperature. Apparatus is therefore marked with a maximum surface temperature or T rating.

FLASH POINT (F.P. °C)

The ash point of a ammable liquid is the lowest temperature at which the surface of the liquid emits sufcient vapour to be ignited by a small ame. Do not confuse this with Ignition

Temperature as the two can be very different:

Gas / Vapour Flash Point °C Ignition Temp. °C

Methane <-188 595

Kerosene 38 210

Bitumen 270 310

To convert a Celsius temperature into Fahrenheit: Tf = ((9/5)*Tc)+32 E.g. to convert -20 Celsius into Fahrenheit, first multiply the Celsius temperature reading by nine-fifths to get -36. Then add 32 to get -4°F.

VAPOUR DENSITY

Helps determine sensor placement The density of a gas/vapour is compared with air When air = 1.0: Vapour density < 1.0 will rise Vapour density > 1.0 will fall

Gas/Vapour Vapour Density

Methane 0.55

Carbon Monoxide 0.97

Hydrogen Sulphide 1.45

Petrol Vapour 3.0 approx

10 www.honeywellanalytics.com / www.gasmonitors.com

Page 11

GAS

FACT

It’s not just gas that holds

a potential threat - dust

can also be explosive!

Examples of explosive

dusts include polystyrene,

cornstarch and iron.

Page 12

Flammable Gases Data

Molecular

WeightFormulaCAS NumberCommon Name

Acetaldehyde 75-07-0 CH3CHO 44.05 20 1.52 –38 4.00 60.00 74 1,108 204 Acetic acid 64-19-7 CH3COOH 60.05 118 2.07 40 4.00 17.00 100 428 464 Acetic anhydride 108-24-7 (CH3CO)2O 102.09 140 3.52 49 2.00 10.30 85 428 334 Acetone 67-64-1 (CH3)2CO 58.08 56 2.00 <–20 2.50 13.00 80 316 535 Acetonitrile 75-05-8 CH3CN 41.05 82 1.42 2 3.00 16.00 51 275 523 Acetyl chloride 75-36-5 CH3COCl 78.5 51 2.70 –4 5.00 19.00 157 620 390 Acetylene 74-86-2 CH=CH 26 -84 0.90 gas 2.30 100.00 24 1,092 305 Acetyl fluoride 557-99-3 CH3COF 62.04 20 2.14 <–17 5.60 19.90 142 505 434 Acrylaldehyde 107-02-8 CH2=CHCHO 56.06 53 1.93 –18 2.80 31.80 65 728 217 Acrylic acid 79-10-7 CH2=CHCOOH 72.06 139 2.48 56 2.90 85 406 Acrylonitrile 107-13-1 CH2=CHCN 53.1 77 1.83 –5 2.80 28.00 64 620 480 Acryloyl chloride 814-68-6 CH2CHCOCl 90.51 72 3.12 –8 2.68 18.00 220 662 463 Allyl acetate 591-87-7 CH2=CHCH2OOCCH3 100.12 103 3.45 13 1.70 10.10 69 420 348 Allyl alcohol 107-18-6 CH2=CHCH2CH 58.08 96 2.00 21 2.50 18.00 61 438 378 Allyl chloride 107-05-1 CH2=CHCH2Cl 76.52 45 2.64 –32 2.90 11.20 92 357 390 Ammonia 7664-41-7 NH3 17 -33 0.59 gas 15.00 33.60 107 240 630 Aniline 62-53-3 C6H6NH2 93.1 184 3.22 75 1.20 11.00 47 425 630 Benzaldehyde 100-52-7 C6H5CHO 106.12 179 3.66 64 1.40 62 192 Benzene 71-43-2 C6H6 78.1 80 2.70 –11 1.20 8.60 39 280 560 1-Bromobutane 109-65-9 CH3(CH2)2CH2Br 137.02 102 4.72 13 2.50 6.60 143 380 265 Bromoethane 74-96-4 CH3CH2Br 108.97 38 3.75 <–20 6.70 11.30 306 517 511 1,3 Butadiene 106-99-0 CH2=CHCH=CH2 54.09 -4.5 1.87 gas 1.40 16.30 31 365 430 Butane 106-97-8 C4H10 58.1 -1 2.05 gas 1.40 9.30 33 225 372 Isobutane 75-28-5 (CH3)2CHCH3 58.12 -12 2.00 gas 1.30 9.80 31 236 460 Butan-1-ol 71-36-3 CH3(CH2)2CH2OH 74.12 116 2.55 29 1.40 12.00 52 372 359 Butanone 78-93-3 CH3CH2COCH3 72.1 80 2.48 –9 1.50 13.40 45 402 404 But-1-ene 106-98-9 CH2=CHCH2CH3 56.11 -6.3 1.95 gas 1.40 10.00 38 235 440 But-2-ene (isomer not stated) 107-01-7 CH3CH=CHCH3 56.11 1 1.94 gas 1.60 10.00 40 228 325 Butyl acetate 123-86-4 CH3COOCH2(CH2)2CH3 116.2 127 4.01 22 1.20 8.50 58 408 370 n-Butyl acrylate 141-32-2 CH2=CHCOOC4H9 128.17 145 4.41 38 1.20 9.90 63 425 268 Butylamine 109-73-9 CH3(CH2)3NH2 73.14 78 2.52 –12 1.70 9.80 49 286 312 Isobutylamine 78-81-9 (CH3)2CHCH2NH2 73.14 64 2.52 –20 1.47 10.80 44 330 374 Isobutylisobutyrate 97-85-8 (CH3)2CHCOOCH2CH(CH3)2 144.21 145 4.93 34 0.80 47 424 Butylmethacrylate 97-88-1 CH2=C(CH3)COO(CH2)3CH3 142.2 160 4.90 53 1.00 6.80 58 395 289 Tert-butyl methyl ether 1634-04-4 CH3OC(CH3)2 88.15 55 3.03 –27 1.50 8.40 54 310 385 n-Butylpropionate 590-01-2 C2H5COOC4H9 130.18 145 4.48 40 1.00 7.70 53 409 389 Butyraldehyde 123-72-8 CH3CH2CH2CHO 72.1 75 2.48 –16 1.80 12.50 54 378 191 Isobutyraldehyde 78-84-2 (CH3)2CHCHO 72.11 63 2.48 –22 1.60 11.00 47 320 176 Carbon disulphide 75-15-0 CS2 76.1 46 2.64 –30 0.60 60.00 19 1,900 95 Carbon monoxide 630-08-0 CO 28 -191 0.97 gas 10.90 74.00 126 870 805 Carbonyl sulphide 463-58-1 COS 60.08 -50 2.07 gas 6.50 28.50 100 700 209 Chlorobenzene 108-90-7 C6H5Cl 112.6 132 3.88 28 1.30 11.00 60 520 637 1-Chlorobutane 109-69-3 CH3(CH2)2CH2Cl 92.57 78 3.20 –12 1.80 10.00 69 386 250 2-Chlorobutane 78-86-4 CH3CHClC2H5 92.57 68 3.19 <–18 2.00 8.80 77 339 368 1-Chloro-2,3-epoxypropane 106-89-8 OCH2CHCH2Cl 92.52 115 3.30 28 2.30 34.40 86 1,325 385 Chloroethane 75-00-3 CH3CH2Cl 64.5 12 2.22 gas 3.60 15.40 95 413 510 2-Chloroethanol 107-07-3 CH2ClCH2OH 80.51 129 2.78 55 4.90 16.00 160 540 425 Chloroethylene 75-01-4 CH2=CHCl 62.3 -15 2.15 gas 3.60 33.00 94 610 415 Chloromethane 74-87-3 CH3Cl 50.5 -24 1.78 gas 7.60 19.00 160 410 625 1-Chloro-2-methylpropane 513-36-0 (CH3)2CHCH2Cl 92.57 68 3.19 <–14 2.00 8.80 75 340 416 3-Chloro-2-methylprop-1-ene 563-47-3 CH2=C(CH3)CH2Cl 90.55 71 3.12 –16 2.10 77 478 5-Chloropentan-2-one 5891-21-4 CH3CO(CH2)3Cl 120.58 71 4.16 61 2.00 98 440 1-Chloropropane 540-54-5 CH3CH2CH2Cl 78.54 37 2.70 –32 2.40 11.10 78 365 520 2-Chloropropane 75-29-6 (CH3)2CHCl 78.54 47 2.70 <–20 2.80 10.70 92 350 590 Chlorotrifluoroethyl-ene 79-38-9 CF2=CFCl 116.47 -28.4 4.01 gas 4.60 84.30 220 3,117 607

-Chlorotoluene 100-44-7 C6H5CH2Cl 126.58 4.36 60 1.10 55 585

Boiling

Point °C

Relative

Vapourisation Density

12 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 13

References: BS EN 60079-20-1 (supersedes 61779) Electrical apparatus for the detection and measurement of flammable gases-Part 1: General requirements and test methods. NIST Chemistry Web Book June 2005 release. Aldrich Handbook of Fine Chemicals and Laboratory Equipment 2003-2004.

Data may change by country and date, always refer to local up-to-date regulations.

Please note: Where “gas” is stated under Flash Point (F.P. C°), the compound is always in a gaseous state and therefore does not have a FP.

Flammable Limits

F.P. °C LFL % v/v UFL % v/v LFL mg/L UFL mg/L I.T. °C

Page 14

Flammable Gases Data (continued)

Molecular

WeightFormulaCAS NumberCommon Name

Cresols (mixed isomers) 1319-77-3 CH3C5H4OH 108.14 191 3.73 81 1.10 50 555 Crotonaldehyde 123-73-9 CH3CH=CHCHO 70.09 102 2.41 13 2.10 16.00 82 470 280 Cumene 98-82-8 C6H5CH(CH3)2 120.19 152 4.13 31 0.80 6.50 40 328 424 Cyclobutane 287-23-0 CH2(CH2)2CH2 56.1 13 1.93 gas 1.80 42 Cycloheptane 291-64-5 CH2(CH2)5CH2 98.19 118.5 3.39 <10 1.10 6.70 44 275 Cyclohexane 110-82-7 CH2(CH2)4CH2 84.2 81 2.90 –18 1.00 8.00 35 290 259 Cyclohexanol 108-93-0 CH2(CH2)4CHOH 100.16 161 3.45 61 1.20 11.10 50 460 300 Cyclohexanone 108-94-1 CH2(CH2)4CO 98.1 156 3.38 43 1.30 8.40 53 386 419 Cyclohexene 110-83-8 CH2(CH2)3CH=CH 82.14 83 2.83 –17 1.10 8.30 37 244 Cyclohexylamine 108-91-8 CH2(CH2)4CHNH2 99.17 134 3.42 32 1.10 9.40 47 372 293 Cyclopentane 287-92-3 CH2(CH2)3CH2 70.13 50 2.40 –37 1.40 41 320 Cyclopentene 142-29-0 CH=CHCH2CH2CH 68.12 44 2.30 <–22 1.48 41 309 Cyclopropane 75-19-4 CH2CH2CH2 42.1 -33 1.45 gas 2.40 10.40 42 183 498 Cyclopropyl methyl ketone 765-43-5 CH3COCHCH2CH2 84.12 114 2.90 15 1.70 58 452 p-Cymene 99-87-6 CH3CH6H4CH(CH3)2 134.22 176 4.62 47 0.70 5.60 39 366 436 Decahydro-naphthalene trans 493-02-7 CH2(CH2)3CHCH(CH2)3CH2 138.25 185 4.76 54 0.70 4.90 40 284 288 Decane (mixed isomers) 124-18-5 C10H22 142.28 173 4.90 46 0.70 5.60 41 332 201 Dibutyl ether 142-96-1 (CH3(CH2)3)2O 130.2 141 4.48 25 0.90 8.50 48 460 198 Dichlorobenzenes (isomer not stated) Dichlorodiethyl-silane 1719-53-5 (C2H5)SiCl2 157.11 128 24 3.40 223 1,1-Dichloroethane 75-34-3 CH3CHCl2 99 57 3.42 –10 5.60 16.00 230 660 440 1,2-Dichloroethane 107-06-2 CH2ClCH2Cl 99 84 3.42 13 6.20 16.00 255 654 438 Dichloroethylene 540-59-0 ClCH=CHCl 96.94 37 3.55 –10 9.70 12.80 391 516 440 1,2-Dichloro-propane 78-87-5 CH3CHClCH2Cl 113 96 3.90 15 3.40 14.50 160 682 557 Dicyclopentadiene 77-73-6 C10H12 132.2 170 4.55 36 0.80 43 455 Diethylamine 109-89-7 (C2H5)2NH 73.14 55 2.53 –23 1.70 10.00 50 306 312 Diethylcarbonate 105-58-8 (CH3CH2O)2CO 118.13 126 4.07 24 1.40 11.70 69 570 450 Diethyl ether 60-29-7 (CH3CH5)2O 74.1 34 2.55 –45 1.70 36.00 60 1,118 160 1,1-Difluoro-ethylene 75-38-7 CH2=CF2 64.03 -83 2.21 gas 3.90 25.10 102 665 380 Diisobutylamine 110-96-3 ((CH3)2CHCH2)2NH 129.24 137 4.45 26 0.80 3.60 42 190 256 Diisobutyl carbinol 108-82-7 ((CH3)2CHCH2)2CHOH 144.25 178 4.97 75 0.70 6.10 42 370 290 Diisopentyl ether 544-01-4 (CH3)2CH(CH2)2O(CH2)2CH(CH3)2 158.28 170 5.45 44 1.27 104 185 Diisopropylamine 108-18-9 ((CH3)2CH)2NH 101.19 84 3.48 –20 1.20 8.50 49 358 285 Diisopropyl ether 108-20-3 ((CH3)2CH)2O 102.17 69 3.52 –28 1.00 21.00 45 900 405 Dimethylamine 124-40-3 (CH3)2NH 45.08 7 1.55 gas 2.80 14.40 53 272 400 Dimethoxymethane 109-87-5 CH2(OCH)3)2 76.09 41 2.60 –21 2.20 19.90 71 630 247 3-(Dimethylamino)propiononitrile 1738-25-6 (CH3)2NHCH2CH2CN 98.15 171 3.38 50 1.57 62 317 Dimethyl ether 115-10-6 (CH3)2O 46.1 -25 1.59 gas 2.70 32.00 51 610 240 N,N-Dimethylformamide 68-12-2 HCON(CH3)2 73.1 152 2.51 58 1.80 16.00 55 500 440 3,4-Dimethyl hexane 583-48-2 CH3CH2CH(CH3)CH(CH3)CH2CH3 114.23 119 3.87 2 0.80 6.50 38 310 305 N,N-Dimethyl hydrazine 57-14-7 (CH3)2NNH2 60.1 62 2.07 –18 2.40 20 60 490 240 1,4-Dioxane 123-91-1 OCH2CH2OCH2CH2 88.1 101 3.03 11 1.40 22.50 51 813 379 1,3-Dioxolane 646-06-0 OCH2CH2OCH2 74.08 74 2.55 –5 2.30 30.50 70 935 245 Dipropylamine 142-84-7 (CH3CH2CH2)2NH 101.19 105 3.48 4 1.20 9.10 50 376 280 Ethane 74-84-0 CH3CH3 30.1 -87 1.04 gas 2.50 15.50 31 194 515 Ethanethiol 75-08-1 CH3CH2SH 62.1 35 2.11 <–20 2.80 18.00 73 466 295 Ethanol 64-17-5 CH3CH2OH 46.1 78 1.59 12 3.10 19.00 59 359 363 2-Ethoxyethanol 110-80-5 CH3CH2OCH2CH2OH 90.12 135 3.10 40 1.70 15.70 68 593 235 2-Ethoxyethyl acetate 111-15-9 CH3COOCH2CH2OCH2CH3 132.16 156 4.72 47 1.20 12.70 65 642 380 Ethyl acetate 141-78-6 CH3COOCH2CH3 88.1 77 3.04 –4 2.00 2.80 73 470 460 Ethyl acetoacetate 141-97-9 CH3COCH2COOCH2CH3 130.14 181 4.50 65 1.00 9.50 54 519 350 Ethyl acrylate 140-88-5 CH2=CHCOOCH2CH3 100.1 100 3.45 9 1.40 14.00 59 588 350 Ethylamine 75-04-7 C2H5NH2 45.08 16.6 1.50 <–20 3.50 14.00 49 260 425 Ethylbenzene 100-41-4 CH2CH3C6H5 106.2 135 3.66 23 0.80 7.80 44 340 431 Ethyl butyrate 105-54-4 CH3CH2CH2COOC2H5 116.16 120 4.00 21 1.40 66 435 Ethylcyclobutane 4806-61-5 CH3CH2CHCH2CH2CH2 84.16 2.90 <–16 1.20 7.70 42 272 212 Ethylcyclohexane 1678-91-7 CH3CH2CH(CH2)4CH2 112.2 131 3.87 <24 0.80 6.60 42 310 238 Ethylcyclopentane 1640-89-7 CH3CH2CH(CH2)3CH2 98.2 103 3.40 <5 1.05 6.80 42 280 262 Ethylene 74-85-1 CH2=CH2 28.1 -104 0.97 2.30 36.00 26 423 425

106-46-7 C6H4Cl2 147 179 5.07 86 2.20 9.20 134 564 648

Boiling

Point °C

Relative

Vapourisation Density

14 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 15

Flammable Limits

F.P. °C LFL % v/v UFL % v/v LFL mg/L UFL mg/L I.T. °C

Page 16

Flammable Gases Data (continued)

