Ion Science MiniPID User Manual
Unrivalled Detection. www.ionscience.com
MiniPID 3PIN
Instrument User Manual V2.1
Part number: 846236
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Part number: 846236
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Declaration of conformity
Manufacturer: Ion Science Ltd, The Way, Fowlmere, Cambridge, SG8 7UJ, UK
Product: MiniPID Std or MiniPID Reg
Product Description: Intrinsically safe photo-ionisation sensor for volatile organic compounds
Directive 94/9/EC ATEX
Identification: II 1G Ex ia IIC T4 (-40
(-40
o
C ≤ Ta ≤ +65
o
C) @ 0.9W limitation
o
C ≤ Ta ≤ +55
o
C) @ 1.1W limitation
Notified Body: Baseefa Ltd, 1180, Buxton, UK
Intertek, Cortland, NY 13045, USA
EC Type Examination Certificate(s)
Baseefa07ATEX0060U – latest supplement Baseefa 07ATEX0060U-6 issued 8th February 2013
Ref Baseefa Cert Report 07(A) 0688, 10(T) 0168
IECEx BAS 07.0030U – latest revision No 6 issued 8th February 2013
Ref IECEx Text Reports GB/BAS/EX TR07.0056/00 TR07.0146/00 TR07.0181/00
TR08.0135/00 TR03.0195/00
ETL & cETL Test Report No. 3176983CRT-003 Issued May 2010
Standards
BS EN 60079-0:2006 Electrical Apparatus for Potentially Explosive Atmospheres – General Requirement
BS EN 60079-11:2007 Explosive Atmospheres - Equipment Protection by Intrinsic Safety ‘i’
BS EN 61010-1:2010 Safety requirements for electrical equipment for measurement, control and laboratory
use – General requirements
UL913; 2nd Edition Intrinsically safe apparatus and associated apparatus for use in Class I, II, III,
Division 1, Hazardous (Classified) Locations
CSA-C22.2 No157-92 Intrinsically safe and non-incendive equipment for use in Hazardous Locations
(Update 2)
Other Standards
BS EN ISO 9001:2008 Quality Management Systems – Requirements
BS EN 13980:2002 Potentially Explosive Atmospheres – Application of Quality Systems
On behalf of Ion Science Ltd, I declare that, on the date this product accompanied by this declaration is
placed on the market, the product conforms with all technical and regulatory requirements of the above listed
directives.
Name: Mark Stockdale Position: Technical Director
Signature: Date: 11th August 2010 Doc. Ref. 846238
issue
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MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Contents
Declaration of conformity ............................................................................................................................... 3
Statements ....................................................................................................................................................... 5
Responsibility for Use .................................................................................................................................... 5
Introduction ...................................................................................................................................................... 6
Applications ..................................................................................................................................................... 6
Features ............................................................................................................................................................ 6
How does it work? ........................................................................................................................................... 7
What is a volatile organic compound (VOC)? ................................................................................................ 7
What is a response factor? ............................................................................................................................ 8
Physical properties .......................................................................................................................................... 9
Mechanical installation ................................................................................................................................. 10
Sealing the MiniPID ...................................................................................................................................... 10
Electrical Installation ..................................................................................................................................... 12
Selecting the correct supply voltage for your MiniPID ................................................................................. 12
Power-up surge ............................................................................................................................................ 13
Analogue output ........................................................................................................................................... 13
Error states (units shipped beginning 2009) ................................................................................................ 13
Zero offset correction ................................................................................................................................... 13
PCB layout for EMC noise reduction ........................................................................................................... 14
Temperature correction ................................................................................................................................ 15
Schematic Block diagram............................................................................................................................. 17
Intrinsic Safety circuit implementation .......................................................................................................... 17
Specification .................................................................................................................................................. 18
Common Electrical Specifications: ............................................................................................................... 18
Gas Detection Specifications (specific): ....................................................................................................... 19
Environmental Effects ................................................................................................................................... 21
Natural physical effects of humidity ............................................................................................................. 21
Maintenance ................................................................................................................................................... 22
When does my MiniPID require maintenance? ........................................................................................... 22
When do I clean the MiniPID lamp? ............................................................................................................. 22
When do I replace the MiniPID electrode pellet? ......................................................................................... 22
When do I replace the MiniPID lamp? ......................................................................................................... 22
Removing Mini Pellet and Lamp .................................................................................................................. 22
Cleaning the MiniPID Lamp ......................................................................................................................... 23
Re-fitting MiniPID pellet and lamp ................................................................................................................ 24
Instrument warranty and service ................................................................................................................. 24
Warranty ....................................................................................................................................................... 25
Service ......................................................................................................................................................... 25
Contact Details ............................................................................................................................................. 25
Manual log ...................................................................................................................................................... 27
Page 4 of 27
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Statements
Responsibility for Use
Inadequate performance of the gas detection equipment described in this manual may not necessarily be
self-evident and consequently equipment must be regularly inspected and maintained. Ion Science
recommends that personnel responsible for equipment use institute a regime of regular checks to ensure it
performs within calibration limits, and that a record be maintained which logs calibration check data. The
equipment should be used in accordance with this manual, and in compliance with local safety standards.
Legal Notice
Whilst every attempt is made to ensure the accuracy of the information contained in this manual, Ion Science accepts no liability for errors or omissions, or any consequences
deriving from the use of information contained herein. It is provided "as is" and without any representation, term, condition or warranty of any kind, either express or implied. To
the extent permitted by law, Ion Science shall not be liable to any person or entity for any loss or damage which may arise from the use of this manual. We reserve the right at any
time and without any notice to remove, amend or vary any of the content which appears herein.
Page 5 of 27
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Features
Patented guard electrode for excellent
humidity immunity
Reliable lamp – illuminates at low
temperatures
Superior lamp life
User-replaceable electrode pellet keeps
your PID working, even after bad
contamination
Intrinsically safe (ATEX, IECEx, ETL, CETL)
Bulb out error detection (MiniPID PPM only)
Applications
Industrial hygiene & safety
monitoring
Soil contamination and remediation
Hazmat sites and spills
Low concentration leak detection
EPA Method 21 and emissions
monitoring
Arson investigation
Indoor air quality monitoring
Introduction
MiniPID is a miniature photoionisation sensor.
Sample gas freely diffusing through the filter
membrane is exposed to deep ultraviolet light
generated by a lamp within the sensor. The
emitted light ionises targeted gases in the
sample so they can be detected by the gas
detector and reported as a concentration (eg
ppb, ppm or mg/m3).
Chemicals such as volatile organic compounds
(VOCs) with an ionisation potential less than or
equal to 10.6 eV will be detected by the
MiniPID.
The MiniPID can be installed in portable and stationary gas monitors that accept either Alphasense Ltd
CH-A3 or City Technology
same dimensional and electrical profile as pellistors (provided the electronics input circuit is designed to take
the sensor’s output range). This opens up an incredible variety of environmental and safety applications in
industrial, commercial and residential markets.
The MiniPID sensor is offered in two models having the guaranteed range of operation below. They are
virtually insensitive to humidity changes, providing unparalleled performance in a variety of applications.
The MiniPID PPM has a dynamic range of <100 ppb to >6,000 ppm (isobutylene).
The MiniPID PPB has a linear dynamic range of 1 ppb to >50 ppm (isobutylene).
Please contact Ion Science at www.ionscience.com for a comprehensive list of response factors for various
VOCs.
The MiniPID sensor pack includes a sensor incorporating a 10.6 eV lamp, lamp driver, amplifier circuitry and
removable electrode pellet with particulate filter and pellet removal tool.
TM
4P pellistor cells, providing complete PID capability in a package that has the
Page 6 of 27
TM
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Lamp gas, eg
krypton
Lamp
window
Test gas
Lamp
body
Fence electrode
2
2b
2a
Y
X
+
Photon
Copyright Ion Science Ltd, 2007
To cathode
Y -
How does it work?
The Ion Science MiniPID measures volatile organic compounds (VOCs) in air by photoionisation detection
(PID), which is shown schematically below. Test gas (1) is presented to the membrane filter at the top of the
photoionisation cell and freely diffuses into and out of the underlying chamber formed by the filter, housing
walls, and a UV lamp window. The lamp emits photons (shown by arrows) of high energy UV light,
transmitted through the window. Photoionisation occurs in the chamber when a photon is adsorbed by the
molecule, generating two electrically charged ions, one positively charged, X+, and one negatively charged,
Y- (2a). An electric field, generated between the cathode and anode electrodes, attracts ions (2b). The
resulting current, which is proportional to the concentration of the VOC, is measured and used to determine
the gas concentration. The MiniPID includes a third fence electrode (patented) to ensure that the amplified
current does not include significant contributions due to other current sources such as water condensation on
the chamber walls.
What is a volatile organic compound (VOC)?
A volatile organic compound, or VOC, is a carbon-containing chemical, which is significantly or completely
vaporised at ambient temperatures.
What volatile organic compound (VOCs) are sensed by MiniPID?
Most VOC’s can be detected by MiniPID. Notable exceptions are low molecular weight hydrocarbons. Each
VOC has a characteristic threshold energy of light (photon energy) which, when directed at the VOC, causes
it to fragment into ions. This is called the Ionisation Potential, or IP. VOCs are ionised (and hence detected) if
light of photon energy greater than the IP interacts with the gas sample. The peak photon energy generated
in a detector depends on the PID lamp used: Krypton = 10.6 eV or Argon = 11.7 eV. Hence, the use of an
argon lamp leads to detection of the largest range of volatile compounds, while using a Xenon lamp can
increase selectivity. Lamps of a particular type do not typically vary in spectral fingerprint, so relative
responses to a particular gas, eg benzene, to a particular lamp, e.g. krypton, does not vary from lamp to
lamp. However, the intensity of lamps does vary to some extent, leading to a difference in absolute
response to the calibration gas.