Molecular

WeightFormulaCAS NumberCommon Name

Ethylenediamine 107-15-3 NH2CH2CH2NH2 60.1 118 2.07 34 2.50 18.00 64 396 403 Ethylene oxide 75-21-8 CH2CH2O 44 11 1.52 <–18 2.60 100.00 47 1,848 435 Ethyl formate 109-94-4 HCOOCH2CH3 74.08 52 2.65 –20 2.70 16.50 87 497 440 Ethyl isobutyrate 97-62-1 (CH3)2CHCOOC2H5 116.16 112 4.00 10 1.60 75 438 Ethyl methacrylate 97-63-2 CH2=CCH3COOCH2CH3 114.14 118 3.90 20 1.50 70 Ethyl methyl ether 540-67-0 CH3OCH2CH3 60.1 8 2.10 gas 2.00 10.10 50 255 190 Ethyl nitrite 109-95-5 CH3CH2ONO 75.07 2.60 –35 3.00 50.00 94 1,555 95 Formaldehyde 50-00-0 HCHO 30 -19 1.03 60 7.00 73.00 88 920 424 Formic acid 64-18-6 HCOOH 46.03 101 1.60 42 18.00 57.00 190 1,049 520 2-Furaldehyde 98-01-1 OCH=CHCH=CHCHO 96.08 162 3.30 60 2.10 19.30 85 768 316 Furan 110-00-9 CH=CHCH=CHO 68.07 32 2.30 <–20 2.30 14.30 66 408 390 Furfuryl alcohol 98-00-0 OC(CH2OH)CHCHCH 98.1 170 3.38 61 1.80 16.30 70 670 370 1,2,3-Trimethyl-benzene 526-73-8 CHCHCHC(CH3)C(CH3)C(CH3) 120.19 175 4.15 51 0.80 7.00 470 Heptane (mixed isomers) 142-82-5 C7H16 100.2 98 3.46 –4 0.85 6.70 35 281 215 Hexane (mixed isomers) 110-54-3 CH3(CH2)4CH3 86.2 69 2.97 –21 1.00 8.90 35 319 233 1-Hexanol 111-27-3 C6H13OH 102.17 156 3.50 63 1.10 47 293 Hexan-2-one 591-78-6 CH3CO(CH2)3CH3 100.16 127 3.46 23 1.20 9.40 50 392 533 Hydrogen 1333-74-0 H2 2 -253 0.07 gas 4.00 77.00 3.4 63 560 Hydrogen cyanide 74-90-8 HCN 27 26 0.90 <–20 5.40 46.00 60 520 538 Hydrogen sulphide 7783-06-4 H2S 34.1 -60 1.19 gas 4.00 45.50 57 650 270 4-Hydroxy-4-methyl-penta-2-one 123-42-2 CH3COCH2C(CH3)2OH 116.16 166 4.00 58 1.80 6.90 88 336 680 Kerosene 8008-20-6 150 38 0.70 5.00 210 1,3,5-Trimethylbenzene 108-67-8 CHC(CH3)CHC(CH3)CHC(CH3) 120.19 163 4.15 44 0.80 7.30 40 365 499 Methacryloyl chloride 920-46-7 CH2CCH3COCl 104.53 95 3.60 17 2.50 106 510 Methane (firedamp) 74-82-8 CH4 16 -161 0.55 <–188 4.40 17.00 29 113 537 Methanol 67-56-1 CH3OH 32 65 1.11 11 6.00 36.00 73 665 386 Methanethiol 74-93-1 CH3SH 48.11 6 1.60 4.10 4.10 21.00 80 420 2-Methoxyethanol 109-86-4 CH3OCH2CH2OH 76.1 124 2.63 39 1.80 20.60 76 650 285 Methyl acetate 79-20-9 CH3COOCH3 74.1 57 2.56 –10 3.10 16.00 95 475 502 Methyl acetoacetate 105-45-3 CH3COOCH2COCH3 116.12 169 4.00 62 1.30 14.20 62 685 280 Methyl acrylate 96-33-3 CH2=CHCOOCH3 86.1 80 3.00 –3 1.95 16.30 71 581 415 Methylamine 74-89-5 CH3NH2 31.1 -6 1.00 gas 4.20 20.70 55 270 430 2-Methylbutane 78-78-4 (CH3)2CHCH2CH3 72.15 30 2.50 –56 1.30 8.30 38 242 420 2-Methylbutan-2-ol 75-85-4 CH3CH2C(OH)(CH3)2 88.15 102 3.03 16 1.40 10.20 50 374 392 3-Methylbutan-1-ol 123-51-3 (CH3)2CH(CH2)2OH 88.15 130 3.03 42 1.30 10.50 47 385 339 2-Methylbut-2-ene 513-35-9 (CH3)2C=CHCH3 70.13 35 2.40 –53 1.30 6.60 37 189 290 Methyl chloro-formate 79-22-1 CH3OOCC 94.5 70 3.30 10 7.50 26 293 1,020 475 Methylcyclohexane 108-87-2 CH3CH(CH2)4CH2 98.2 101 3.38 –4 1.00 6.70 41 275 258 Methylcyclo-pentadienes Methylcyclopentane 96-37-7 CH3CH(CH2)3CH2 84.16 72 2.90 <–10 1.00 8.40 35 296 258 Methylenecyclo-butane 1120-56-5 C(=CH2)CH2CH2CH2 68.12 2.35 <0 1.25 8.60 35 239 352 2-Methyl-1-buten-3-yne 78-80-8 HC=CC(CH3)CH2 66.1 32 2.28 –54 1.40 38 272 Methyl formate 107-31-3 HCOOCH3 60.05 32 2.07 –20 5.00 23.00 125 580 450 2-Methylfuran 534-22-5 OC(CH3)CHCHCH 82.1 63 2.83 <–16 1.40 9.70 47 325 318 Methylisocyanate 624-83-9 CH3NCO 57.05 37 1.98 –7 5.30 26.00 123 605 517 Methyl methacrylate 80-62-6 CH3=CCH3COOCH3 100.12 100 3.45 10 1.70 12.50 71 520 430 4-Methylpentan-2-ol 108-11-2 (CH3)2CHCH2CHOHCH3 102.17 132 3.50 37 1.14 5.50 47 235 334 4-Methylpentan-2-one 108-10-1 (CH3)2CHCH2COCH3 100.16 117 3.45 16 1.20 8.00 50 336 475 2-Methylpent-2-enal 623-36-9 CH3CH2CHC(CH3)COH 98.14 137 3.78 30 1.46 58 206 4-Methylpent-3-en-2-one 141-79-7 (CH3)2(CCHCOCH)3 98.14 129 3.78 24 1.60 7.20 64 289 306 2-Methyl-1-propanol 78-83-1 (CH3)2CHCH2OH 74.12 108 2.55 28 1.40 11.00 43 340 408 2-Methylprop-1-ene 115-11-7 (CH3)2C=CH2 56.11 -6.9 1.93 gas 1.60 10 37 235 483 2-Methylpyridine 109-06-8 NCH(CH3)CHCHCHCH 93.13 128 3.21 27 1.20 45 533 3-Methylpyridine 108-99-6 NCHCH(CH3)CHCHCH 93.13 144 3.21 43 1.40 8.10 53 308 537 4-Methylpyridine 108-89-4 NCHCHCH(CH3)CHCH 93.13 145 3.21 43 1.10 7.80 42 296 534

-Methyl styrene 98-83-9 C6H5C(CH3)=CH2 118.18 165 4.08 40 0.80 11.00 44 330 445 Methyl tert-pentyl ether 994-05-8 (CH3)2C(OCH3)CH2CH3 102.17 85 3.50 <–14 1.50 62 345 2-Methylthiophene 554-14-3 SC(CH3)CHCHCH 98.17 113 3.40 –1 1.30 6.50 52 261 433 Morpholine 110-91-8 OCH2CH2NHCH2CH2 87.12 129 3.00 31 1.40 15.20 65 550 230

(isomer not stated)

26519-91-5 C6H6 80.13 2.76 <–18 1.30 7.60 43 249 432

Boiling

Point °C

Relative

Vapourisation Density

16 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 17

Flammable Limits

F.P. °C LFL % v/v UFL % v/v LFL mg/L UFL mg/L I.T. °C

Page 18

Flammable Gases Data (continued)

Molecular

WeightFormulaCAS NumberCommon Name

Naphtha 35 2.50 <–18 0.90 6.00 290 Naphthalene 91-20-3 C10H8 128.17 218 4.42 77 0.60 5.90 29 317 528 Nitrobenzene 98-95-3 CH3CH2NO2 123.1 211 4.25 88 1.40 40.00 72 2,067 480 Nitroethane 79-24-3 C2H5NO2 75.07 114 2.58 27 3.40 107 410 Nitromethane 75-52-5 CH3NO2 61.04 102.2 2.11 36 7.30 63.00 187 1,613 415 1-Nitropropane 108-03-2 CH3CH2CH2NO2 89.09 131 3.10 36 2.20 82 420 Nonane 111-84-2 CH3(CH2)7CH2 128.3 151 4.43 30 0.70 5.60 37 301 205 Octane 111-65-9 CH3(CH2)3CH3 114.2 126 3.93 13 0.80 6.50 38 311 206 1-Octanol 111-87-5 CH3(CH2)6CH2OH 130.23 196 4.50 81 0.90 7.00 49 385 270 Penta-1,3-diene 504-60-9 CH2=CH-CH=CH-CH3 68.12 42 2.34 <–31 1.20 9.40 35 261 361 Pentanes (mixed isomers) 109-66-0 C5H12 72.2 36 2.48 –40 1.40 7.80 42 261 258 Pentane-2,4-dione 123-54-6 CH3COCH2COCH3 100.1 140 3.50 34 1.70 71 340 Pentan-1-ol 71-41-0 CH3(CH2)3CH2OH 88.15 136 3.03 38 1.06 10.50 36 385 298 Pentan-3-one 96-22-0 (CH3CH2)2CO 86.13 101.5 3.00 12 1.60 58 445 Pentyl acetate 628-63-7 CH3COO-(CH2)4-CH3 130.18 147 4.48 25 1.00 7.10 55 387 360 Petroleum 2.80 <–20 1.20 8.00 560 Phenol 108-95-2 C6H5OH 94.11 182 3.24 75 1.30 9.50 50 370 595 Propane 74-98-6 CH3CH2CH3 44.1 -42 1.56 gas 1.70 10.90 31 200 470 Propan-1-ol 71-23-8 CH3CH2CH2OH 60.1 97 2.07 22 2.10 17.50 52 353 405 Propan-2-ol 67-63-0 (CH3)2CHOH 60.1 83 2.07 12 2.00 12.70 50 320 425 Propene 115-07-1 CH2=CHCH3 42.1 -48 gas 2.00 11.10 35 194 455 Propionic acid 79-09-4 CH3CH2COOH 74.08 141 2.55 52 2.10 12.00 64 370 435 Propionic aldehyde 123-38-6 C2H5CHO 58.08 46 2.00 <–26 2.00 47 188 Propyl acetate 109-60-4 CH3COOCH2CH2CH3 102.13 102 3.60 10 1.70 8.00 70 343 430 Isopropyl acetate 108-21-4 CH3COOCH(CH3)2 102.13 85 3.51 4 1.70 8.10 75 340 467 Propylamine 107-10-8 CH3(CH2)2NH2 59.11 48 2.04 –37 2.00 10.40 49 258 318 Isopropylamine 75-31-0 (CH3)2CHNH2 59.11 33 2.03 <–24 2.30 8.60 55 208 340 Isopropyl Chloroacetate 105-48-6 ClCH2COOCH(CH3)2 136.58 149 4.71 42 1.60 89 426 2-Isopropyl-5-methylhex-2-enal 35158-25-9 (CH3)2CH-C(CHO)CHCH2CH(CH3)2 154.25 189 5.31 41 3.05 192 188 Isopropyl nitrate 1712-64-7 (CH3)2CHONO2 105.09 101 11 2.00 100.00 75 3,738 175 Propyne 74-99-7 CH3C=CH 40.06 -23.2 1.38 gas 1.70 16.8 28 280 340 Prop-2-yn-1-ol 107-19-7 HC=CCH2OH 56.06 114 1.89 33 2.40 55 346 Pyridine 110-86-1 C5H5N 79.1 115 2.73 17 1.70 12.40 56 398 550 Styrene 100-42-5 C6H5CH=CH2 104.2 145 3.60 30 1.00 8.00 42 350 490 Tetrafluoroethylene 116-14-3 CF2=CF2 100.02 3.40 gas 10.00 59.00 420 2,245 255 2,2,3,3-Tetrafluoropropyl acrylate 7383-71-3 CH2=CHCOOCH2CF2CF2H 186.1 132 6.41 45 2.40 182 357 2,2,3,3

-Tetrafluoropropyl methacrylate Tetrahydrofuran 109-99-9 CH2(CH2)2CH2O 72.1 64 2.49 –20 1.50 12.40 46 370 224 Tetrahydrofurfuryl alcohol 97-99-4 OCH2CH2CH2CHCH2OH 102.13 178 3.52 70 1.50 9.70 64 416 280 Tetrahydrothiophene 110-01-0 CH2(CH2)2CH2S 88.17 119 3.04 13 1.00 12.30 42 450 200 N,N,N’, N’-Tetramethyldiaminomethane Thiophene 110-02-1 CH=CHCH=CHS 84.14 84 2.90 –9 1.50 12.50 50 420 395 Toluene 108-88-3 C6H5CH3 92.1 111 3.20 4 1.10 7.80 39 300 535 Triethylamine 121-44-8 (CH3CH2)3N 101.2 89 3.50 –7 1.20 8.00 51 339 1,1,1-Trifluoroethane 420-46-2 CF3CH3 84.04 2.90 6.80 17.60 234 605 714 2,2,2-Trifluoroethanol 75-89-8 CF3CH2OH 100.04 77 3.45 30 8.40 28.80 350 1,195 463 Trifluoroethylene 359-11-5 CF2=CFH 82.02 2.83 27.00 502 904 319 3,3,3-Trifluoro-prop-1-ene 677-21-4 CF3CH=CH2 96.05 -16 3.31 4.70 184 490 Trimethylamine 75-50-3 (CH3)3N 59.1 3 2.04 gas 2.00 12.00 50 297 190 2,2,4-Trimethylpentane 540-84-1 (CH3)2CHCH2C(CH3)3 114.23 98 3.90 –12 0.70 6.00 34 284 411 2,4,6-Trimethyl-1,3,5-trioxane 123-63-7 OCH(CH3)OCH(CH3)OCH(CH3) 132.16 123 4.56 27 1.30 72 235 1,3,5-Trioxane 110-88-3 OCH2OCH2OCH2 90.1 115 3.11 45 3.20 29.00 121 1,096 410 Turpentine C10H16 149 35 0.80 254 Isovaleraldehyde 590-86-3 (CH3)2CHCH2CHO 86.13 90 2.97 –12 1.30 13.00 60 207 Vinyl acetate 108-05-4 CH3COOCH=CH2 86.09 72 3.00 –8 2.60 13.40 93 478 425 Vinylcyclohexenes (isomer not stated) Vinylidene chloride 75-35-4 CH2=CCl2 96.94 30 3.40 –18 6.50 16.00 260 645 440 2-Vinylpyridine 100-69-6 NC(CH2=CH)CHCHCHCH 105.14 79 3.62 35 1.20 51 482 4-Vinylpyridine 100-43-6 NCHCHC(CH2=CH)CHCH 105.14 62 3.62 43 1.10 47 501 Xylenes 1330-20-7 C6H4(CH3)2 106.2 144 3.66 30 1.00 7.60 44 335 464

45102-52-1 CH2=C(CH2)COOCH2CF2CF2H 200.13 124 6.90 46 1.90 155 389

51-80-9 (CH3)2NCH2N(CH3)2 102.18 85 3.50 <–13 1.61 67 180

100-40-3 CH2CHC6H9 108.18 126 3.72 15 0.80 35 257

Boiling

Point °C

Relative

Vapourisation Density

18 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 19

Flammable Limits

F.P. °C LFL % v/v UFL % v/v LFL mg/L UFL mg/L I.T. °C

Page 20

Toxic Gas

Hazards

Some gases are poisonous and can be dangerous to life at very low

concentrations. Some toxic gases have strong smells like the distinctive

‘rotten eggs’ smell of Hydrogen Sulphide (H

often used for the concentration of toxic gases are parts per million (ppm) and parts per billion (ppb). For example 1ppm would be equivalent to a room lled with a total of 1 million balls and 1 of those balls being red. The red ball would represent 1ppm.

S). The measurements most

1 MILLION BALLS

ore people die from toxic gas exposure than from explosions caused by the ignition of

noted that there is a large group of gases which are both combustible and toxic, so that even detectors of toxic gases sometimes have to carry hazardous

area approval). The main reason for

ammable gas. (It should be

treating ammable and toxic gases separately

is that the hazards and regulations involved and the types of sensor required are different.

With toxic substances, apart from the obvious environmental problems, the main concern

is the effect on workers of exposure to even very low concentrations, which could be inhaled, ingested, or absorbed through the skin. Since adverse effects can often result from additive, long-term exposure, it is important not only to measure the concentration of gas, but also the total time of exposure. There are even some known cases of synergism,

where substances

can interact and produce a far worse effect when combined than the separate effect of each on its own.

Concern about concentrations of toxic substances in the workplace focus on both organic and inorganic compounds, including the effects they could have on the health and safety of employees, the possible contamination of a manufactured end-product

(or equipment used in its manufacture) and

also the subsequent disruption of normal working activities.

www.honeywellanalytics.com / www.gasmonitors.com20

www.honeywellanalytics.com / www.gasmonitors.com

Page 21

Workplace

Exposure Limits

The term ‘workplace exposure limits’ or ‘occupational

hazard monitoring’ is generally used to cover the area of

industrial health monitoring associated with the exposure

of employees to hazardous conditions of gases, dust,

noise etc. In other words, the aim is to ensure that levels in the workplace are below the statutory limits.

1 RED BALL

100%V/V = 1,000,000ppm 1%V/V = 10,000ppm

EXAMPLE

100%LEL Ammonia = 15%V/V 50%LEL Ammonia = 7.5%V/V 50%LEL Ammonia = 75,000ppm

his subject covers both area

surveys (proling of potential exposures) and personal

worn by a worker and sampling is carried out as near to the breathing zone as possible. This ensures that the measured level of contamination is truly representative of that inhaled by the worker.

It should be emphasised that both personal monitoring and monitoring of the workplace should be considered as important parts of an overall, integrated safety plan. They are only intended to provide the necessary information about conditions as they exist in the atmosphere. This then allows the necessary

monitoring, where instruments are

action to be taken to comply with

the relevant industrial regulations

and safety requirements.

Whatever method is decided upon, it is important to take into account the nature of the toxicity of any of the gases involved. For instance, any instrument which measures only a time-weighted average, or an instrument which draws a sample for subsequent laboratory analysis, would not protect a worker against a short exposure to a lethal dose of a highly toxic substance. On

the other hand, it may be quite normal to briey

exceed the average, Long-Term Exposure Limit

(LTEL) levels in some areas of a plant, and it

need not be indicated as an alarm situation. Therefore, the optimum instrument system should be capable of monitoring both short and long-term exposure levels as well as instantaneous alarm levels.

Page 22

Toxic Exposure Limits

European Occupational Exposure Limits

Occupational Exposure Limit values (OELs) are set by competent

national authorities or other relevant national institutions as limits for

concentrations of hazardous compounds in workplace air. OELs for

hazardous substances represent an important tool for risk assessment and management and valuable information for occupational safety and

health activities concerning hazardous substances.

ccupational Exposure Limits can apply both to marketed products and to waste and by-products

The limits protect workers against health effects, but do not address safety issues such as explosive risk. As limits frequently change and can vary by country, you should consult your relevant national authorities to ensure that you have the latest information.

Occupational Exposure Limits in the UK function under the Control of Substances

Hazardous to Health Regulations (COSHH).

The COSHH regulations require the employer to ensure that the employee’s exposure to substances hazardous to health is either prevented or if not practically possible, adequately controlled.

from production processes.

concentration varies from substance to substance according to its toxicity. The exposure times are averaged for eight hours

(8-hour Time-Weighted Average TWA) and 15 minutes (Short-Term Exposure Limit STEL).

For some substances, a brief exposure is considered so critical that they are set only a STEL, which should not be exceeded even

for a shorter time. The potency to penetrate through skin is annotated in the WEL list by remark “Skin”. Carcinogenicity, reproduction toxicity, irritation and sensitisation potential are considered when preparing a proposal for an OEL according to the present scientic knowledge.

GAS

FACT

Hydrogen is the

lightest, most

abundant and

explosive gas on

Earth.

As of 6 April 2005, the regulations introduced a new, simpler Occupational Exposure Limit system. The existing requirements to follow good practice were brought together by the introduction of eight principles in the Control of Substances Hazardous to Health

(Amendment) Regulations 2004.

Maximum Exposure Limits (MELs) and Occupational Exposure Standards (OESs)

were replaced with a single type of limit -

the Workplace Exposure Limit (WEL). All

the MELs, and most of the OESs, are being transferred into the new system as WELs and will retain their previous numerical values. The OESs for approximately 100 substances were deleted as the substances are now banned, scarcely used or there is evidence to suggest adverse health effects close to the old limit value. The list of exposure limits is known as EH40 and is available from the UK Health and Safety Executive. All legally enforceable WELs in the UK are air limit values. The maximum admissible or accepted

www.honeywellanalytics.com / www.gasmonitors.com22

Page 23

2500

2000

1500

Effects of exposure to Carbon Monoxide

1000

500

Carbon Monoxide in parts per million (ppm)

5 10 20 40 80 160

Period of exposure in minutes

= Noticeable symtoms / start to feel unwell

= Feeling ill

= Death

Page 24

US Occupational Exposure Limits

he Occupational Safety systems in the United States vary from state to state. Here, information is

Occupational Exposure Limits in the USA ACGIH, OSHA, and NIOSH.

The American Conference of Governmental

Industrial Hygienists (ACGIH) publishes Maximum Allowable Concentrations (MAC),

which were later renamed to “Threshold Limit

Values” (TLVs).

Threshold Limit Values are dened as an

exposure limit “to which it is believed nearly all workers can be exposed day after day for a working lifetime without ill effect”. The ACGIH is a professional organisation of occupational hygienists from universities or governmental institutions. Occupational hygienists from private industry can join as associate members. Once a year, the different committees propose new threshold limits or best working practice guides. The list of TLVs includes more than 700 chemical substances and physical agents, as well as dozens of Biological Exposure Indices for selected chemicals.

given on 3 major providers of the

The ACGIH denes different TLV-Types as:

Threshold Limit Value – Time-Weighted Average (TLV-TWA): the Time-Weighted

Average concentration for a conventional 8-hour workday and a 40-hour workweek, to which it is believed that nearly all workers may be repeatedly exposed, day after day, without adverse effect.

Threshold Limit Value – Short-Term Exposure Limit (TLV-STEL): the

concentration to which it is believed that workers can be exposed continuously for a short period of time without suffering from irritation, chronic or irreversible tissue

damage, or narcosis. STEL is dened as a

15-minute TWA exposure, which should not be exceeded at any time during a workday.

Threshold Limit Value – Ceiling (TLV-C): the concentration that should not be exceeded during any part of the working exposure.