Sufficient volatility of a compound is also essential for measurement by PID as with any other detector. A
fairly large molecule such as alpha pinene, (a constituent of turpentine), saturates in air at about 5000 ppm
at 20oC; this is the maximum concentration at which the compound will usually be detected. Some
compounds, for example, machine oils and agrochemicals - generate only a few ppm of vapour at ambient
temperatures; it is more difficult to detect these compounds in air. ‘MiniPID response factors’ Application
Note lists VOCs by their common name and their sensitivity to a Krypton lamp, the most common lamp and
the lamp supplied with the MiniPID PPM and MiniPID PPB.
X
Page 7 of 27
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Chemical name
RF
Fractional composition
Isopropanol
4.4
0.2
Acetone
0.7
0.8
Response Factors
What is a response factor?
Our PIDs are calibrated using isobutylene, but the PID is a broadband VOC detector with a sensitivity that
differs for each VOC. Response Factors are used to compensate for these differing sensitivities.
A response factor (RF) is a number which relates the MiniPID response to a particular VOC relative to
isobutylene. If you know what VOC you are measuring then multiplying the displayed concentration by the
RF of the VOC will result in the actual concentration of VOC.
Example: Toluene
A sensor is calibrated using isobutylene and found to have a sensitivity of 1 mV ppm-1.
If the sensor is exposed to 100 ppm isobutylene the output will be 100 mV.
Toluene is known to generate twice the response of isobutylene.
In order to correct the toluene response it is multiplied by the response factor for toluene of 0.5.
If the sensor is exposed to 100 ppm toluene then the displayed uncorrected concentration will be 200
ppm isobutylene. The corrected concentration would be 200 multiplied by the RF, 0.5, which gives the
correct result of 100 ppm toluene.
If response factors are programmed into an instrument, you are able to specify a volatile compound, and the
instrument will internally compensate for the response factor corresponding to that volatile, and display and
record the corrected volatile concentration.
VOC mixtures
Occasionally you will be measuring a mixture of VOCs. If the total concentration is within the linear range of
the PID, then it is reasonable to assume that the concentrations are additive without interference between
the different VOCs:
The correction factor for a gas mix containing PID detectable gases A, B, C… with response factors RF(A),
RF(B), RF(C), in fractional proportions a:b:c is given by:
RF mix = a/RF(A) + b/RF(B) + c/RF(C)…
Example:
A gas mix to be monitored contains 1 part isopropanol to 4 parts acetone:
Therefore the RF of the mix will be:
RF mix = (4.4 x 0.2) + (0.7 x 0.8)
= 0.88 + 0.56
= 1.44
Important: remember that if you are measuring a combination of VOCs then accurate measurement of one
of these VOCs will be difficult; without careful data analysis, you will get only a RF averaged measurement.
Be cautious when reporting actual VOC concentration if you know that there may be several VOCs present.
Page 8 of 27
MINIPID 3PIN MANUAL Ion Science Ltd
Unrivalled Detection. www.ionscience.com
Patents:
US 7,046,012
EC 1474681
Input power:
3.3 V+ 0.3 V / - 0.2 V. Stable (noise free)
3.6 V to 10 V (IS) or 18 V (safe zone).
120mA max power-up surge for 0.3s
33mA typical under continuous operation
Ion Science Standard Versions:
MP3SM6LB MiniPID 3-pin ppm
(3V to 3.6V certified)
MP3SM6LC MiniPID 3-pin ppm
(3.6V to 10V certified)
MP3SM6LN MiniPID 3-pin ppm
(3.6V to 18V non certified)
MP3SB6FB MiniPID 3-pin ppb
(3V to 3.6V certified)
MP3SB6FC MiniPID 3-pin ppb
(3.6 to 10V certified)
MP3SB6FN MiniPID 3-pin ppb
(3.6 to 18V non certified)
LEL equivalent
mechanical format
Base view
Outside dimensions and pin
configuration as per industry
standard series 4 LEL sensor
Pin Details
1 Positive Supply Voltage
2 Signal Output
3 0V Ground
Hazardous Locations Approvals:
ATEX Approved Baseefa 07ATEX0060U
IECEx Approved BAS07.0030U
II 1G Ex ia IIC T4
Intertek
Class 1 Div 1 Groups A, B, C, D T4
Conforms to UL standard 913
Certified to CSA standard C22. 2 No. 157
-40°C ≤ Ta ≤ 55°C 1.1 W (to 65°C @ 0.9 W)
Version MAY 2010
Physical properties
Note: Hashed area is the preferred sealing location for an O’Ring.
Bullet points of distinction:-
Page 9 of 27
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