There is a general excursion limit recommendation that applies to those TLV-TWAs that do not have STELs. Excursions in worker exposure levels may

Occupational Exposure Limits Comparison Table

ACGIM OSHA NIOSH EH40 Meaning

Threshold Limit

Values (TLVs)

Permissible Exposure

Limits (PELs)

TLV-TWA TWA TWA TWA Long-term Exposure Limit

TLV-STEL STEL STEL STEL Short-Term Exposure Limit

TLV-C Ceiling Ceiling - The concentration that should

Excursion Limit Excursion Limit - - Limit if no STEL stated

- BEIs BEIs - Biological Exposure Indicies

24 www.honeywellanalytics.com / www.gasmonitors.com

Recommended

Exposure Levels (RELs)

Workplace Exposure

Limits (WELs)

Limit definition

(8hr-TWA reference period)

(15-minute exposure period)

not be exceeded during any part of the working exposure

Page 25

exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a workday and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded.

ACGIH-TLVs do not have a legal force in the USA, they are only recommendations. OSHA denes regulatory limits. However, ACGIH-TLVs and the criteria documents are a very common base for setting TLVs in the USA and in many other countries. ACGIH exposure limits are in many cases more protective than OSHA’s. Many US companies use the current ACGIH levels or other internal and more protective limits.

The Occupational Safety and Health

Administration (OSHA) of the US Department

of Labor publishes Permissible Exposure

Limits (PEL). PELs are regulatory limits on

the amount or concentration of a substance

in the air and they are enforceable. The initial set of limits from 1971 was based on the ACGIH TLVs. OSHA currently has around 500 PELs for various forms of approximately 300 chemical substances, many of which are widely used in industrial settings. Existing PELs are contained in a document called “29 CFR 1910.1000”, the air contaminants standard. OSHA uses in a similar way as the ACGIH the following types of OELs: TWAs, Action Levels, Ceiling Limits, STELs, Excursion Limits and in some cases Biological

Exposure Indices (BEIs).

The National Institute for Occupational

Safety and Health (NIOSH) has the statutory

responsibility for recommending exposure levels that are protective to workers.

NIOSH has identied Recommended Exposure Levels (RELs) for around 700

hazardous substances. These limits have no legal force. NIOSH recommends their

limits via criteria documents to OSHA and other OEL setting institutions. Types of RELs are TWA, STEL, Ceiling and BEIs. The recommendations and the criteria are published in several different document types,

such as Current Intelligent Bulletins (CIB), Alerts,

Special Hazard Reviews, Occupational Hazard Assessments and Technical Guidelines.

Page 26

Toxic Gases Data

The toxic gases listed below can be detected using equipment supplied by Honeywell Gas Detection. Gas data is supplied where known. As product development is ongoing, contact Honeywell Analytics if the gas you require is not listed. Data may change by country and date, always refer to local up-to-date regulations.

Ammonia 7664-41-7 NH3 25 18 35 25 50 35 Arsine 7784-42-1 AsH3 0.05 0.16 0.05 0.2 Boron Trichloride 10294-34-5 BCl3 Boron Trifluoride 7637-07-2 BF3 1 (ceiling) 3 (ceiling) Bromine 7726-95-6 Br2 0.1 0.66 0.2 1.3 0.1 0.7 Carbon Monoxide 630-08-0 CO 30 35 200 232 50 55 Chlorine 7782-50-5 Cl2 0.5 1.5 1 (ceiling) 3 (ceiling) Chlorine Dioxide 10049-04-4 ClO2 0.1 0.28 0.3 0.84 0.1 0.3 1,4 Cyclohexane diisocyanate CHDI Diborane 19287-45-7 B Dichlorosilane (DCS) 4109-96-0 H2Cl2Si Dimethyl Amine (DMA) 124-40-3 C2H7N 2 3.8 6 11 10 18 Dimethyl Hydrazine (UDMH) 57-14-7 C2H8N2 Disilane 1590-87-0 Si2H6 Ethylene Oxide 75-21-8 C2H4O 5 9.2 1.5 Fluorine 7782-41-4 F2 1 1.6 1 1.6 0.1 0.2 Germane 7782-65-2 GeH4 0.2 0.64 0.6 1.9 Hexamethylene Diisocyanate (HDI) 822-06-0 C8H12N2O2 Hydrazine 302-01-2 N2H4 0.02 0.03 0.1 0.13 1 1.3 Hydrogen 1333-74-0 H2 Hydrogen Bromide 10035-10-6 HBr 3 10 3 10 Hydrogen Chloride 7647-01-0 HCl 1 2 5 8 5 (ceiling) 7 (ceiling) Hydrogen Cyanide 74-90-8 HCN 10 11 10 11 Hydrogen Fluoride 7664-39-3 HF 1.8 1.5 3 2.5 2 Hydrogen Iodide 10034-85-2 HI Hydrogen Peroxide 7722-84-1 H2O2 1 1.4 2 2.8 1 1.4 Hydrogen Selenide 7783-07-5 H2Se 0.05 0.2 Hydrogen Sulphide 7783-06-4 H2S 5 7 10 14 2 10 Hydrogenated Methylene Bisphenyl Isocyanate (HMDI) Isocyanatoethyl Methacrylate (IEM) C Isophorone Diisocyanate (IPDI) C12H18N2O2 Methyl Fluoride (R41) 593-53-3 CH3F Methylene Bisphenyl Isocyanate (MDI) 101-68-8 C15H10N2O2 Methylene Bisphenyl Isocyanate -2 (MDI-2) 101-68-8 C15H10N2O2 Methylenedianiline (MDA) 101-77-9 C13H14N2 0.01 0.08 Monomethyl Hydrazine (MMH) 60-34-4 CH6N2 Naphthalene Diisocyanate (NDI) 3173-72-6 C12H6N2O2 Nitric Acid 7697-37-2 HNO3 1 2.6 2 5

CAS Number FormulaCommon Name

2H6 0.1 0.1

7H9NO3

26 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 27

Ref: EH40/2005 Workplace Exposure Limits, OSHA Standard 29 CFR 1910.1000 tables Z-1 and Z-2 and ACGIH Threshold Limit Valves and Biological Exposure Indices Book 2005.

EH40 Workplace Exposure Limit (WEL)

Long-Term Exposure Limit

(8-hour TWA reference period)

ppm mg/m

OSHA Permissible

Exposure Limits (PEL)

Short-Term Exposure Limit

(15-minute reference period)

ppm mg/m

Long-term Exposure Limit

(8-hour TWA reference period)

ppm mg/m

Page 28

Toxic Gases Data (continued)

Nitric Oxide 10102-43-9 NO 25 30 Nitrogen Dioxide 10102-44-0 NO2 5 (ceiling) 9 (ceiling) Nitrogen Trifluoride 7783-54-2 NF3 10 29 n-Butyl Amine (N-BA) 109-73-9 C4H11N 5 (ceiling) 15 (ceiling) Ozone 10028-15-6 O3 0.2 0.4 0.1 0.2 Phosgene 75-44-5 COCl2 0.02 0.08 0.06 0.25 0.1 0.4 Phosphine 7803-51-2 PH3 0.1 0.14 0.2 0.28 0.3 0.4 Propylene Oxide 75-56-9 C3H6O 5 12 100 240 p-Phenylene Diamine (PPD) 106-50-3 C6H8N2 0.1 0.1 p-Phenylene Diisocyanate (PPDI) 104-49-4 C8H4N2O2 Silane 7803-62-5 SiH4 0.5 0.67 1 1.3 Stibine 7803-52-3 SbH3 0.1 0.5 Sulphur Dioxide 7446-09-5 SO2 5 13 Sulphuric Acid 7664-93-9 H2SO4 1 Tertiary Butyl Arsine (TBA) Tertiary Butyl Phosphine (TBP) 2501-94-2 C Tetraethyl Orthosilicate (TEOS) 78-10-4 C8H20O4Si Tetrakis (Dimethylamino) Titanium (TDMAT) 3275-24-9 C8H24N4Ti Tetramethyl Xylene Diisocyanate (TMXDI) C14H16N2O2 Toluene Diamine (TDA) 95-80-7 C7H10N2 50 191 150 574 Toluene Diisocyanate (TDI) 584-84-9 C9H6N2O2 0.02 (ceiling) 0.14 (ceiling) Triethyl Amine (TEA) 121-44-8 C6H15N 2 8 4 17 2.5 100 Trimethylhexamethylene Diisocyanate (TMDI) C11H18N2O2 Unsymmetrical Dimethylhydrazine (UDMH) 57-14-7 C2H8N2

CAS Number FormulaCommon Name

4H11P

28 www.honeywellanalytics.com / www.gasmonitors.com

www.honeywellanalytics.com / www.gasmonitors.com

Page 29

EH40 Workplace Exposure Limit (WEL)

Long-Term Exposure Limit

(8-hour TWA reference period)

Short-Term Exposure Limit

(15-minute reference period)

OSHA Permissible

Exposure Limits (PEL)

Long-term Exposure Limit

(8-hour TWA reference period)

ppm mg/m

Page 30

Asphyxiant

Hazard

(Oxygen Deciency)

We all need to breathe the Oxygen (O2) in air to live.

Air is made up of several different gases including

Oxygen. Normal ambient air contains an Oxygen concentration of 20.9% v/v. When the Oxygen level falls below 19.5% v/v, the air is considered Oxygen-decient. Oxygen concentrations below 16% v/v are considered unsafe for humans.

100%

OXYGEN DEPLETION CAN BE CAUSED BY:

• Displacement

• Combustion

• Oxidation

• Chemical reaction

• Bacterial action

20.9%

v/v normal

v/v O

16%

v/v depletion

v/v O

www.honeywellanalytics.com / www.gasmonitors.com30

v/v fatal

Page 31

Oxygen

GAS

Enrichment

FACT

The atomic weight of

Radon is 222 atomic mass

units making it the heaviest

known gas. It is 220 times

heavier than the lightest

gas, Hydrogen.

It is often forgotten that Oxygen enrichment can also cause a risk. At increased O of materials and gases increases. At levels of 24% items such as clothing can spontaneously combust.

Oxyacetylene welding equipment combines Oxygen and Acetylene gas to produce an extremely high temperature. Other areas where hazards may arise from Oxygen enriched atmospheres include

manufacturing areas for storing rocket propulsion systems, products used for bleaching in the pulp and

paper industry and clean water treatment facilities.

Sensors have to be specially certied for use in O

enriched atmospheres.

levels the ammability

Page 32

Typical Areas that Require Gas Detection

There are many different applications for xed and portable gas detection. Industrial

processes increasingly involve the use and manufacture of highly dangerous substances,

particularly toxic and combustible gases. Inevitably, occasional escapes of gas occur, which create a potential hazard to the plant, its employees and people living nearby. Worldwide incidents involving asphyxiation, explosions and loss of life, are a constant reminder of this problem.

Oil and gas (drilling and production)

The oil and gas industry covers a large number of upstream activities from the on and offshore exploration and production of oil and gas to its transportation and storage. The Hydrocarbon gases involved are a serious explosive risk and toxic gases such as Hydrogen Sulphide are often present.

Typical Applications:

• Exploration drilling rigs

• Production platforms

• Onshore oil and gas terminals

• Facility turnarounds/shutdowns

• LPG storage areas

• Offshore and onshore drilling and service rigs

• Offshore production platforms

• Personal Protective Equipment

(PPE)

Typical Gases:

Flammable: Various

Hydrocarbon gases including Methane Toxic: Hydrogen Sulphide, Carbon Monoxide

Oxygen: Depletion

Refineries and petrochemical facilities

Reneries take crude oil mixes

and convert them into various blends of Hydrocarbons for use in a wide variety of subsequent products.

Typical Applications:

• Flanges and pump seals for Hydrocarbon detection

• Catalytic cracking process monitoring

• Bulk storage areas

• Water drains, run-off gullies and trenches

• Conned space entry

• Loading areas

• Ventilation systems

• Perimeter/fence-line monitoring

• Planned maintenance and

shutdown/plant modication

Typical Gases:

Flammable: Various

Hydrocarbon gases including Ethylene, Kerosene, Propane and Methane Toxic: Hydrogen Sulphide and Sulphur Dioxide Oxygen: Depletion

Chemical plants

Chemical plants manufacture a myriad of products and feedstocks. The nature and diversity of chemicals used and produced on site provide considerable danger to assets and personnel. These plants often use a wide range of both ammable and toxic gases in their manufacturing processes.

Typical Applications:

• Raw material storage

• Process areas

• Laboratories

• Pump rows

• Compressor stations

• Loading/unloading areas

Typical Gases:

Flammable: Various

Hydrocarbons including Petroleum and resins Toxic: Various including Hydrogen Sulphide, Hydrogen Fluoride and Ammonia

Power generation (traditional and renewable)

Traditionally fossil fuels like coal, oil and Natural Gas have been used to generate electricity. Today renewable energy is becoming a key aspect of power generation with wind power and biogas becoming more prevalent forms of power generation.

Typical Applications:

• Around boiler pipework and burners

• In and around turbine packages

• Working near landll gas

pipework

• Surface emissions monitoring

in landlls

• Blade production and welding of steel parts (wind energy

manufacture)

• Conned spaces (in the tower and nacelle)

• Working near landll leachate

pools and perimeter boreholes

Typical Gases:

Flammable: Natural Gas,

Hydrogen Toxic: Carbon Monoxide, Sulphur Oxide, Nitrogen Oxide, Hydrogen Sulphide, VOCs Oxygen: Depletion

www.honeywellanalytics.com / www.gasmonitors.com32

Page 33

We have produced various technical documents regarding applications for gas detection. If you would like to access this information, please visit

www.honeywellanalytics.com for xed gas detection

applications and www.gasmonitors.com for portable gas detection applications.

Water treatment

Water treatment is a large industry comprising of many processes and aspects from the production and distribution of clean water to the collection, treatment and disposal of waste such as sewage.

Typical Applications:

• Purication plant monitoring

• Sewage digesters

• Plant sumps

• Plant intakes and penstocks

• Plant power generation monitoring

• Hydrogen Sulphide scrubbers

Typical Gases:

Flammable: Various

Hydrocarbons including Methane Toxic: Hydrogen Sulphide, Carbon Dioxide, Chlorine, Sulphur Dioxide and Ozone Oxygen: Depletion

Marine

Marine gas hazards are numerous. Liquid gas, fuel, chemicals and other fossil fuels harbour a risk of explosion. There is a danger of suffocation from Oxygen displacement when using Nitrogen or other gases for inerting. Toxic gases like Hydrogen Sulphide also pose considerable risks.

Typical Applications:

• Clearance measurements of tanks and cargo bays

• Ship hold inspections

• Vessel entry/below deck entry

• Conned spaces, e.g. electric

motor room, hold spaces and inter-barrier spaces

• Inerting and purging

• Leak detection

• Airlocks

• Burner platform vent hoods

• Engine room gas supply pipelines

Typical Gases:

Flammable: Various

Hydrocarbons including Liquid Natural Gas and Methane Toxic: Hydrogen Sulphide and Carbon Monoxide Oxygen: Depletion

Military and national security

The World’s militaries require gas detection monitoring and due to their mobility, portable gas detection forms a key part of protection against dangerous gases.

Typical Applications:

• Fuel storage tanks

(including inspection)

• Transportation

(particularly of fuel)

• Vehicle refuelling

• Aircraft tank inspections

• Submarine septic tanks and Hydrogen build-up

• Naval vessels engine room monitoring and septic tanks

• Equipment and vehicle maintenance

Typical Gases:

Flammable: Various blends of

Aviation Kerosene, Diesel and Gasoline Toxic: Carbon Monoxide, Carbon Dioxide, Hydrogen Sulphide and

Volatile Organic Compounds (VOCs)

Oxygen: Depletion

Pulp and paper production

This vast industry includes both mechanical and chemical pulping methods that turn wood into a variety of paper based products. Toxic gas threats are present from bleaching agents, whilst fuels used to drive mechanical pulping

create ammable gas risks.

Typical Applications:

• Digesters (in chemical pulping)

• Chlorine during bleaching

• Fuel monitoring in mechanical pulping

Typical Gases:

Flammable: Methane Toxic: Chlorine, Chlorine Dioxide

and Ozone Oxygen: Depletion

Page 34

Typical Areas that Require Gas Detection (continued)

Printing

Depending on the materials being printed, processes within the printing industry use various solvents, inks and dangerous chemicals, which are often dried in very hot ovens, creating the need for robust gas detection to ensure process safety.

Typical Applications:

• Bulk storage of inks and varnishes

• Dryers and ovens

• Exhaust monitoring

Typical Gases:

Flammable: Various

Hydrocarbons including solvents and Methane

Tunnels and car parks

Exhaust fumes can build-up in car parks and tunnels, creating toxic gas hazards. Gas detection is used to monitor the build up of gases like Carbon Monoxide and Methane and also control the ventilation systems.

Typical Applications:

• Car tunnels

• Underground and enclosed car parks

• Ventilation control

• Access tunnels

Typical Gases:

Flammable: Methane,

Liquid Petroleum Gas and Petrol vapour Toxic: Carbon Monoxide and Nitrogen Dioxide

Semiconductor

Manufacturing semiconductor materials involves the use of toxic

and ammable gas. Phosphine,

Arsenic, Boron Trichloride and Gallium are commonly used as doping agents. Hydrogen is used both as a reactant and a reducing atmosphere carrier gas. Etching and cleaning gases include Ammonia and other

peruoro compounds.

Typical Applications:

• Wafer reactor

• Wafer dryers

• Gas cabinets

• Chemical Vapour Deposition

Typical Gases:

Flammable: Hydrogen, Propane,

Silane and Methane Toxic: Hydrogen Chloride, Arsine, Boron Trichloride, Phosphine, Carbon Monoxide, Hydrogen Fluoride, Ozone, Dichlorosilane, Tetraethyl Orthosilicate,

Hexauorobutadiene 1,3, Octauorocyclopentene,

Germane, Ammonia and Nitrogen Dioxide Oxygen: Depletion

Photovoltaics

With more focus on renewable

energy, the photovoltaic (PV)

industry is experiencing considerable growth. PV applications use semiconductors that exhibit the photovoltaic effect in order to convert solar radiation into direct current electricity, and therefore use a semiconductor manufacturing process.

Typical Applications:

• Wafer reactor

• Wafer dryers

• Gas cabinets

• Chemical Vapour Deposition

Typical Gases:

Flammable: Hydrogen, Propane,

Silane and Methane Toxic: Hydrogen Chloride, Arsine, Boron Trichloride, Phosphine, Carbon Monoxide, Hydrogen Fluoride, Ozone, Dichlorosilane, Tetraethyl Orthosilicate,

Hexauorobutadiene 1,3, Octauorocyclopentene,

Germane, Ammonia and Nitrogen Dioxide Oxygen: Depletion

Confined spaces

These locations provide one of the key application uses for portable gas detectors, owing to their ability for dangerous gases to build up (see Conned spaces on page 60

for detailed information).

Typical Applications:

• Shafts

• Trenches

• Sewers and manholes

• Pits

• Boilers

• Tunnels

• Tanks

• Vessels (including marine

vessel tanks)

• Pipelines

• Containers

Typical Gases:

Flammable: Methane Toxic: Carbon Monoxide and

Hydrogen Sulphide Oxygen: Depletion

Building and construction

Various dangerous chemicals are used during construction work and due to the mobility of operatives in these applications, portable gas detection forms an integral part of on-site Personal

Protective Equipment (PPE)

Typical Applications:

• Trenching and shoring

Typical Gases:

Flammable: Methane Toxic: Carbon Monoxide and

Hydrogen Sulphide Oxygen: Depletion

34 www.honeywellanalytics.com / www.gasmonitors.com

Page 35

Typical Areas that Require Gas Detection (continued)

Ammonia Refrigeration

Many industries use refrigeration as part of their processes – from food and beverage manufacture, gas liquefaction and chemical manufacture to cryogenics and Liquid Natural Gas shipping. It is essential to ensure that Ammonia does not build-up, causing potentially explosive atmospheres.

Typical Applications:

• Ammonia storage areas

• Plant room valves, joints and seals

• Chiller and refrigerator monitoring

• Air conditioning systems

Typical Gases:

Flammable: Ammonia Toxic: Ammonia

Laboratory and medical

Laboratories and medical facilities like hospitals may use

many different ammable and

toxic substances. Very large installations may also feature their own on-site utility supplies and back-up power stations.

Typical Applications:

• Laboratories

• Cryogenics and refrigeration

• Boiler rooms

Typical Gases:

Flammable: Methane and

Hydrogen Toxic: Carbon Monoxide, Chlorine, Ammonia and Ethylene Oxide Oxygen: Depletion/enrichment

Steel Mills

Due to the large number of furnaces and processes that subject metals to extreme heat, Carbon Monoxide detection is essential throughout the plant.

Typical Applications:

• Furnace monitoring

• Oven monitoring

Typical Gases:

Toxic: Carbon Monoxide

Landfill monitoring and Biogas generation

Landlls are designed to promote

and accelerate the decomposition of organic material and may also contain sorting and storage areas

for inorganic material. Landll gas (known as Biogas), is often collected

at these sites so care should be taken when personnel are working close to potential sources.

Typical Applications:

• When working near leachate pools

• When working near perimeter boreholes

• When working near landll gas

pipework

• When monitoring surface emissions

• When working near weighbridges

• When handling waste

Typical Gases:

Flammable: Methane Toxic: Carbon Dioxide,

Hydrogen Sulphide, Benzene and Toulene Oxygen: Depletion

Agriculture and live stock

When it comes to keeping livestock, Methane and Ammonia can build-up to dangerous levels in cattle sheds. Agricultural stores where fertilisers and pesticide stocks are held can also pose additional explosive dangers.

Typical Applications:

• Cattle shed monitoring

• Agricultural fertiliser and chemical stores

Mining

There is an abundance of mineral and fossil fuel reserves being mined globally, leaving personnel at risk from dangerous gas build-ups in the enclosed spaces of mine shafts. This makes portable gas detection an essential component of mining safety.

Typical Applications:

• Excavation

• Continuous monitoring whilst working in shafts

Typical Gases:

Flammable: Methane Toxic: Carbon Monoxide Oxygen: Depletion

Commercial buildings and public facilities

Commercial and public facilities like swimming pools, shopping centres and schools use integrated safety systems, which can include gas detection. Large visitor numbers can increase the risk of Carbon Dioxide build-up and heating systems may also need to be monitored for flammable gas leaks.

Typical Applications:

• Mechanical rooms

• Swimming pools

• Schools

• Heating pipework monitoring

• Indoor air quality monitoring

Typical Gases:

Flammable: Methane Toxic: Carbon Dioxide,

Carbon Monoxide, Chlorine Oxygen: Depletion

Turnarounds, plant shutdowns and planned equipment modifications

No matter what the industry and application, planned shutdowns and maintenance schedules create additional risks on site because they represent deviations from standard processes. Gas detection in the form of portable monitoring solutions should always be used to limit these risks when modifying aspects or processes of the plant.

Page 36

Principles of Detection

Combustible Gas Sensors

Many people have probably seen a ame safety

lamp at some time and know something about its

use as an early form of ‘redamp’ (the gases found in coal mines. Also known as “minedamp”) gas

detector in underground coal mines and sewers. Although originally intended as a source of light, the device could also be used to estimate the level of combustible gases - to an accuracy of about 25-50%, depending on the user’s experience, training, age, colour perception etc.

Modern combustible gas detectors have to be much more accurate, reliable and repeatable than this and although various attempts were made to overcome the safety lamp’s subjectiveness of measurement

(by using a ame temperature sensor for instance),

it has now been almost entirely superseded by more modern, electronic devices.

Nevertheless, today’s most commonly used device, the catalytic detector, is in some respects a modern

development of the early ame safety lamp, since it

also relies for its operation on the combustion of a gas and its conversion to Carbon Dioxide and water.

Controller

Signal

Detector

Signal

Sensitive

bead

Catalytic sensor

Nearly all modern, low-cost, combustible gas detection sensors are of the electro-catalytic type. They consist of a very small sensing element sometimes called a ‘bead’, a ‘Pellistor’, or a ‘Siegistor’- the last two being registered trade names for commercial devices. They are made of an electrically heated Platinum wire coil, covered

rst with a ceramic base such as Alumina and then with a nal outer coating of Palladium or

Rhodium catalyst dispersed in a substrate of Thoria.

Non-sensitive

bead

3 Wire mV Bridge Circuit

www.honeywellanalytics.com / www.gasmonitors.com36

This type of sensor operates on the principle that when a combustible gas/air mixture passes over the hot catalyst surface, combustion occurs and the heat evolved increases the temperature of the ‘bead’. This in turn alters the resistance of the Platinum coil and can be measured by using the coil as a temperature thermometer in a standard electrical bridge circuit. The resistance change is then directly related to the gas concentration in the surrounding atmosphere and can be displayed on a meter or some similar indicating device.

Page 37

Speed of response

To achieve the necessary requirements of design safety, the catalytic type of sensor has to be mounted in a strong metal housing behind a ame arrestor. This allows the gas/air mixture to diffuse into the housing and on to the hot sensor element, but will

prevent the propagation of any ame to the outside atmosphere. The ame arrestor

slightly reduces the speed of response of the sensor but, in most cases the electrical output will give a reading in a matter of seconds after gas has been detected. However, because the response curve is

considerably attened as it approaches the nal reading, the response time is often specied in terms of the time to reach 90 percent of its nal reading and is therefore

known as the T90 value. T90 values for catalytic sensors are typically between 20 and 30 seconds.

(N.B. In the USA and some other countries, this value is often quoted as the lower T60 reading and care should therefore be taken when comparing the performance of

different sensors).

100

% Response (Indicated)

T60 T90

(TIME)

Sensor output

To ensure temperature stability under varying ambient conditions, the best catalytic sensors use thermally matched beads. They are located in opposing arms of a Wheatstone bridge electrical circuit, where the ‘sensitive’

sensor (usually known as the ‘s’ sensor)

will react to any combustible gases present, whilst a balancing, ‘inactive’

or ‘non-sensitive’ (n-s) sensor will not.

Inactive operation is achieved by

either coating the bead with a lm of

glass or de-activating the catalyst so that it will act only as a compensator for any external temperature or humidity changes.

A further improvement in stable operation can be achieved by the use of poison-resistant sensors. These have better resistance to degradation by substances such as silicones, Sulphur and lead compounds which can rapidly de-activate (or ‘poison’) other types of catalytic sensor.

Page 38

Principles of Detection (continued)

Typical types of gas sensor/transmitter

Sensor screwed to

Junction Box – two-man

Transmitter with intrusive

calibration

Calibration

The most common failure in catalytic sensors is performance degradation caused by exposure to certain poisons. It is therefore essential that any gas monitoring system should not only be calibrated at the time of installation, but also checked regularly and re-calibrated as necessary. Checks must be made using an accurately calibrated standard gas mixture so that the zero and ‘span’ levels can be set correctly on the controller.

Codes of practice such as EN 60079-29-2 outline the legal requirement for calibrating

ammable gas detectors (%LEL) and also

guidance on the calibration of toxic gas detectors (please note: toxic gas detectors will have a legal requirement for calibration in

the future). Typically, checks should initially

be made at weekly intervals but the periods can be extended as operational experience is gained. Where two alarm levels are required, these are normally set at 20-25%LEL for the lower level and 50-55%LEL for the upper level.

Sensor screwed to

Transmitter with non-intrusive

one-man calibration

Remember that where adjustments have

to be made within a ameproof enclosure, the power must rst be disconnected and a

permit obtained to open the enclosure. Today, there are a number of ‘one-man’ calibration systems available which allow the calibration procedures to be carried out at the sensor itself. This considerably reduces the time and cost of maintenance,

particularly where the sensors are in difcult

to get to locations, such as an offshore oil or gas platform. Alternatively, there are now some sensors available which are

one-man calibration

Sensor screwed to

designed to Intrinsically Safe (IS) standards,

and with these it is possible to calibrate the sensors at a convenient place away from the

site (in a maintenance depot for instance).

Because these sensors are IS, they can be freely exchanged with the sensors needing replacement on site, with no need to shut

down the system rst.

Maintenance can therefore be carried out on a ‘hot’ system and is much faster and cheaper than early, conventional systems.

Transmitter with remote

sensor – one-man

non-intrusive calibration

Older (and lower cost) systems require

two people to check and calibrate, one

to expose the sensor to a ow of gas and

the other to check the reading shown on the scale of its control unit. Adjustments are then made at the controller to the zero and span potentiometers until the reading exactly matches that of the gas mixture concentration.

www.honeywellanalytics.com / www.gasmonitors.com38

Page 39

Principles of Detection (continued)

Infrared Gas Detector

Many combustible gases have absorption bands in the infrared region of the electromagnetic spectrum of light and the

principle of Infrared (IR) absorption has been

used as a laboratory analytical tool for many years. Since the 1980s, however, electronic and optical advances have made it possible

to design equipment of sufciently low power

and smaller size to make this technique available for industrial gas detection products as well.

These sensors have a number of important advantages over the catalytic type. They include a very fast speed of response

(typically less than 10 seconds), low maintenance and greatly simplied checking,

using the self-checking facility of modern micro-processor controlled equipment. They can also be designed to be unaffected by any known ‘poisons’, they are fail-to-safety (no fault that develops within the device can

result in a safety critical situation) and they will

operate successfully in inert atmospheres and under a wide range of ambient temperatures, pressure and humidity conditions.

detected, whilst the other is not. The two light sources are pulsed alternatively and guided along a common optical path to

emerge via a ameproof ‘window’ and then

through the sample gas. The beams are

subsequently reected back again by a retro-reector, returning once more

through the sample and into the unit. Here a detector compares the signal strengths of sample and reference beams and, by subtraction, can give a measure of the gas concentration.

This type of detector cannot detect diatomic gas molecules and is therefore unsuitable for the detection of Hydrogen.

GAS

FACT

Autoignition temperature

of a ammable gas is the

temperature at which an

ignition will take place,

even without an external

spark or ame.

The technique operates on the principle of dual wavelength IR absorption, whereby light passes through the sample mixture at two wavelengths, one of which is set at the absorption peak of the gas to be

Page 40

RSR

Principles of Detection (continued)

Open Path Flammable Infrared Gas Detector

Traditionally, the conventional method of detecting gas leaks was by point detection, using a number of individual sensors to cover an area or perimeter. More recently, however, instruments have become available which make use of infrared and laser technology

in the form of a broad beam (or open path)

which can cover a distance of several hundred metres. Early open path designs were typically used to complement point detection, however the latest generation instruments are now often being used as the primary method of detection. Typical applications where they have had considerable success include FPSOs, loading/unloading terminals, pipelines, perimeter monitoring, offshore

platforms and LNG (Liquid Natural Gas)

storage areas.

Early designs use dual wavelength beams,

the rst coinciding with the absorption band

peak of the target gas and a second reference beam which lies nearby in an unabsorbed area.

The instrument continually compares the two signals that are transmitted through the atmosphere, using either the back-scattered

radiation from a retroreector or more

commonly in newer designs by means of a separate transmitter and receiver. Any changes in the ratio of the two signals is measured as gas. However, this design is susceptible to interference from fog as different types of fog can positively or negatively affect the ratio of the signals and thereby falsely indicate an upscale gas reading/alarm or downscale gas reading/fault. The latest generation design

uses a double band pass lter that has

two reference wavelengths (one either side

of the sample) that fully compensates for

interference from all types of fog and rain. Other problems associated with older designs have been overcome by the use of coaxial optical design to eliminate false alarms caused by partial obscuration of the beam.

The use of Xenon ash lamps and solid state

detectors makes the instruments totally immune to interference from sunlight or other

sources of radiation such as are stacks, arc

welding or lightning.

Open path detectors actually measure the total number of gas molecules (i.e. the

quantity of gas) within the beam. This value

is different to the usual concentration of gas given at a single point and is therefore expressed in terms of LEL meters.

Maximum Intensity of Xenon discharge light

Sunlight

Filament lamp

Detector output

Infrared Intensity

Solid state detectors

Older system lead salt detectors

Single reference design – fog interference

Fog type 1

Upscale gas/false alarm

SR SR

Double reference design – fully compensates

Fog type 1

RSR

Fog type 2

Downscale gas/fault

Fog type 2

www.honeywellanalytics.com / www.gasmonitors.com

Page 41

Principles of Detection (continued)

Electrochemical Cell Sensors

as specic electrochemical

sensors can be used to detect the majority of common toxic

Cl2, SO2 etc. in a wide variety of safety applications.

gases, including CO, H2S,

Patented Surecell™ Two Reservoir Design

Housing

Electrochemical sensors are compact, require very little power, exhibit excellent linearity and repeatability and generally have a long life span, typically one to three years. Response times, denoted as T90, i.e. time to reach

90% of the nal response, are typically 30-60

seconds and minimum detection limits range from 0.02 to 50ppm depending upon target gas type.

Commercial designs of electrochemical cells are numerous but share many of the common features described below:

Three active gas diffusion electrodes are immersed in a common electrolyte, frequently a concentrated aqueous acid or salt solution,

for efcient conduction of ions between the

working and counter electrodes.

Depending on the specic cell the target gas

is either oxidised or reduced at the surface of the working electrode. This reaction alters the potential of the working electrode relative to the reference electrode. The primary function of the associated electronic driver circuit connected to the cell is to minimise this potential difference by passing current between the working and counter electrodes, the measured current being proportional to the target gas concentration. Gas enters the cell through an external diffusion barrier that is porous to gas but impermeable to liquid. Many designs incorporate a capillary diffusion barrier to limit the amount of gas contacting the working electrode and thereby maintaining “amperometric” cell operation.

A minimum concentration of Oxygen is required for correct operation of all electrochemical cells, making them unsuitable for certain process monitoring applications. Although the electrolyte contains a certain amount of dissolved Oxygen, enabling

short-term detection (minutes) of the

target gas in an Oxygen-free environment, it is strongly advised that all calibration

Output pins

gas streams incorporate air as the major component or diluent.

Specicity to the target gas is achieved either

by optimisation of the electrochemistry, i.e. choice of catalyst and electrolyte, or by

incorporating lters within the cell which

physically absorb or chemically react with certain interferent gas molecules in order to

increase target gas specicity. It is important that

the appropriate product manual be consulted to understand the effects of potential interferent gases on the cell response.

The necessary inclusion of aqueous electrolytes within electrochemical cells results in a product that is sensitive to environmental conditions of both temperature and humidity. To address this, the patented

Carbon filter

Working electrode

reservoir

First small electrolyte

Counter electrode

Second expansion

reservoir

GAS

FACT

If you smell the rotten egg

aroma of Hydrogen Sulphide

from the decomposition of

organic matter, you are

only smelling 1ppm.

Just 1,000 ppm of H2S

is enough to

kill you.

Surecell™ design incorporates two electrolyte reservoirs that allows for the ‘take-up’ and ‘loss’ of electrolyte that occurs in high temperature/high humidity and low temperature/low humidity environments.

Electrochemical cell sensor life is typically warranted for 2 years, but the actual lifetime frequently exceeds the quoted values. The exceptions to this are Oxygen, Ammonia and Hydrogen Cyanide sensors where components of the cell are necessarily consumed as part of the sensing reaction mechanism.

Page 42

Principles of Detection (continued)

Photodiode

3 LEDs

Sample Exhaust

Gas stain on Chemcassette

Gas sampling head

Light reflected from tape surface

Sample in

Signals to Microcomputer

Photo Ionised Detection (PID)

his type of detection principle is often employed in portable gas detection solutions and is

monitoring of Volatile Organic Compounds

(VOCs) or other gases that need to be

detected in very small quantities, such as Chlorinated Hyrocarbons.

A PID sensor can detect down to parts per

billion (ppb), and this is necessary when

dealing with VOCs which can be highly toxic in very small quantities.

designed to deliver highly sensitive

Chemcassette

hemcassette® is based on the

use of an absorbent strip of lter

paper acting as a dry reaction

a gas collecting and gas analysing media and it can be used in a continuously operating mode. The system is based on classic colorimetry techniques and is capable of

extremely low detection limits for a specic

gas. It can be used very successfully for

substrate. This performs both as

The principle uses high-energy photons,

which are usually in the Ultraviolet (UV) range

to break gas molecules into positively charged ions. When the gas molecules encounter the UV light, the UV light is absorbed, resulting in the ionisation of the molecules. This occurs because the UV light excites the molecules, resulting in the temporary loss of their electrons and the subsequent formation of positively charged ions. This process causes the gas to become electrically charged and the current resulting from the positively charged ions acts as the gas detector’s signal

a wide variety of highly toxic substances, including Di-isocyanates, Phosgene, Chlorine, Fluorine and a number of the hydride gases employed in the manufacture of semiconductors.

Stain intensity is measured with an

electro-optical system which reects light

from the surface of the substrate to a photo cell located at an angle to the light source.

output. This means that the higher the electrical current, the greater the concentration of the gas in the environment because when there is more gas, more positively charged ions are produced.

PID gas detectors are popular due to their

efciency, low-level detection capabilities and

cost-effectiveness (when compared to other detection principles). Please see Portable gas detection on page 52 for more detailed information about PID detection suitability.

Then, as a stain develops, this reected light

is attenuated and the reduction of intensity is sensed by the photo detector in the form of an analogue signal. This signal is, in turn, converted to a digital format and then presented as a gas concentration, using an internally-generated calibration curve and an appropriate software library. Chemcassette® formulations provide a unique detection medium that is not only fast, sensitive and

specic, but it is also the only available

system which leaves physical evidence, i.e. the stain on the cassette tape that a gas leak or release has occurred.

www.honeywellanalytics.com / www.gasmonitors.com42

Detection specicity and sensitivity are

achieved through the use of specially formulated chemical reagents, which react only with the sample gas or gases. As sample gas molecules are drawn through the Chemcassette® with a vacuum pump, they react with the dry chemical reagents and

form a coloured stain specic to that gas only.

The intensity of this stain is proportionate to the concentration of the reactant gas, ie the higher the gas concentration, the darker the stain. By carefully regulating

both the sampling interval and the ow rate

at which the sample is presented to the Chemcassette®, detection levels as low as parts-per-billion, i.e. 10-9 can be readily achieved.

Page 43

Principles of Detection (continued)

Comparison of Gas Detection Techniques

Detection Principle

Works in inert atmosphere

Resistant to poison

Detects Hydrogen

Performance in 100% humidity

Performance in typical pressure conditions

Performs in all temperatures

enriched

Immune to dust/dirt

Immune to sunlight

Performance in O atmosphere

Immune to human interference

Speed of response

Maintenance requirement

Catalytic ECC Point IR Open Path PID Semiconductor Paper Tape

No (requires presence of Oxygen)

Susceptible to poisons like Lead and Sulphur containing compounds, silicones vapours and phosphates

Yes Yes No No No No No

Yes Yes Yes Yes No Yes No

Yes Yes Yes Yes Yes Yes Yes

Yes No (some models

Yes, with adequate weather and dust protection

Yes Yes Yes Yes Yes Yes

Yes No (can alter

No No No No, e.g. poor

<20 secs <30 secs (typical) <6.5 secs <3-5 secs <5 secs <60 secs <10-30 secs

High High Low Low High High High

No (requires presence of Oxygen)

Yes Yes Yes Yes Susceptible to

can be unstable in low and high temperatures)

Yes, with adequate weather and dust protection

readings and response)

Yes Yes Yes No (requires

presence of Oxygen)

poisons like Halide compounds, Silicone vapours, caustic and acid liquids and concentrated vapours

Yes Yes Yes No (some

models can be compromised below

-40°C and above 90°C)

Yes, with adequate weather and dust protection

Yes Yes Yes No (can alter

Yes, with adequate weather and dust protection

alignment

Yes, with adequate weather and dust protection

No No No

Yes, with adequate weather and dust protection

readings and response)

No (requires presence of Oxygen)

Yes

No (some models can be compromised below 10°C and above 40°C)

Yes, with adequate filter and dust protection

No (decays tape)

No (detection of mineral acids is compromised in Oxygen enriched atmospheres)

Page 44

Selecting Gas Detection

There are many gas detection products on the market that might appear to be the

same, but a closer inspection of specication, functionality and features reveals major differences in what products can do and the potential value they can offer. Similarly,

individual applications are also unique in their respective designs, needs and processes

undertaken.

Know your site risks

efore beginning to consider gas detection equipment, a risk assessment needs to be

employing staff has the obligation to conduct risk assessments to identify potential hazards and these can include potential gas, vapour

or Oxygen deciency risks. If gas hazards are identied, gas detection is applicable as a

risk reduction method.

conducted. Any company

Identifying the prime objective

Depending on the processes being undertaken and the gases being detected,

remote or off-site alarm notication plus

event datalogging/reporting may also be required for Health and Safety management records. Another factor impacting on the need for enhanced reporting functions might be regulatory compliance or a condition of insurance.

Knowing the prime objective and motivation

for having gas detection is the rst step in

selecting the best solution.

Ask the right questions

Having identied the primary objective, the

suitable equipment is selected by asking a number of key questions. These fall into three broad categories:

• The gases to be detected and where they may come from

• The location and environmental conditions where detection is to take place

• The ease of use for operators and routine servicing personnel

The answers to these questions will have a direct impact upon the proposed solution and the associated costs to supply and maintain equipment.

The gases to be detected and where they may come from

The gases to be detected should be identied

by the risk assessment, however experienced gas detection equipment manufacturers and their approved distributors are often able to help in this process, based on their experience of similar applications. However, it is important to remember that it is the end-user’s responsibility to identify all potential hazards.

The gas detection vendor uses published

data to identify whether a gas is ammable,

toxic or an asphyxiant and the relative levels at which it could cause a hazard. An ideally suited gas detection solution aims to detect and alarm prior to dangerous levels being reached. The same published data gives information as to whether the gas or vapour is lighter or heavier than air, as this will affect the selection of sensor positioning at the points of detection.

It is also essential to identify the potential source of a gas release as this helps determine the number and location of

detectors required for a xed gas detection

system.

In instances where the source of gas release is not known, portable gas detection equipment, worn by site personnel may offer a better solution.

Some typical gas sources include:

• Natural occurrence, e.g. Methane and Hydrogen Sulphide from the decomposition of waste

• Leakage for a supply pipe or storage tank, e.g. piped Natural Gas supplies

• Emissions from a combustion process, e.g. Carbon Monoxide from an exhaust or

a boiler ue

• Emissions from a production process, e.g. solvents in the printing and coating industry

• Emissions from a manufacturing plant, e.g. Ammonia from a refrigeration plant or Nitrogen from a Nitrogen supply plant

www.honeywellanalytics.com / www.gasmonitors.com

Page 45

Consider the environmental conditions

The performance, accuracy and reliability of any gas detection equipment will be affected by the environmental conditions it is subjected to. Temperature, humidity and pressure levels at the location all have a direct bearing on the type of equipment that should be selected. Additional factors such as potential variations resulting from a production process itself, diurnal/nocturnal

uctuations and seasonal changes may also

affect the type of device which is suitable. It is important to consider whether the equipment will be used inside or externally as this can greatly affect the design of the device. For example, an external location that is exposed to elements such as wind, rain and salt spray, will require equipment which is resistant to the corrosive effects of that environment. Although indoor locations typically require less robust housing, consideration should be made for internal areas which are hosed down on a frequent basis. In locations where water/moisture, dust and dirt are prevalent it’s important to get a device that is protected by water/dirt ingress. Please see Ingress protection of enclosures on page 92 for more detailed information.

Aside from natural environmental conditions such as weather, there may be other materials in the environment that can have a potential affect on the type of equipment that is

chosen. For example, there may be other elements such as Hydrogen Sulphide, which have corrosive properties or other airborne compounds which could have an adverse affect upon the reliable operation of some sensing technologies, e.g. Silicones poisoning catalytic bead sensing technologies.

Another important consideration is a device’s suitability for use in certain hazardous

locations. Hazard areas are classied

according to their perceived likelihood of gases being present. It’s important that a device cannot ignite a gas cloud. With this in mind equipment that is Intrinsically Safe

(Ex ia/Ex ib) or Explosion-Proof (Ex d) has

been created to provide enhanced safety. Please see Area classication on page 86 for more detailed information.

A competent gas detection equipment supplier will have a range of different sensing technologies available that can be applied to a given application. In addition, the environmental conditions start to determine

the best mechanical conguration of the nal

solution.

Product functionality

The next area of consideration relates to additional product functionality. Aspects

like wiring conguration are important, especially when retro-tting into an existing

application. If the apparatus is being

integrated into a separate safety system, certain communication protocols may also be required such as HART or Modbus®. Please see Communication protocols on page 48 for more detailed information.

Consideration will also need to be given regarding the requirement for local displays

on transmitter units and local conguration

of the unit and gas displays may also be a useful addition.

A holistic approach needs to be adopted when looking at the functionality of a device. There are a large number of variations with products and as you would expect, there is often a cost implication with increased functionality. Again, this is where working with a gas detection specialist can help by identifying the additional spec that could be valuable. Things like local displays, local user interfaces, software compatibility, the number of relays and outputs required, remote sensor mounting capabilities, on-board diagnostics, cartridge hot swapping and event logging

abilities provide additional benets to the user

and make one product more applicable than another.

, Lonworks

The ease of use for operators and routine servicing personnel

Routine maintenance is another important consideration. Some gases and vapours can be detected with a number of different sensing technologies, e.g. Hydrocarbon gases with catalytic beads or Non-dispersive Infrared NDIR. Catalytic beads do not provide fail-to-safety operation and therefore can require a high frequency of routine maintenance, however NDIR based solutions tend to have a higher initial purchase price, but may require less routine maintenance. In-house resource to undertake such routine

maintenance needs to be identied and in the

absence of such a resource, budgeting for third party maintenance is an important factor in selecting the right equipment.

Detection equipment downtime during routine sensor replacement can lead to the loss of production. If this is a concern, some solutions can provide a fast, simple and safe method of sensor exchange without needing to down-power the system or the plant.

A good gas detection equipment supplier should be able to offer a range of service packages to help maintain equipment. Please see Gas detection maintenance and ongoing care on page 106 for detailed information on looking after equipment.

Page 46

Maximising time and efciency

“Smart” functionality may mean different things to different people and encompasses

much more than just a device’s features and in-built intelligence. The smartest solutions are those that provide efciency and cost-effectiveness over the whole product life.

evices with rmware are often

seen as being “smarter” than traditional analogue systems

self-diagnose, improve accuracy, and possibly decrease the amount of time spent calibrating or maintaining the device. Today more than ever, businesses are concerned with reducing

costs and maximising efciency and the choice

of a smart solution can result in considerable savings over whole product life.

This does not necessarily mean that a device can only save you money if it features in-built intelligence. Products can only be properly evaluated within the context of their subsequent use and where they will be

because they may be able to

situated; this means that the application itself, environmental factors and additional elements the device could come into contact with, all impact upon whether one device is really a “smart” choice after all. In some cases, non-intelligent devices may be a better choice for an application. This is highlighted by the divide in the global petrochemical industry with different regions adopting different technologies.

Functionality doesn’t necessarily have to be intelligent to make a big impact. The Sensepoint XCD range from Honeywell Analytics features a tri-colour display that clearly indicates the unit’s status at a glance – even from a distance; green for

normal operation, yellow to indicate a fault status and red to indicate an alarm status. Although there are many models on the market that offer tri-colour LCD indicators, the Sensepoint XCD range provides a full colour-illuminated screen that is easily seen from a distance. An example of the cash saving this functionality could actually translate into can be illustrated by the following example: Consider a plant set-up, where a series of devices are monitoring for gas hazards and are feeding back information

to a Programmable Logic Controller (PLC). If

a hazard occurs, the maintenance engineer

must enter the area, and nd the sensor

that has gone into warning/fault. If the plant is large with many points of detection,

46 www.honeywellanalytics.com / www.gasmonitors.com

Page 47

this could take some time. In the case of Sensepoint XCD, the device in warning/fault will be clearly visible by its bright illuminated screen, meaning that the engineer can get straight to the unit and the simplicity of the colour coding means that the device’s status is instantly accessible with a simple glance.

Aspects like Sensepoint XCD’s tri-colour display screen are not necessarily “smart” in their own right, but as the example highlights, the resulting impact they can have in saving time and subsequent costs may well make them a “smarter” choice over a comparable solution. In addition, the device’s display also negates the need for additional expense associated with integrating local status lights, providing a cost saving.

Save time... save money

The most cost-effective systems are those that permit quick and easy use of the device and minimal training. Even a small reduction in the time required on each device – just a few minutes – can quickly translate into big cash savings, as the following hypothetical example highlights: Consider a site that has 100 catalytic bead driven devices; if each unit takes 10 mins to check and re-calibrate using one solution compared with 6 mins per device using another, a saving of 37% on labour costs is achieved just by saving 4 minutes per device.

Products like the Sensepoint XCD range and the XNX Universal Transmitter from Honeywell Analytics provide complete

monitoring solutions for ammable, toxic and

Oxygen gas hazards and they also feature the same interface and calibration methods. This means that operators do not need to be trained to use each variant separately. This is particularly valuable as plants can evolve and processes can change, meaning additional gas detection solutions may be required. Using devices like these mean that training can be minimised and when you consider the training fees, expenses to get personnel to the location where training is situated and also any cost implications resulting from additional personnel cover whilst training of one group is taking place, this can provide notable savings.

Any minimisation of production loss can save money. Consider a site that uses a device like Sensepoint XCD Remote Flammable

Detector (RFD) to monitor for Methane gas in

a potentially explosive environment. The device’s ability to provide useful warnings that indicate the need for maintenance can help to reduce nuisance alarms.

Smart sensor and calibration philosophies

Ease of sensor swapping and calibration can also deliver savings. This can be highlighted by the auto recognition “Plug and Play” sensor capabilities of devices like Apex from Honeywell Analytics, which use smart pre-calibrated sensors. These sensors can

be taken out into the eld and changed over

in just one minute.

This means that the change out of 100 Apex sensors would take just under two hours to complete compared with a standard sensor technology where each device could take up to 20-30 minutes to change out and re-calibrate (equating to 3 ½ days labour

by comparison).

Speculate to accumulate

The saying “you get what you pay for” often rings true, meaning that more intelligent devices and those that deliver enhanced functionality tend to have a higher purchase price. But often this money can be recouped many times over as can be highlighted by the savings that automatic datalogging can

have on a site’s labour cost. A gas and re

controller that can carry out regular automatic datalogging may cost $500 more (for

argument’s sake) than a controller that cannot

offer this functionality. A site that wishes to datalog every hour will need an engineer to undertake this work manually, if an automatic facility is not available. If each datalog check takes 15 mins to complete, this means that in a 16 hour day (many plants operate two

eight hour shifts per day), 4 hours will be

required to make the relevant checks. By the time the device has been used for a year, the purchaser will have saved around 208 hours in labour.

The same can be said of aspects like intelligent communications platforms such as HART®, Modbus® and LonWorks that facilitate enhanced two-way communication between the device and the control system. This type

of functionality has many potential benets

like assisting with planned maintenance activities, allowing operators to schedule

maintenance and improve time efciency as

well as ensure maximum equipment uptime. For sites using a 4-20mA infrastructure, HART® can deliver enhanced communications without the need for additional cabling, and considering that cabling is the single biggest cost for any site, this is highly valuable. Please see Communications protocols on page 48 for more detailed information.

Field time can also be reduced because

devices that have been inhibited so eld

work can be carried out on them, do not need to be manually put back online by a second employee working in a control room; they can be set to automatically go online. This functionality also limits the occurrence of nuisance false alarms that can adversely impact on a plant’s production.

The value of common design

Today’s devices are being built with not only functionality in mind but also a smarter approach to product design; aspects such as common device and spare parts design enable businesses to carry less spares. As an industry average, 2-5% of the total order is required as additional spares stock. Spares stock can also be reduced through the use of common design devices like XNX Universal Transmitter. Typically using XNX Universal Transmitters, the value of the overall system cost attributable to spares stock can be reduced to one-third of that of a conventional system utilising separate transmitter types. This is achieved through the removal of the need to carry different types of spares for the various transmitter types that may be installed.

Another value aspect of devices that use common design and intuitive user interfaces is that they reduce the chance of incorrect set-up or calibration, which can lead to nuisance alarms. Just one nuisance alarm that causes a required process shutdown of 60-90 minutes at a site producing 1,000 barrels of oil per hour, can equate to 1,500 barrels of lost oil production.

A Case by Case approach

Local factors and individual plant set-up will have a large impact on whether one device is more suitable than another in terms of providing a cash saving. It’s important to work with a supplier who can provide multiple

technologies and specication variance,

as this will enable them to give impartial guidance on choosing the right solution that

is truly t-for-purpose, based on your

individual variables.

Page 48

Communications Protocols

Communication is essential in all areas of life – and gas detection is no exception. In fact, the application of communication capabilities to smart eld devices and process monitoring technologies is able to bring valuable dimensions to site safety.

afety control systems are usually organised with a hierarchical system of three core levels

The highest level is represented by the

Human Machine Interface (HMI), which is

often a PC based solution. This allows an operator to interact and monitor the system, using protected passwords allowing for

acknowledgement and/or modication

as needed. The second level down is the

Programmable Logic Controllers (PLCs).

These allow signals from analogue, digital and bus to interface with the HMI. The tertiary level consists of the devices such as

Infrared (IR) gas detectors, toxic sensors, pressure and temperature sensors and ow measurement eld devices.

The type of communication protocol employed by the system to interface between

the PLCs and eld devices will determine

the type of data that can be obtained from a device and the frequency with which that data can be transmitted or received. Many PLCs tend to use a 4-20mA input.

Communications protocol types

The concept of gas detection with communications capabilities is not a new one; in fact, gas detectors have been using protocols like Foundation Fieldbus™, Modbus®, Probus® and Highway Addressable Remote Transducer (HART®) since the 1980s.

Since the inception of communication protocols, many variants have emerged, with Modbus® being the rst to be developed in

1979. Foundation Fieldbus™ was a protocol released in the 1980s and was strongly

adopted in the USA. Probus® soon emerged

as an alternative to Foundation Fieldbus™ and became popular in Europe.

of hardware and software.

™

Today Foundation Fieldbus Modbus®, Probus® and Industrial Ethernet (an ethernet concept that offers enhanced

data checking and stability).

The plethora of options available is brought about by the varying needs of industry when it comes to communication. Some protocols offer peer-to-peer communication (such as Foundation Fieldbus™), meaning that the PLC is always receiving streamed data as well as being able to request information from the device. Others (such as HART®) work on a master-slave principle where data is not being streamed continuously and the PLC (acting

as master) requests the information from the

slave device, which in turn sends data back to the PLC.

HART® actually operates with two master functions; a Primary Master (such as a PLC or Distributed Control System (DCS) and a Secondary Master (such as a HART®-enabled hand-held device); this provides the user with additional value. For example, an operator can go out into

the eld with a HART®-enabled handheld

interrogator or can use a PLC/DCS situated in a control room or another area.

Modbus® RTU has been very popular for the last 20 years. This is due to the speed with which it can transmit data and the fact it features an error check mechanism to ensure the reliability of data being sent and received, and continues to be popular due to Modbus® TCP/IP over Ethernet.

co-exists with

Honeywell Analytics released its own digital system in 1985 called Gas Data Acquisition and

Control System (GDACS),

using a proprietary protocol. It was created to offer

exibility and an enhanced

level of interaction to its users, and its value has stood the test of time. In fact, today Honeywell Analytics still supports customers using this protocol.

Communications protocol value

Communications protocols offer considerable value, helping to improve safety, simplifying maintenance and reducing ongoing costs:

• They can allow the user to access

information from the smart eld device

(such as gas readings, signal level,

raw sensor readings and temperature)

• They can allow a user to change

calibration and device conguration

• They can help to facilitate proactive, scheduled maintenance over reactive maintenance

• They can reduce ongoing costs because proactive maintenance is less costly than reactive

• They can reduce eld engineering costs,

because device communication allows you to “know before you go”, meaning that an engineer can be prepared for work

needing to be undertaken in the eld.

48 www.honeywellanalytics.com / www.gasmonitors.com

Page 49

Trends and the popularity of HART

Communications protocols all work in slightly different ways and for this reason, they offer

varying benets and disadvantages over each

other. Peer-to-peer communication protocols such as Foundation Fieldbus™ require more power because of the extra data being constantly streamed from the device to the PLC, but conversely they offer the additional

benet of allowing constant communication from the eld device to the PLC, which is

essential for many regulated processes.

HART® is becoming an ever-more popular communication protocol owing to the fact that it communicates over a legacy 4-20mA analogue wiring topology; the digital HART® signal is superimposed over the existing 4-20mA signal and permits bidirectional communication, which allows the operator the

exibility to make device modications using

the HART® signal. Infrastructural costs like wiring are one of the most expensive aspects of a plant, so this ability makes HART® highly attractive to many sites. In fact, its growing popularity highlights the large global install base of 4-20mA wiring. Today it is one of the

most widely adopted communications protocols, and is used by approximately 30 million devices Worldwide.

HART® allows a PLC to issue three types of command: a Universal command for data, which all HART® eld devices respond to, a Common practice command, which

many devices will use and a Device specic

command, which is unique to a particular

device. A Device Description (DD) le is

produced by a manufacturer of a HART®-enabled eld device, and it allows the user to interact directly with a device such as Searchpoint Optima Plus from Honeywell Analytics. This allows the user to poll the device for information and any

procedures specic to that device anywhere

in the loop, using a HART®-enabled

hand-held that includes the DD le from

Honeywell Analytics.

The true value of HART® becomes apparent

in the context of a specic product such as

Searchpoint Optima Plus. In essence, there

are two core areas that a site can benet from

HART®; commissioning/set-up and ongoing

maintenance/operational efciencies.

HART® and universal device use: a winning combination

The advent of “one size ts all” devices like

the XNX Universal Transmitter from Honeywell Analytics are very much in-line with market needs; in fact the perfect solution for most end-users is a universal device that can interface with most existing gas sensing technologies on site, providing one simple, long-lasting solution to ever-changing gas

detection needs. This helps to reduce costs and simplify operation considerably.

XNX Universal Transmitter is an extremely

exible solution that can be congured to

accept an input from any of the Honeywell Analytics range of gas sensor technologies (IR Open Path, IR Point, high temperature sensors, electrochemical cell

and mV), providing one single interface solution to all ammable, toxic and gas

monitoring on site. The device also offers a wide variety of output signals including

HART

, Foundation Fieldbus™, Modbus®,

4-20mA and relays, delivering the exibility

to meet the demands of a wide variety of industries and applications including onshore and offshore oil and gas, power stations and chemical and petrochemical plants.

When this value is combined with the

benets facilitated by HART®, the ongoing

cost of gas detection can be reduced further. HART®-enabled, universal-use eld devices like the XNX Universal Transmitter are likely to grow in popularity, thanks to their functionality and cost saving potential.

GAS

FACT

There are 17 gases in total,

which can be found in the

natural atmosphere on Earth.

Only Oxygen and Nitrogen are

found in large concentrations;

20.9476% and 78.084% respectively.

Page 50

Fixed gas

detection from Honeywell

Honeywell Analytics produces a

comprehensive range of ammable, toxic

and Oxygen gas detectors, with options designed to meet the needs of all industries and applications; from low-cost compliance through to high-end solutions that minimise maintenance and maximise equipment uptime.

Honeywell Analytics

Experts in Gas Detection

Fixed Gas Detection

(Flammable and Toxic)

XNX Universal Transmitter

A universal transmitter compatible with all Honeywell Analytics gas sensor technologies

Series 3000 MkII and MkIII

2-wire loop powered toxic and Oxygen gas detectors for use in potentially explosive atmospheres

Sensepoint XCD

Flammable, toxic and Oxygen transmitter and sensor with tri-colour display for viewing status from a distance

Searchline Excel

World renowned open path IR detector with 200m dynamic monitoring range

Apex

High performance ammable

and toxic detector with a choice of communications platforms

Searchpoint Optima Plus

Market leading point IR detector with 100 gases available. Optional HART® over 4-20mA output

Signalpoint Range

Low cost range of ammable,

toxic and Oxygen gas detectors

Sensepoint High Temperature Sensor

Ideal for combustible gases in high temperature areas

Fixed Gas Detection (Toxic)

Vertex M

Cost effective, 8-24 point toxic gas monitoring with physical evidence of a leak

Vertex

Flexible device providing continuous monitoring of up to 72 points

Midas

Sensitive detection using smart sensor cartridges and Power

over Ethernet (PoE)

Chemcassette®

Calibration-free toxic gas detection with physical evidence of a leak

Sensepoint XCD RFD

A ammable gas transmitter

for use with remotely mounted

ammable gas sensors

Sensepoint XCD RTD

A gas transmitter for use with directly or remotely mounted toxic and Oxygen gas sensors

50 www.honeywellanalytics.com / www.gasmonitors.com

Signalpoint Pro

Low cost range of ammable,

toxic and Oxygen gas detectors with integral gas concentration display

Sensepoint Range

Low cost ATEX certied ammable, toxic and Oxygen

gas detectors

Satellite XT

Small and compact toxic gas detection with a wide range of sensors

Sat-Ex

Comprehensive monitoring of corrosive, combustible and toxic gases in potentially explosive atmospheres

Page 51

SPM Single Point Monitor

A fast response device detecting in the ppb range with physical evidence of a leak

ACM 150 FT-IR

Versatile and sensitive detection of up to W40 points with many gases available

CM4

Low cost continuous monitoring of up to four detection points with minimal maintenance requirements

Controllers

System 57

Precision controller accepting

inputs from toxic, ammable, Oxygen, ame, smoke and

heat detectors

Touchpoint 1

Flammable, toxic and Oxygen controller for use with the Sensepoint range of gas detectors

Touchpoint 4

Flammable, toxic and Oxygen controller for use with the Sensepoint range offering 4 points of detection

Unipoint

DIN rail mounted controller

offering exibility at low cost

Page 52

Portable Gas Detectors

Flammable and toxic gas detection instruments are generally available in two different formats: portable, i.e. ‘spot reading’ detectors and ‘xed’, permanently sited monitors.

Which of these types is most appropriate for a particular application will depend on several factors, including how often the area is accessed by personnel, site conditions, whether the hazard is permanent or transitory, how often testing is needed, and last but

not least, the availability of nances.

ortable instruments probably account for nearly half of the total of all modern, electronic

In most countries, legislation also requires

their use by anyone working in conned

spaces such as sewers and underground telephone and electricity ducts. Generally, portable gas detectors are compact, robust, waterproof and lightweight and can be easily carried or attached to clothing.

gas detectors in use today.

GAS

Portable gas detectors are available as single or multi-gas units. Single gas units contain

one sensor for the detection of a specic gas,

whilst multi-gas units usually contain up to six different gas sensors (typically Oxygen,

ammable, Carbon Monoxide and Hydrogen Sulphide).

Products range from simple alarm only disposable units to advanced fully

congurable and serviceable instruments

with features such as datalogging, internal pump sampling, auto calibration routines and connectivity to other units.

Recent portable gas detector design advances include:

• The use of more robust and lightweight materials for construction

• The use of high power microprocessors, enabling enhanced datalogging and self-checking etc

• The employment of modular designs

that allow simplied routine servicing and

maintenance

• Battery advancements providing extended operating time between charges and a smaller battery pack.

FACT

Hydrogen Sulphide bubbling

up from the sea may have

caused a global extinction of

ora and fauna nearly 250 million years ago.

52 www.honeywellanalytics.com / www.gasmonitors.com

Page 53

5353

Page 54

Portable Gas Detectors (continued)

Why are portable gas detectors so important?

Portable gas detectors are classed as a type

of Personal Protective Equipment (PPE),

designed to keep personnel safe from gas hazards and allow mobile testing of locations before they are entered.

These small devices are essential in many areas where gas hazards could occur, because they are the only means of monitoring an operator’s breathing zone continuously, whilst stationary and moving.

KEY

Detection

FIXED

capability of devices

Monitoring likely sources of a leak (joints and seals)

PROCESS AREA

Spurious fissure in pipework causing a leak

Although xed gas detection does provide

personnel protection in its own right, it cannot move with the operator, and this creates the possibility that the operator could enter an area beyond the detection perimeter of the

xed detector.

Many sites employ a mix of both xed and

portable gas detection, but sometimes portable gas detection is used on its own.

This choice may be made for the following reasons:

• The area may not be entered by personnel

very often, making the addition of xed gas

detection cost-prohibitive

• The area may be small or hard to reach,

making the placement of xed gas

detection impractical

• The application requiring detection may not be stationary itself. For example, when a Liquid Natural Gas tanker is ofoading its cargo at the dock, the dock will be stationary, whilst the tanker itself will be moving due to the motion of the sea

PROCESS AREA

PORTABLE

FIXED

As the operator moves towards the migrating gas, the device will alarm and alert them to the spurious leak

FIXED

54 www.honeywellanalytics.com / www.gasmonitors.com

Page 55

Portable Gas Detectors (continued)

Breathing zone

The breathing zone is dened as the 25 cm/10 inch radius of an operator’s mouth

and nose. A portable device can be xed in

various locations within the breathing zone including being fastened to jackets or to breast pockets (but never inside a pocket), or held in place by a harness/hat clip. It’s essential that the device is secure at all times.

Example of portable gas detector positions

Typical gases requiring portable

Defines breathing zone

Hat clip

25 cm/10 Inch radius from this point

detection

There are diverse applications and environments that require portable gas detection monitoring and numerous toxic and

ammable gases may be encountered.

The most commonly detected gases include:

• Carbon Monoxide

• Carbon Dioxide

• Hydrogen Sulphide

• Oxygen depletion

• Flammable gases such as Methane, Liquid Petroleum Gas and Liquid Natural Gas

• Ammonia

• Sulphur Dioxide

• Chlorine

• Chlorine Dioxide

• Nitrous Oxide

• Nitrous Dioxide

• Phosphine

• Hydrogen Cyanide

• Ozone

• Various Volatile Organic Compounds

(VOCs) including Acetone, Benzene,

Toulene and Xylene

Harness

Enhancing safety with portable gas detectors

Changing legislation and regulatory compliance, combined with evolving insurance pre-requisites are making the use of portable gas detectors more prevalent in many industries.

There is a big drive within many sites to “enhance safety” and the integration of a

portable gas detection eet on site is one way

of assisting with this.

Due to the variety of applications and different processes undertaken, many additional gases may also be detected by portable devices. Please see Typical applications for portable gas detectors on page 60 for information on

which gases are likely to be found in specic

applications.

In addition to legislated requirements (where

compliance is mandatory), many sites also choose to implement site-specic rules; for

example bump testing a portable gas detector before it is used by any operative. Please see Maintaining portable gas detection on page 72 for more information on device testing.

Page 56

Portable Gas Detectors (continued)

Portable gas detector types

There are two primary types of portable gas detector:

• Single gas – devices that are designed to detect one gas

• Multi-gas – devices that can detect multiple gases. Variants usually range from 4 gases up to 6 gases and tend to employ various detection principles in one unit

When it comes to ongoing device operation and maintenance, portable detectors fall into two further groups:

• Serviceable – this means that the device is a long-term solution, requiring ongoing maintenance, which the operator can choose to carry out in-house or via a third party service provider

• Disposable – this means that the device is a short-term solution (2 or 3 year) and does not require any maintenance during its operational life. This type of device is often continuously operational

from rst activation until its expiry.

Operational modes of a portable gas detector

Portable detectors can draw air in (known as sampling) or they can allow air to

diffuse into the sensor, depending on the application needs:

• Diffusion: This is the mode that the portable device will be in the majority of the time it is being used for personnel breathing zone monitoring. As an operator enters an area where a concentration of gas is located, the gas will need to reach the sensor and diffuse into it for the detector to “see” the gas

• Sampling: An integrated motorised pump or sample kit, which includes a hand aspirator, can allow a device to draw air towards the sensor. The ability to sample the air - either manually or using a motorised pump - is safety-critical when an area may contain hazards, because it allows an operator to check the air for gases before entering and breathing the air in.

The following picture shows two examples of BW Technologies by Honeywell’s portable solutions – a single gas disposable device and also a multi-gas detector. Products are shown at actual size.

Multi-gas

GasAlertMicroclip XT

IntelliflashTM visual

compliance indicator

Single gas

GasAlertClip Extreme

Usual alarm indicators

Display

Button operation

Sensor

(gas diffuses in here)

GasAlertClip Extreme dimensions

Dimensions

2.8 x 5.0 x 8.1 cm / 1.1 x 2.0 x 3.2 in.

GasAlertMicroclip XT dimensions

Dimensions

11.3 x 6.0 x 2.9 cm / 4.4 x 2.4 x 1.1 in.

Sensors

56 www.honeywellanalytics.com / www.gasmonitors.com

Page 57

Portable Gas Detectors (continued)

Features and functionality

Due to the diversity of applications and the hazards that are contained within them,

the specication for portable gas detectors

varies considerably.

The key functionality/specication aspects a

portable device delivers and its associated value is detailed in the table below:

Aspect Description Value

Display

Device protection (also known as Ingress Protection)

Button operation

Integrated datalogging

Battery performance

Sensor integration types

Motorised sampling pump

Alarms

Visual compliance indicators

The addition of a display allows the operator to see the monitoring results of the detector. Many devices feature a real-time display and this means that the device visually shows gas values to the operator as well as other operational icons.

The Ingress Protection (IP) rating (please see page 92 for more information) and impact resistance of a device indicates its suitability in challenging environments where water, dust, dirt and other materials may be located.

Some devices (including those provided by Honeywell), use large, single button operation designed to provide simplified interaction. Other devices may feature multiple buttons.

An integrated datalogging capability means that any event (such as an alarm), is automatically stored in the device and can be downloaded later and used for reporting purposes by a portable fleet manager. The amount of data that can be logged will vary from device to device.

Battery type, run time and also charge time can vary considerably from device to device.

Some devices allow individual sensors to be added or removed, whilst others use an integrated sensor cartridge.

A motorised pump allows a device to draw air from a potentially hazardous area without having to enter it. Some devices feature integrated motorised pumps, whilst others don’t.

Most devices feature visual, audible and vibrational alarms to alert operators to hazards.

Some devices, like those from BW Technologies by Honeywell, feature special visual indication LEDs that are automatically de-activated when the device is overdue for calibration or bump testing.

Safety can be enhanced because an operator can see a rising gas value before the alarm is sounded. A display can also provide peace of mind to an operator, through the display of “correct operation” icons and aspects like the gases being detected and how many days until the next calibration. When it comes to disposable devices, a display can also advise of how many operational months are left.

A device that is impact resistant and capable of being submerged in water will provide a flexible monitoring solution that can adapt to many application needs on site. In fact, water treatment and offshore applications require this protection. It also helps to ensure the longevity of a device.

Large, single button operation allows an operator to work with the device more easily and also means that he/she does not need to remove gloves to activate the buttons. This can save considerable time over product life.

Integrated automatic datalogging helps to simplify and assist time-effective event reporting. It is also important to remember that many insurers stipulate detailed reporting.

A high performance, quick charge battery can provide the flexibility to cover long shifts or multiple shifts without needing to be re-charged. A shorter charge cycle can also reduce the number of portables required on site and the power consumption required over product life to charge devices.

Both aspects have their merits: the former allows flexibility in terms of being able to update one sensor if needed, but keeping other sensors intact. Conversely, an integrated sensor cartridge provides a quick and simple means of replacement, thus reducing the time and cost of maintenance over product life.

Applications like confined spaces need to be tested before they can be entered. Testing using a device that can switch between diffusion and sample mode can save time over using a manual sample kit, which needs to be fitted to the device. The flow of air is also regulated with a motorised pump.

It’s essential that a device can get attention – even in high noise locations – so the use of multiple alarm types helps to ensure that an alarm event is never missed. Honeywell’s portable gas detectors feature ultra-bright, wide angled alarms that can be seen easily, supported by loud audible and vibrational alarms that are guaranteed to demand attention in any application.

This aspect can improve site safety and assist considerably with fleet management activities because it makes non-compliant devices easier to spot, prompting operators to ensure their device is maintained in accordance with site standards.

Page 58

Portable Gas Detectors (continued)

Accessories

Portable gas detectors come with a wide range of accessories, which fall into the following categories:

Accessories designed to secure portable devices:

It’s essential a portable gas detector is always securely fastened within the breathing zone. Many jobs demand the use of both hands, and there are various options available that allow a unit to be securely fastened comfortably.

• Lanyards/neck straps in various lengths, which allow the operator to wear a portable securely around his/her neck

• Hard hat clip allowing the device to be secured to the side of a hard hat

• Harnesses securing the device to the chest or other area of the body

Accessories designed to protect devices against water, dust and dirt ingress

Many applications requiring gas detection may be dirty, full of airborne particulates, dusts and water. If the unit is not properly protected, these elements can get into the device’s sensor and prevent it being able to detect gas properly, which can be very dangerous. Additional protection can be

provided by lters designed to prevent debris

and water from getting into the unit and compromising its detection capabilities.

• Sensor protection lters (including hydrophobic and particulate)

• Water oatation aids

Accessories designed to facilitate air sampling

Accessories for power and charging

Sites can have varying shift lengths so it’s important to choose the right power solutions that can meet requirements. Sometimes a number of operators may share a device, so there might not always be time to fully charge between shifts. Car charging kits and cradles provide easy charging on the move for operators who travel.

• Various battery options including Alkaline or Lithium batteries

• Rechargeable battery packs

• Vehicle charger adapters

• Cradles and accompanying chargers

Accessories for datalogging

Accessories designed to protect devices

Although many units are deigned to be “concussion proof” an accidental drop can cause damage which could either compromise the unit’s ability to detect gas and alert to a danger or could limit the operational life of the unit and make ongoing

maintenance difcult. Additional protection

can be used when working in challenging locations.

• Concussion proof boot

• Carrying holster

• Vehicle attachment

If a gas hazard could potentially be present in an area that an operator is planning on

entering, the air should be sampled rst,

using a kit or pump that allows the air to be drawn. Entering an area without carrying out this test could result in death; especially when highly toxic gases could be present. Just one breath of 1000ppm of Hydrogen Sulphide is enough to kill.

• Manual hand aspirator

• Probe and ow tubing

• Test cap (allowing only sampled air to be

drawn into the sensor)

• Pump module (a device that ts over the unit’s sensors and allows air to be drawn)

• Honeywell produces integrated sampling kits and conned space entry kits for its full range of portable gas detection products

When datalogging directly to a PC or laptop is required, USB-based readers provide a quick and simple means of downloading data. Multi-media cards also allow additional data to be stored and held on compatible devices.

• USB memory card readers

• Multimedia cards

58 www.honeywellanalytics.com / www.gasmonitors.com

Page 59

Portable Gas Detectors (continued)

Alarms and status indication

Alarm types

A portable gas detector can be congured to

alarm in various conditions, so that it can alert operators to certain hazard states.

The purpose of an alarm is to indicate an impending danger before it becomes safety-critical or dangerous to health. Please see page 21 for detailed information on Workplace Exposure Limits (WELs).

• Short-term exposure limit (STEL)

(15 min duration)

• Long-term exposure limit (LTEL)

(8hr duration)

• Low level alarm: This denes the low alarm set point

• High level alarm: This denes the high alarm set point

Most portable gas detectors feature three alarm types – audible, visual and vibrational – designed to alert the operator to an alarm event, even in high noise areas, or when the portable gas detector is attached somewhere that the visual alarms cannot be seen (such

as xed to a hard hat).

As previously mentioned, a portable unit can be used in two key ways; to monitor the breathing

zone of an operator (diffusion mode) or to

pre-check an area before an operator enters a location that could contain hazardous gases.

Portables are particularly important when operators are working in areas where toxic gases are present that they can be exposed to for limited amounts of time and in limited concentrations. STEL and LTEL alarm types provide this protection and alert the operator when maximum exposure levels are reached.

Value-added visual status indication

The range from BW Technologies by Honeywell also provides an additional value-added visual indicator that can enhance site safety considerably. IntelliFlashTM, provides a clearly visible green LED indicator to show device compliance to site-standards. When a device

is not maintained correctly, the IntelliashTM

indicator will switch off, highlighting device non-compliance to the operator and also the

eet manager.

Page 60

Portable Gas Detectors (continued)

Typical applications for portable gas detectors

Conned spaces

Conned spaces can be found in a myriad

of industries and applications and are one of the most prevalent applications for portable

gas detection. A conned space is dened as

being:

1. A space that has a limited or a restricted means of entry/exit

2. A space that is large enough for an operator to enter and perform certain tasks

3. A space that is not designed for constant worker occupancy

4. A space where ventilation may be poor, allowing gases to build up

There are two types of conned space:

• A normal conned space (no permit required)

• A permit-required conned space

In addition to the criteria dening a standard conned space, a permit-required conned

space will also have one or more of the following attributes:

• Is known to contain (or has contained) a

hazardous atmosphere

• Is known to contain a recognised safety hazard

• Is known to contain material with the potential for engulfment

• The design of the space itself has the potential to trap or asphyxiate the operator entering the space

Conned space types

Conned spaces can be found in a wide

diversity of industries and applications. Common types include:

• Shafts

• Trenches

• Sewers and manholes

• Pits

• Boilers

• Tunnels

• Tanks

• Vessels (including marine vessel tanks)

• Pipelines

• Containers

60 www.honeywellanalytics.com / www.gasmonitors.com

Page 61

Portable Gas Detectors (continued)

Gas hazards in conned spaces

Depending on the application, numerous gases can be found in conned spaces. The atmosphere may contain a mix of

ammable, toxic and Oxygen depletion gas

hazard risks. The typical gases that may be encountered include but are not limited to:

• Oxygen

• Carbon Monoxide

• Hydrogen Sulphide

• Methane

• Ammonia

• Chlorine

• Nitrogen Dioxide

• Sulphur Dioxide

• Hydrogen Cyanide

Due to the dangerous nature of conned

spaces, a two-step portable monitoring procedure needs to be employed. The area

must rst be tested and then continuous

monitoring of the space must take place for the duration that the operator is working inside it.

GasAlertQuattro

GasAlertMax XT II

GasAlertMicro 5

Conned space stratied testing (Step 1)

Before entering the conned space, a portable gas detector combined with conned space

entry accessories such as manual aspirator kits (if an integrated automatic sampling pump is

not available), and a sample hose with probe

should be used. This will allow the operator to

be located outside of the conned space but

be able to draw air from inside it so it can be tested by the portable gas detector.

It’s essential to sample the air at various levels

from oor to ceiling - heavier-than-air gases will

collect in low lying areas whilst lighter-than-air gases will collect at the highest levels.

- Pay special attention to uneven oors or ceilings that could allow high concentrations of gas to form

- Always sample at a distance from the opening; air can intrude into the conned space resulting in false readings and inaccurate Oxygen level data

- Once this full test has been conducted and no hazards have been found, a worker can

enter the conned space

GasAlertMicroClip XT

Impact Pro

Subsequent continuous

monitoring (Step 2)

Even if no dangers are identied whilst performing the stratied testing, it is essential to monitor the conned space continuously

to ensure the atmosphere remains safe. Always remember that the atmosphere can

change quickly in a conned space.

- Use a 4-gas simultaneous portable gas monitoring solution - 5 or 6 gas devices can be used for additional hazard coverage including Photo Ionised Detection (PID) sensors for the detection of low-level Volatile Organic Compounds (VOCs). This makes solutions like GasAlertMicro 5 from BW Technologies by Honeywell and PHD6TM from Honeywell exible solutions

for all conned space types

- Choose a device with a robust crocodile clip/harness so hands are free to undertake the necessary work. Make sure the portable gas detector is always situated within the breathing zone (no more than 25 cm/10 inches from the

mouth/nose)

PHD6

- “Daisy chain” portable units together, allowing one worker to be inside the

conned space, whilst a second is

monitoring the entrant’s data from a safe location on a second unit. This technique is particularly useful in the most potentially

dangerous conned spaces

Monitoring conned space

applications

4-gas portable devices like Impact Pro from Honeywell Analytics and GasAlertQuattro and GasAlertMicroClip XT from BW Technologies by Honeywell can meet

the needs of most conned spaces, but

additional protection (including VOC

monitoring) can be delivered by a 5-gas

device such as GasAlertMicro 5 from BW Technologies by Honeywell or a 6-gas device like PHD6TM from Honeywell.

Page 62

Portable Gas Detectors (continued)

GasAlertQuattro

Impact Pro

Marine

Marine gas hazards are numerous. Liquid gas, fuel, chemicals and other fossil fuels harbor a risk of explosion and there is a danger of suffocation from Oxygen displacement when using Nitrogen or other gases for inerting.

It is also important to be aware of dangers presented by toxic gases such as Carbon Monoxide from exhaust fumes, or Hydrogen Sulphide from the decomposition of organic compounds found in the briny water inside ballast tanks.

Due to the mobility of ships, portable gas detection is used predominantly as it affords

exibility and mobility.

Marine applications requiring portable gas detection

Portable multi-gas monitoring solutions are an essential part of marine-based PPE, providing operator protection in a variety of applications and environments:

• Protection whilst carrying out clearance measurements of tanks and cargo bays

• Pre-entry check and subsequent

monitoring for conned spaces

• Inerting and purging

• Leak detection

• Conned space entry including:

- Cargo compressor room

- Electric motor room

- Cargo-control room (unless classied as gas-safe)

- Enclosed spaces such as hold spaces and inter-barrier spaces (with the exception of hold spaces containing

Type ‘C’ cargo tanks)

• Airlocks

• Burner platform vent hoods and engine room gas supply pipelines

• Hot work jobs

Gas hazards in marine applications

• Flammables (various ammable fuels are shipped via tanker including

Liquid Petroleum Gas and Liquid Natural Gas)

• Carbon Monoxide

• Hydrogen Sulphide

• Oxygen depletion (from inerting via

Nitrogen)

Marine regulations:

The marine industry is highly regulated due to the potential hazards that can be found, and legislation includes guidance on

specic certications that are required so

portable devices can be used within marine applications:

• Within European Union (EU) Member

States portable gas detectors need to be

certied to the Marine Equipment Directive (MED)

• In some ports and countries across the World it is recommended that portable

gas detectors are certied to the American Bureau of Shipping (ABS)

Monitoring marine applications

This makes devices like GasAlertQuattro from BW Technologies by Honeywell and Impact Pro from Honeywell Analytics, which both feature MED and ABS approval, ideal for marine application monitoring.

62 www.honeywellanalytics.com / www.gasmonitors.com

Page 63

Portable Gas Detectors (continued)

Water treatment

Water treatment is a large industry comprising many processes and aspects from the production and distribution of clean water to the collection, treatment and disposal of waste such as sewage.

Aside from the domestic provision and treatment of clean water, industries such as chemical manufacture, steel and food processing may often have their own water treatment plants.

Water treatment applications requiring portable gas detection

• Purication plant monitoring

- Various chemicals including Chlorine, Sulphur Dioxide and Ammonia are used to remove impurities from water. It’s essential to use robust, multi-gas portable detectors during the purication process and also when entering or working in dosing rooms where chemicals like Ammonia may be used to “sweeten” the water. Carbon Dioxide may also be present, because it is used for PH correction to lower water acidity.

• Sewerage digester plant

- The process of decomposition is accelerated in digesters, allowing

ltered sludge to be converted into

a safe form for disposal. Depending on the origin of the waste, digesters will promote either aerobic (in the presence

of Oxygen) or anaerobic (without the presence of Oxygen) decomposition.

Both Methane and Carbon Dioxide are by-products of these decomposition processes, creating the need for portable gas detection when working near digesters.

Gas hazards in water treatment applications

• Chlorine

• Sulphur Dioxide

• Carbon Dioxide

• Ammonia Flammable gases (Liquid Natural Gas and

Liquid Petroleum Gas)

• Nitrogen Dioxide

• Oxygen

Water treatment regulations:

There are a variety of standards (international

and national) governing the monitoring of toxic, ammable and corrosive substances

used in the water industry. For detailed information on the compliance requirements for EU and Non-EU countries, please visit:

http://ec.europa.eu/environment/water/

water-framework/index_en.html and http://osha.europa.eu/en/good_practice/ topics/dangerous_substances/oel/ nomembers.stm/members.stm.

Monitoring water treatment applications

GasAlertQuattro, GasAlertMicroClip XT and GasAlertMicro 5 from BW Technologies by Honeywell and Impact Pro from Honeywell Analytics ideally meet the monitoring requirements of water treatment applications.

• Power plant monitoring

- Water plants tend to feature their own power generation for the purposes of electricity generation and pumping. This creates the need for fuels like diesel and gas, creating the risk of ammable gas hazards from the fuel itself and also the exhaust fumes (where Carbon Dioxide is a by-product

of combustion). A portable solution with %LEL ammable gas

monitoring is essential in this application.

• Waste water plant intake and penstocks

- As waste water enters the treatment

plant, penstocks (a form of gate) halt/allow the ow of water into the

plant. Flammable risks may be encountered because waste water may contain Hydrocarbons from spillages etc, so portable gas detection is often used to perform regular checks of water coming into the plant.

GasAlertQuattro

Impact Pro

GasAlertMicro 5 GasAlertMicroClip XT

Page 64

Portable Gas Detectors (continued)

Military

Most militaries – regardless of the country they are located in – need to use gasoline, gas oil or Kerosene to power their terrain vehicles, ships, submarines, aircraft and helicopters. Military fuel services contain numerous applications that require portable gas detection.

Militaries use dedicated fuel supply departments to manage and dispatch fuel to all army operatives and in reality, the World’s militaries are one of the biggest volume users of these fuels.

Military applications requiring portable gas detection

• Storage tanks

- Storage tank cleaning

- Storage tank inspections (in particular ballasts where Hydrogen Sulphide and

Carbon Monoxide may build up)

• Pumping

• Storage tank lling

• Transportation

• Distribution

• All works linked fuel management

• Conned space entry and inspection

• Aircraft tank inspection

• Submarine (please see below for more

detailed information)

• Ship monitoring (please see bottom right

for more detailed information)

• Maintenance of engines and pumps

In addition to the applications detailed above, particular care and attention should be given to the following marine-based millitary applications:

• Submarine monitoring: In a submarine the air is controlled by a dedicated analyser to ensure that the atmosphere is consistent and dangerous levels of Carbon Monoxide and Carbon Dioxide are not allowed to build up.

Hydrogen Sulphide is a real risk due to the fact that the batteries that power submarines may produce Hydrogen.

Submarines may also feature ammable

gases and other gases like Volatile Organic Compounds (VOCs), so it’s important to monitor for these too. The septic tank onboard a submarine will also pose a risk for Hydrogen Sulphide.

Special considerations whilst undertaking submarine gas monitoring include the avoidance of using Carbon Monoxide sensors because there can be cross-sensitivity issues between Carbon Monoxide and Hydrogen Sulphide.

• Ship Monitoring: Hydrogen Sulphide is a risk near septic tanks and also where

there are conned spaces so its essential

to use a multi-gas portable when working in the vacinity of these locations.

Carbon Monoxide poses a risk in engine rooms, kitchens and can also be found in

64 www.honeywellanalytics.com / www.gasmonitors.com

Page 65

Portable Gas Detectors (continued)

conned spaces. Ballasts can pose a

danger of Oxygen depletion, as can conned spaces. It’s important to remember that Iron may be oxidised by Oxygen in ambient air, creating Iron Oxide (also known as rust). This means that Oxygen detection may also be required because the creation of rust can deplete

Oxygen levels in the air creating deciency risks. Both VOCs and ammable gas risks

are likely in engine rooms, fuel storage locations and also where fuel is being used, replenished or re-located.

Gas hazards in military applications

• Flammable gases (various blends of

Aviation Kerosene, Diesel and Gasoline)

• Carbon Monoxide

• Carbon Dioxide

• Hydrogen Sulphide

• Volatile Organic Compounds

• Oxygen

Monitoring military fuels

Robust multi-gas solutions that offer sensitive detection combined with useability are ideal for military fuel applications.

Historically, many military applications would specify 2, 3 or 4-gas portables (for the

detection of ammables, Oxygen depletion, Hydrogen Sulphide and Carbon Monoxide),

to monitor for fuel supply-related gas risks. In reality, a 5 or a 6-gas device is actually preferable, as it delivers total coverage against all gas hazards that can be found in fuel supply applications.

Devices like GasAlertMicro 5 PID, from BW Technologies by Honeywell, provides a more comprehensive and effective monitoring solution for military fuel supply, with the ability to detect all toxic and exotic gas risks

that may be encountered. A military-specic

version of GasAlertMicro 5 PID is available (including an automatic device test station

and various additional accessories).

GasAlertMicro 5

PHD6

Bespoke carry case

Page 66

Portable Gas Detectors (continued)

Hazardous Material

(HAZMAT) emergency

response

Accidents and releases involving

Hazardous Materials (HAZMAT) can occur in a

variety of locations including industry, on the roads or at sea during the transportation of materials.

Depending on the nature of the release itself, various emergency response teams may be involved in the isolation and clean-up of

hazardous materials, including re brigades.

Many chemicals and compounds are

classied as HAZMAT, due to their associated

risk and potential detrimental effect to organic life and the environment. This makes quick, enhanced-safety HAZMAT response and clean-up essential to minimise the impact of dangerous solids, liquids and gases and portable gas detection forms a key part of the

Personal Protective Equipment (PPE) used

by HAZMAT responders. Response teams can include various authorities, agencies and groups including:

• Fire departments

• Police

• Spill response teams

• Air transport services

HAZMAT applications requiring portable gas detection

It’s important to remember that incidents involving HAZMAT can occur anywhere, but the following examples are likely applications.

• Chemical spillages on highways

• Chemical spillages at sea

• Accidental releases at industrial plants

• Chemical releases into water ways

• Releases affecting commercial buildings or facilities

• Pipeline infrastructure issues resulting in spills

Gas hazards in HAZMAT applications

• Flammable gases including Liquid Natural Gas, Liquid Petroleum Gas, Crude and Methane

• Carbon Monoxide

• Carbon Dioxide

• Hydrogen Sulphide

• Sulphur Dioxide

• Chlorine

• Nitric Oxide

• Nitrogen Dioxide

• Ammonia

• Phosphine

• Hydrogen Cyanide

• Various Volatile Organic Compounds

• Oxygen

Monitoring HAZMAT response applications

Emergency response teams may hold a stock of various devices that can be used during

specic incidents, owing to the large diversity of HAZMAT classied materials. 4, 5 or 6-gas

portable detectors are ideal for emergency

response because of their exibility. Devices like GasAlertQuattro (4-gas portable), GasAlertMicroClip XT (4-gas portable) and GasAlertMicro 5 PID (5-gas portable) from

BW Technologies by Honeywell, Impact Pro

(4-gas portable) from Honeywell Analytics and

PHD6TM (6-gas) from Honeywell are all ideal solutions for HAZMAT response purposes.

66 www.honeywellanalytics.com / www.gasmonitors.com

GasAlertQuattro

GasAlertMicro 5

Page 67

Portable Gas Detectors (continued)

Oil and gas (offshore

and onshore)

Safety-enhanced portable gas detection forms an integral part of mandatory

Personal Protective Equipment (PPE) required

for these challenging environments, owing to the abundance of potentially explosive atmospheres that can build up during crude extraction, transportation and subsequent

renement.

Floating Production Storage and Ofoading (FPSO) and reneries are classied as

“Top Tier” hazard installations and part of the risk reduction requirement includes the use of portable gas detectors.

Offshore applications are often hard to reach and accidents may require air rescue and air emergency response, creating the need for

enhanced safety. Numerous ammable and

toxic gas hazards exist, including Oxygen depletion risks from inerting with Nitrogen. These locations may also be subject to severe adverse weather and sea spray, creating the need for the most robust solutions

with enhanced Ingress Protection (IP).

Oil and gas applications requiring portable gas

Gas hazards in oil and gas applications

detection

• Flammable gases including

A wide variety of applications require portable gas detection, but best practice guidance is that operators should always use a portable device to monitor for Hydrogen Sulphide.

• Conned space testing and entry

• Inerting of storage tanks

• Crude extraction from the sea bed

• When working near storage tank farms

• Loading and ofoading ammable liquid/materials for transportation

• Working near renery processes such as

Hydrocarbon cracking

• During permit to work testing and when working in permit controlled areas

The aforementioned examples represent some of the key applications for portable gas detection but if you are interested to learn about additional applications, please visit:

www.gasmonitors.com for application notes relating to portable products and www.honeywellanalytics.com for application notes relating to xed products.

Liquid Natural Gas, Liquid Petroleum Gas, Crude and Methane

• Carbon Monoxide

• Hydrogen Sulphide

• Carbon Dioxide

• Sulphur Dioxide

• Ammonia

• Nitrogen Dioxide

• Oxygen

Monitoring oil and gas applications

4-gas portable detectors with IP 66/67 like Impact Pro from Honeywell Analytics, GasAlertQuattro and GasAlertMicroClip XT from BW Technologies by Honeywell and MultiProTM from Honeywell provide the ideal monitoring solutions for these applications.

Page 68

Portable Gas Detectors (continued)

PID Information

Measuring Solvent, fuel and VOC vapours in the workplace environment

Solvent, fuel and many other

Volatile Organic Compound (VOCs)

vapours are pervasively common in many

workplace environments. Most have surprisingly low occupational exposure limits. For most VOCs, long before you reach a concentration sufcient to register

on a combustible gas indicator, you will

have easily exceeded the toxic exposure limits for the contaminant.

A wide range of techniques and equipment are available for measuring the concentrations of these contaminants in air. However, PID equipped instruments are generally the best choice for measurement of VOCs at exposure limit concentrations. Whatever type of instrument is used to measure these hazards, it is essential that the equipment is used properly and the results are correctly interpreted.

(VOCs) are organic compounds

characterised by their tendency to evaporate easily at room temperature. Familiar substances containing VOCs include solvents, paint thinner and nail polish remover, as well as the vapours associated with fuels such as gasoline, diesel, heating oil, kerosene and jet fuel. The category also includes many

specic toxic substances such as

Benzene, Butadiene, Hexane, Toluene, Xylene, and many others. Increased awareness of the toxicity of these common contaminants has led to lowered exposure limits and increased requirements for direct measurement of these substances at their exposure limit concentrations. Photoionisation detector equipped instruments are increasingly being used as the detection technique of choice in these applications.

VOCs present multiple potential threats in the workplace environment. Many VOC

vapours are heavier than air, and can act to displace the atmosphere in an enclosed

environment or conned space. Oxygen deciency is a leading cause of injury and death in conned space accidents. The

accident reports contain many examples of fatal accidents caused by Oxygen deciencies due to displacement by VOC vapours.

Most VOC vapours are ammable at

surprisingly low concentrations. For

instance, the Lower Explosive Limit (LEL)

concentrations for Toluene and Hexane are

only 1.1% (11,000 PPM). By comparison,

it takes 5% volume Methane (50,000 PPM)

to achieve an ignitable concentration in air.

Because most VOCs produce ammable

vapours, in the past, the tendency has been to measure them by means of combustible gas measuring instruments. Combustible gas reading instruments usually provide readings in percent LEL increments, where 100% LEL indicates a fully ignitable concentration of gas. Combustible gas instrument alarms are usually set to go off if the concentration exceeds 5% or 10% LEL. Unfortunately, most VOC vapours are also toxic, with Occupational Exposure Limit

(OEL) values much lower than the 5% or

10% LEL hazardous condition threshold for combustible gas. The toxic exposure limits are exceeded long before the LEL alarm concentration is reached.

(OELs) are designed to protect workers

against the health effects of exposure

to hazardous substances. The OEL

is the maximum concentration of an

airborne contaminant to which an

unprotected worker may be exposed

during the course of workplace

activities. In the United Kingdom, OELs are listed in the EH40 Maximum Exposure Limits and Occupational Exposure Standards.

EH40 currently lists exposure limits for about 500 substances. These OELs are enforceable. Unprotected workers may not be exposed to a concentration of any listed substance that exceeds the limit. It’s up to the employer to determine that these exposure limits are not exceeded. In many cases, a direct

reading gas detector is the primary means used to ensure that the OEL has not been exceeded. OELs are

generally dened in two ways, by

means of a Long Term Exposure

Limit (LTEL) calculated as an 8-hour

Time Weighted Average (TWA)

and/or a Short Term Exposure Limit

(STEL) that represents the maximum

allowable concentration over a shorter period of time - usually a 10

or 15 minute period. Exposure limits

for gases and vapours are usually

expressed in parts per million (PPM) or

mg/m3 increments. The TWA concept

68 www.honeywellanalytics.com / www.gasmonitors.com

Page 69

Portable Gas Detectors (continued)

is based on a simple average of worker exposure during an 8-hour day. The TWA concept permits excursions above the TWA limit only as long as they do not exceed the STEL or ceiling and are compensated by equivalent excursions below the limit. For VOC vapours without a STEL, depending on the jurisdiction, the generally suggested approach is to limit excursions above the

TWA to a maximum of two to ve times

the 8-hour TWA OEL, averaged over a 10 to 15 minute period. Most direct reading instruments include at least three separate alarms for each type of toxic gas measured. Typically, a toxic gas instrument will include an 8-hour TWA alarm, a STEL alarm and an instantaneous Ceiling alarm, (sometimes

called the “Peak” alarm), that is activated

immediately whenever this concentration is exceeded. Most gas detector manufacturers set their initial instantaneous “Peak” alarm to the 8-hour TWA limit. This is a very conservative approach. Although it is legally permissible to spend an entire 8-hour day at this concentration, most direct reading VOC instruments are set to go into alarm the moment the instantaneous concentration exceeds the TWA limit. Instrument users, of course, are free to modify factory alarm settings to meet the demands of their

specic monitoring programs. Airborne toxic substances typically are classied on the

basis of their ability to produce physiological

effects on exposed workers. Toxic substances tend to produce symptoms in two time frames: acute and chronic. Hydrogen Sulphide (H2S) is a good example of an acutely toxic substance that is immediately lethal at relatively low concentrations. Exposure to 1,000 PPM produces rapid paralysis of the respiratory system, cardiac arrest, and death within

minutes. Carbon Monoxide (CO) also can act rapidly at high concentrations (1,000 PPM)

although not as rapidly as Hydrogen Sulphide.

While some VOCs are acutely toxic at low concentrations, most are chronically toxic, with symptoms that may not become fully manifested for years. Exposure can be via skin or eye contact with liquid or aerosol droplets, or via inhalation of VOC vapours. Inhalation can cause respiratory tract irritation (acute or

chronic) as well as effects on the nervous

system such as dizziness, headaches and other long-term neurological symptoms. Long-term neurological symptoms can include diminished cognition, memory, reaction time, and hand-eye and foot-eye coordination, as well as balance and gait disturbances. Exposure can also lead to mood disorders, with depression, irritability, and fatigue being common symptoms. Peripheral neurotoxicity effects include

tremors, and diminished ne and gross

motor movements. VOCs have also been implicated in kidney damage and immunological problems, including increased cancer rates. Benzene, a notoriously toxic VOC found in gasoline, diesel, jet fuel and other chemical products, has been linked to chemically induced leukemia, aplastic anaemia and multiple myeloma (a cancer

of the lymphatic system). There is good

reason that the OEL’s for VOC vapours are as low as they are. Unfortunately, because of the chronic or long-term nature of the physiological effects of exposure, the tendency in the past has been to overlook their potential presence in the workplace environment at OEL concentrations.

Real-time measurement techniques for VOC vapours

Commonly used techniques used to measure VOC vapours include colorimetric detector

tubes, passive (diffusion) badge dosimeters,

sorbent tube sampling systems, combustible gas monitors that use catalytic “Hot Bead” combustible gas sensors to detect vapours in percent LEL or PPM ranges, photoionisation

detectors (PIDs), ame ionisation detectors (FIDs) and infrared spectra-photometers.

Page 70

Portable Gas Detectors (continued)

All of these techniques are useful, or even

mandatory in specic monitoring applications.

However, the balance of this article will deal with the most widely used types of portable instruments used for VOC measurement in industrial safety applications: compact multi-sensor instruments equipped with Oxygen, LEL combustible, electrochemical toxic and miniaturised photoionisation

detectors (PIDs). Portable gas detectors can

be equipped with a number of different types of sensors. The type of sensor used is a function of the specic substance or class of contaminant being measured. Many toxic contaminants can be measured by means

of substance-specic electrochemical

sensors. Direct reading sensors are available

for Hydrogen Sulphide, Carbon Monoxide, Chlorine, Sulphide Dioxide, Ammonia, Phosphine, Hydrogen, Hydrogen Cyanide, Nitrogen Dioxide, Nitric Oxide, Chlorine Dioxide, Ethylene Dioxide, Ozone and others.

Although some of these sensors are cross-sensitive to other substances, there is very little ambiguity when it comes to interpreting readings. When you are interested in Hydrogen Sulphide, you use a Hydrogen Sulphide sensor. When you are interested in Phosphine, you use a Phosphine sensor. In many cases, however, a substance-specific sensor may not be available.

VOCs are quite detectable, but usually only by means of broad-range sensors. Broad-range sensors provide an overall reading for a general class or group of chemically related contaminants. They cannot distinguish between the different contaminants they are able to detect. They provide a single aggregate reading for all of the detectable substances present at any moment.

The most widely used technique for the measurement of combustible gases and VOCs continues to be the use of a hot-bead pellistor type combustible gas sensor. Pellistor sensors detect gas by oxidising the gas on an active bead located within the sensor. Oxidisation of the gas causes heating of the active bead. The heating is proportional to the amount of gas present in the atmosphere being monitored, and is used as the basis for the instrument reading. Most combustible gas reading instruments display readings in % LEL increments, with a full range of 0 - 100% LEL. Typically these sensors are used to provide a hazardous condition threshold alarm set to 5% or 10% of the LEL concentration of the gases or vapours being measured. Readings are usually displayed in increments of + 1% LEL.

Hot-bead pellistor combustible gas sensors are unable to differentiate between different combustible gases. Hot-bead pellistor sensors that display readings in + 1% LEL increments are excellent for gases and vapours that are primarily or only of interest

from the standpoint of their ammability.

Many combustible gases, such as Methane, do not have a permissible exposure limit. For these gases using a sensor that expresses readings in percent LEL, increments is an excellent approach. But many other combustible vapours fall into a different category. Although VOC vapours may be measurable by means of a hot-bead sensor, they may also have an OEL that requires taking action at a much lower concentration.

Hexane provides a good example. Most internationally recognised standards, such as the Federal Republic of Germany Maximum

Concentration Value (MAK), the American

Conference of Governmental Hygienists (ACGIH®) Threshold Limit Value (TLV®) and the United States National Institute of

Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

reference an 8-hour TWA for Hexane of 50 PPM. In the United Kingdom, the OEL for

70 www.honeywellanalytics.com / www.gasmonitors.com

Page 71

Portable Gas Detectors (continued)

Hexane is even more conservative. In the EU, the Long Term Exposure Limit (LTEL) for Hexane is a maximum of only 20 PPM calculated as an 8-hour TWA.

The LEL concentration for Hexane is

1.1%. Below 1.1% volume Hexane the concentration of Hexane vapour to air is too low to form an ignitable mixture. Assuming the combustible sensor alarm is set at 10% LEL, with a properly calibrated combustible gas reading instrument, it would take a concentration of 10% of 1.1% =

0.11% volume Hexane to trigger an alarm. Since 1% volume = 10,000 parts-per-million

(PPM), every 1% LEL increment for Hexane

is equivalent to 110 PPM. It would therefore take a concentration of 1,100 PPM Hexane to trigger an alarm set to the standard 10% LEL hazardous condition threshold. Even if instruments are set to alarm at 5% LEL, it would require a concentration of 550 PPM to trigger the alarm.

Using a combustible gas monitor to measure VOCs presents a number of other potential problems. To begin with, most combustible sensors have poor sensitivity to the large molecules found in fuels, solvents and other

VOCs, with ashpoint temperatures higher than 38ºC (100ºF). But even when the span

sensitivity of a properly calibrated instrument

has been increased sufciently to make up

for inherently lower sensitivity, an instrument that provides readings incremented in

1.0% LEL steps cannot resolve changes in concentration smaller than ± 1.0% of the LEL concentration of the substance being measured. Because percent LEL detectors are poor indicators for the presence of many VOCs, lack of a reading is not necessarily proof of the absence of hazard.

Although catalytic-bead sensors may have limitations with concern to the measurement of toxic VOCs at exposure limit concentrations, they are by far the most widely used and dependable method for measuring Methane and other combustible gases and vapours with smaller, lighter molecules.

Increasing concern with the toxicity of VOCs has led to a number of newly revised exposure limits, including the TLVs® for diesel vapour, kerosene and gasoline. Because the safety procedures for many international corporations are tied to the most conservative published standard, these new TLVs® have been receiving a lot of attention around the World. The TLV® for diesel vapour adopted in 2002 has proven to be particularly problematic, and has led to the revision of numerous oil industry, maritime, and military health and safety monitoring programmes. The ACGIH TLV® species an 8-hour TWA for total diesel Hydrocarbons (vapour and

aerosol) of 100 mg/m3. This is equivalent

to approximately 15 parts-per-million diesel vapour. For diesel vapour, 1% LEL is equivalent to 60 PPM. Even if the instrument is properly calibrated for the detection of diesel - which is not possible for many designs - a reading of only 1% LEL would exceed the TLV® for diesel by 600 percent!

It goes beyond the scope of this article to argue how long it might be permissible to remain at 5% or 10% LEL without actually exceeding the 8-hour. TWA or STEL. What is most striking about the list is how few VOCs have 8-hour TWA exposure limits higher than 5% LEL. None of the VOCs on the list have exposure limits higher than 10% LEL.

molecule contains, the lower the IP. Thus, in general, the larger the molecule, the easier it is to detect! This is exactly the opposite of the performance characteristics of the catalytic hot-bead type combustible sensor.

Photoionisation detectors are easily able to provide readings at or below the OEL or TLV® for all of the VOCs listed in Table 1, including diesel. The best approach to VOC measurement is often a multi-sensor instrument equipped with both LEL and PID sensors.

Multi-sensor detectors with PIDs

Catalytic hot-bead combustible sensors and photoionisation detectors represent complementary, not competing detection techniques. Catalytic hot-bead sensors are excellent for the measurement of Methane, Propane, and other common combustible gases that are not detectable by means of a PID. On the other hand, PIDs can detect large VOC and Hydrocarbon molecules that are effectively undetectable by hot-bead sensors, even when they are operable in PPM measurement ranges.

The best approach to VOC measurement in many cases is to use a multi-sensor instrument capable of measuring all the atmospheric hazards that may be potentially present. Having a single instrument equipped with multiple sensors means no condition is accidentally overlooked.

Reliance on hot-bead type LEL sensors for measurement of VOC vapours means in many cases that the OEL, REL or TLV® is exceeded long before the concentration

of vapour is sufcient to trigger the

combustible hazardous condition threshold alarm. When toxic VOCs are potentially present it is necessary to use additional or different detection techniques that are better suited for direct measurement of VOCs at PPM toxic exposure limit concentrations. Photoionisation detectors are becoming increasingly popular for this application.

It should be noted that other combustible gases and vapours may be present at the same time as toxic VOCs.

Using Photoionisation detectors to measure VOCs

Photoionisation detectors use high-energy ultraviolet light from a lamp housed within the detector as a source of energy used to remove an electron from neutrally charged

VOC molecules, producing a ow of electrical

current proportional to the concentration of contaminant. The amount of energy needed to remove an electron from the target

molecule is called the Ionisation Potential (IP)

for that substance. The larger the molecule, or the more double or triple bonds the

Page 72

Portable Gas Detectors (continued)

Maintaining portable gas detectors

Both eld serviceable and disposable

portable gas detectors will require ongoing maintenance and care throughout their operational lives, although requirements are greatly reduced for disposable units. In general, there are three core activities that will need to be undertaken:

• Functional device testing: This quick test (also known as bump testing) is carried out to ensure that a portable gas detector responds correctly, i.e. goes into alarm in the presence of a known gas concentration. It is the only way of knowing a portable detector is working correctly and for this reason, best-practice recommendation is to carry out a daily bump test (please see How to perform a bump test on page 73 for detailed

information).

- Bump testing is applicable to both eld

serviceable devices and disposable portable gas detectors

• Calibration: A calibration is usually carried out twice yearly (although it may be undertaken more or less frequently in specic applications). This procedure is designed to ensure that a portable gas detector’s readings are truly representative of actual gas concentrations in the atmosphere. This is particularly important when dangerous gases like Hydrogen Sulphide may be present, because just 1,000 PPM of this gas is enough to kill in a single breath, therefore incorrect readings could cause severe injury or even death.

- This activity is applicable to eld

serviceable devices only

• Sensor replacement: Sensors have a dened expiry and must be replaced after this period runs out. The average life of sensors is approximately 2-3 years but it is worth remembering that sensors may need to be replaced more frequently when

“known poisons” are present, e.g. Silicone poisoning catalytic bead ammable detection sensors. Depending on the type of device, sensors may be replaced individually or as part of an integrated cartridge (as used by devices like the

Impact range from Honeywell Analytics).

- This activity is applicable to eld

serviceable devices only

• Datalogging: Although it is not considered maintenance, datalogging is often legislatively driven or imposed by insurance companies and involves the logging and documenting of portable gas detector readings; especially when alarm events occur.

- This activity is applicable to both eld serviceable devices and disposable portable gas detectors

72 www.honeywellanalytics.com / www.gasmonitors.com

Page 73

Portable Gas Detectors (continued)

Reducing the cost of device testing

When it comes to device bump testing and datalogging, automatic test and datalogging stations like those produced by Honeywell can greatly reduce the cost and time associated with ongoing device care. In fact, total labour and cost savings can be reduced by as much as 40-60% (dependent on the

application and site-standards). A test and

datalogging solution from Honeywell can add the following value:

• Minimise training by providing an intuitive, single-button operation solution

• Reduce bump testing time by up to 80%

(when compared with a manual method)

• Controls all gas concentrations, preventing too much gas being used, thus potentially reducing test gas costs

• Datalogging with a single button press (no

need for PCs)

• No need for additional accessories such as gas bottles, tubing, regulators etc

MicroDock II Enforcer IQ6 Docking Station

How to perform a manual bump test

If a test station is not desired, operators can carry out bump testing manually in the following way, using a portable unit and test kit accessories:

- Attach one end of the hose to the regulator of the gas cylinder and the other end to the bump test and calibration cap

- Then attach the bump test and calibration cap to the device

- Apply a short 3 second blast of gas to the device

- The unit should go into alarm. If the device fails to alarm, it will need to be calibrated

- Close the regulator and remove the calibration cap from the device. The unit will continue to alarm until the gas clears from the sensors

- The hose can then be disconnected from the calibration cap and stored in a safe, contaminant-free location

Many devices today, including those built by Honeywell, are optimised to deliver not only user-friendly operation but fail-safe reminders that ensure important maintenance needs are undertaken when required. For example,

BW Technologies by Honeywell’s range of portable gas detectors remind of aspects like a “need to bump test or calibrate”, followed by “forced bump testing” or “forced calibration”, which prevents the device from being used until the necessary activity has been performed. These aspects can be factory-set

in order to meet specic site standards, i.e.

no more than 180 days between calibrations. Such aspects can be further enhanced by BW Technologies by Honeywell’s IntelliFlash technology (please see Value-added visual status indication on page 59 for detailed information on IntelliFlashTM technology).

What drives device maintenance?

It’s important to remember that portable devices are considered safety-critical and this means that they are designed and maintained

in accordance with specic legislated

directives and standards. With safety-critical products and processes, risk potential is mitigated wherever possible. There are legislated requirements to check devices

(bump test) and calibrate them, depending

on the application. This requirement explains the long period of operation that

a disposable product can have (with no

need for calibration) over a eld device. In

reality, both are designed to the same high

standards, and the calibration of the eld

device is not attributed to any difference in its constituent parts, but driven by compliance and mitigating the risk that the device may drift and not be representative of true readings. With this in mind, many hazardous applications are not legislatively allowed to use disposable units.

It is essential to take a holistic approach when considering portable gas detection and a suitable device will depend upon not

only specication and site needs but also

legislative requirements.

Page 74

Portable Gas Detectors (continued)

Experts in Gas Detection

Portable gas detection from Honeywell

Honeywell produces a wide variety of portable devices designed to meet the application monitoring needs of diverse industries; from low-cost, disposable compliance units to functionality-rich, high

specication devices.

GasAlertClipExtreme

Compact and affordable, GasAlertClipExtreme offers 24/7 monitoring of single gas hazards with zero maintenance requirements. With easy on/off operation, this single gas detector is available in two and three year model variants.

GasAlertExtreme

Compact and affordable, GasAlertExtreme reliably monitors for any single toxic gas hazard. With easy on/off operation, this single gas detector offers extended longevity with a

two year eld-replaceable battery and sensor.

GasAlertQuattro

Rugged and reliable, the GasAlertQuattro 4-gas detector combines a comprehensive range of features with simple one-button operation. The graphic LCD displays easy to identify icons that indicate operational information, such as bump test and calibration

status for simplied on-site auditing.

The slim and compact GasAlertMicroClip XT provides affordable protection from atmospheric hazards. With simple one-button operation, this device offers ultimate ease

of use and signicantly reduces time spent

training the user.

The rugged GasAlertMax XT II monitors up to four gas hazards and combines

straightforward one-button eld operation

with an integrated sampling pump. Tamper-proof, user-adjustable options enable the instrument to be customised to suit application needs.

Compact and lightweight, GasAlertMicro 5 Series instruments are available in diffusion or pumped formats. These portable gas detectors simultaneously

monitor and display up to ve atmospheric

hazards. Model variants include the GasAlertMicro 5 PID model for the low-level detection of VOCs and GasAlertMicro 5 IR for Carbon Dioxide monitoring.

A compact and rugged single-gas toxic portable detector with one-button simplicity, continuous real-time display and highly visible/audible alarms for high noise locations. ToxiPro® features an integrated black box data recorder and event logger as standard (compatible with the Honeywell

IQ Express Single Gas Docking Station).

GasAlertMicroClip XT

GasAlertMax XT II

GasAlertMicro 5 Series

ToxiPro

MultiPro

4-gas device with real-time simultaneous readings, simple one-button operation and a large easy-to-read LCD display. MultiPro features an integrated black box data recorder and event logger as standard. An optional screw-on pump with automatic leak

test and low ow alarm is also available.

(Compatible with the Honeywell IQ Express

Multi-Gas Docking Station).

PHD6

Simultaneous monitoring of up to 6-gas hazards with 18 sensor choices, including PID for the low-level detection of Carbon Dioxide and Methane. PHD6TM features an integrated black box data recorder and event logger that records all atmospheric hazards experienced during operation. (Compatible with the

Honeywell IQ6 Multi-Gas Docking Station).

Impact range

Honeywell Analytics

Experts in Gas Detection

High specication, 4-gas simultaneous

monitoring solution designed to meet the needs of the most challenging applications. Model variants include Impact Pro, which features an integrated automatic pump,

Impact IR and Impact (standard).

Impulse XT

Honeywell Analytics

Impulse XT is a single-gas portable detection solution with zero maintenance requirements. Delivering 24/7 monitoring with a two year operational life, this device also features an IP67 rating making it ideal for challenging environments.

74 www.honeywellanalytics.com / www.gasmonitors.com

Page 75

Portable Gas Detectors (continued)

Experts in Gas Detection

Automatic device testing solutions from Honeywell

MicroDock II

The MicroDock II is an easy, cost-effective way to bump test, calibrate and charge a device as well as manage records. Fully compatible with the complete BW Technologies by Honeywell product range, its accompanying Fleet Manager II software allows the user to download information faster than ever from the MicroDock II. Improved functionality allows the creation of accurate and user-friendly reports, print receipts of calibration, sort and graph data and archive information, helping

to dramatically simplify eet management

activities.

Enforcer

Honeywell Analytics

Designed for use with the Impact range of portable gas detectors, Enforcer is a small, lightweight test and calibration station that is fully portable. With no batteries or mains power required, Enforcer permits quick testing on the move and helps to reduce the ongoing cost of portable device maintenance.

ToxiPro IQ Express Docking Station

A fully automated bump test, calibration and datalogging station for use with the ToxiPro portable range, allowing four devices to be linked to a single gas supply. Connects to a

PC via USB port or Ethernet (optional).

Multi-Pro IQ Express Docking Station

A fully automated bump test, calibration and datalogging station for use with the MultiProTM range of portable gas detectors. Connects to

a PC via USB port or Ethernet (optional).

IQ6 Docking Station

A fully automated bump test, calibration and datalogging station for use with the PHD6TM range of portable gas detectors. Connects to

a PC via USB port or Ethernet (optional).

Page 76

North American

Hazardous Area Standards and Approvals

The North American

system for the

certication,

installation and inspection of hazardous locations equipment includes the following elements:

• Installation Codes

– E.g. NEC, CEC

• Standard Developing Organisations (SDOs)

– E.g. UL, CSA, FM

• Nationally Recognised Testing Laboratories (NRTLs)

– Third Party Certiers e.g. ARL, CSA, ETI, FM, ITSNA, MET, UL

• Inspection Authorities

– E.g. OSHA, IAEI, USCG

he installation codes used in North America are the NEC 500 and NEC 505 and the

for Canada. In both countries these guides are accepted and used by most authorities as

the nal standard on installation and use of

electrical products. Details include equipment construction, performance and installation

requirements, and area classication

requirements. With the issuance of the new NEC these are now almost identical.

The Standards Developing Organisations

(SDOs) work with industry to develop the

appropriate overall equipment requirements. Certain SDOs also serve as members of the technical committees charged with the development and maintenance of the North American installation codes for hazardous locations.

CEC (Canadian Electric Code)

The Nationally Recognised Testing

Laboratories (NRTLs) are independent third party certiers who assess the

conformity of equipment with these requirements. The equipment tested and approved by these agencies is then suitable for use under the NEC or CEC installation standards.

In the United States of America the inspection authority responsible is OSHA (Occupational

Safety and Health Administration). In Canada

the inspection authority is the Standards

Council of Canada. To conrm compliance to

all national standards both countries require an additional indication on products tested and approved.

As an example CSA approved product to USA standards must add NRTL/C to the CSA symbol. In Canada, UL must add a small c to its label to indicate compliance to all Canadian standards.

www.honeywellanalytics.com / www.gasmonitors.com76

Page 77

North American Ex Marking and Area Classication

Once approved, the equipment must be marked to indicate the details of the approval.

Class I – Explosive Gases

Division 1 Gases normally present in explosive amounts Division 2 Gases not normally present in explosive amounts

Gas Types by Group

Group A Acetylene

Group B Hydrogen

Group C Ethylene and related products Group D Propane and alcohol products

Class II – Explosive Dusts

Division 1 Dust normally present in explosive amounts

Division 2 Dust not normally present in explosive amounts

Dust Types by Group

Group E Metal dust

Group F Coal dust

Group G Grain and non-metallic dust

Page 78

European Hazardous Area Standards and Approvals

The standards used in most countries outside of North America are IEC/CENELEC and ATEX. The IEC (International

Electrotechnical Commission) has set detailed standards for

equipment and classication of areas and is the standard that countries outside of both Europe and North America use. CENELEC (European Committee for Electrotechnical

Standardisation) is a rationalising group that uses IEC

standards as a base and harmonises them with all ATEX

standards and the resulting standards legislated by member

countries, which are based upon ATEX.

he CENELEC mark is accepted

in all European Community (EC)

countries.

All countries within the EC also have governing bodies that set additional standards for products and wiring methods. Each member country of the EC has either government or third party laboratories that test and approve products to IEC and/or CENELEC standards. Wiring methods change even under CENELEC, this is primarily as to the use of cable, armoured cable, and type of armoured cable or conduit. Standards can change within a country “and referred as National Differences” depending on the location or who built a facility. Certied apparatus carries the ‘Ex’ mark.

Key

CENELEC Members CENELEC Affiliate Water mass

ICELAND

REPUBLIC OF

IRELAND

UNITED

KINGDOM

German

FRANCE

NETHERLANDS

78 www.honeywellanalytics.com

www.honeywellanalytics.com / www.gasmonitors.com

Approved National Test Houses which are cited in the EC Directives may use the EC Distinctive Community Mark:

PORTUGAL

SPAIN

Note: This is not a

Certication Mark

Page 79

RUSSIA

CENELEC mEmbEr CouNtriEs:

BELGIUM

LUX

NORWAY

DENMARK

GERMANY

SWEDEN

BALTIC SEA

CZECH REPUBLIC

POLAND

SLOVAKIA

FINLAND

ESTONIA

LITHUANIA

LATVIA

BELARUS

Austria Belgium Bulgaria Croatia Cyprus Czech Republic Denmark Estonia Finland France Germany

UKRAINE

MOLDOVA

Greece Hungary Iceland Ireland Italy Latvia Lithuania Luxembourg Malta Netherlands Norway

Poland Portugal Romania Slovakia Slovenia Spain Sweden Switzerland United Kingdom

SEA OF

AZOV

SWITZ

ITALY

AUSTRIA

SLOVENIA

HUNGARY

CROATIA

BOSNIA

ROMANIA

BLACK SEA

SERBIA

BULGARIA

MACEDONIA

TURKEY

ALBANIA

GREECE

CYPRUS

Page 80

ATEX

GAS

FACT

ATEX (an abbreviation of

ATmospheres EXplosibles)

sets the minimum safety

ATEX = ATmospheres EXplosibles

There are two European Directives that have been law since July 2003 that detail the manufacturers and users obligations regarding the design and use

of apparatus in hazardous atmospheres.

Responsibility Directive Article

Manufacturer 94/9/EC ATEX 95 ATEX 100a

End Users/Employers 99/92/EC ATEX 137

standards for both the

Employer and Manufacturer

regarding explosive

atmospheres

he ATEX directives set the MINIMUM standards for both the employer and manufacturer

It is the responsibility of the employer to conduct an assessment of explosive risk and to take necessary measures to eliminate or reduce the risk.

ATEX DIRECTIVE 94/9/EC ARTICLE 100A

Article 100a describes the manufacturer’s responsibilities:

• The requirements of equipment and protective systems intended for use in potentially explosive atmospheres (e.g. Gas

Detectors)

• The requirements of safety and controlling devices intended for use outside of potentially explosive atmospheres but required for the safe functioning of equipment and protective systems (e.g.

Controllers)

• The Classication of Equipment Groups into