Rosemount 400A Hydrocarbon Analyzer-Rev K (Cat # 194106 / Serial # beginning with 2000001) Manuals & Guides

Rosemount Analytical

M

ODEL

H

YDROCARBON ANALYZER

I

NSTRUCTION MANUAL

748262-K

NOTE

HIS MANUAL IS APPLICABLE TO MODEL

T

WITH SERIAL NUMBERS BEGINNING WITH

400A

400A, C

ATALOG NUMBER

2000001

194106

OTICE

N

The information contained in this document is subject to change without notice.

Teflon® is a registered trademark of E.I. duPont de Nemours and Co., Inc.
SNOOP

®

is a registered trademark of NUPRO Co.

Instruction Manual 748262-K
July 1997
Printed in USA

Rosemount Analytical Inc.

4125 East La Palma Avenue
Anaheim, California 92807-1802

C

ONTENTS

PREFACE

SAFETY SUMMARY ..........................................................................................P-1

SPECIFICATIONS..............................................................................................P-3

CUSTOMER SERVICE, TECHNICAL ASSISTANCE AND FIELD SERVICE....P-5

RETURNING PARTS TO THE FACTORY.........................................................P-5

TRAINING ......................................................................................................P-5

DOCUMENTATION............................................................................................P-5

S

ECTION

1.1 DESCRIPTION.........................................................................................1-1

1.2 ANALYZER MOUNTING OPTIONS.........................................................1-1

1.3 FUEL GAS OPTIONS...............................................................................1-2

1.4 OUTPUT OPTIONS..................................................................................1-3

1.5 SAMPLE PUMP OPTION.........................................................................1-4

1.6 GAS SAFETY FEATURES.......................................................................1-4

1. I

1.4.1 Isolated Remote Range Change and Identification....................1-4

1.4.2 Range Trim Option......................................................................1-4

NTRODUCTION

SECTION 2. INSTALLATION

2.1 UNPACKING............................................................................................2-1

2.2 LOCATION...............................................................................................2-1

2.3 VOLTAGE REQUIREMENTS...................................................................2-1

2.4 FUEL AND AIR REQUIREMENTS...........................................................2-2

2.4.1 Fuel Gas.....................................................................................2-2

2.4.2 Air ......................................................................................2-3

2.5 SAMPLE HANDLING................................................................................2-3

2.6 GAS CONNECTION.................................................................................2-4

2.7 LEAK CHECK...........................................................................................2-6

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

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ONTENTS

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SECTION 2. (CONTINUED)

2.8 ELECTRICAL CONNECTIONS ............................................................... 2-6

2.8.1 Line Power Connections ............................................................ 2-6

2.8.2 Voltage Output Selection and Cable Connections for

Recorder....................................................................... 2-7

2.8.3 Voltage to Current Output Board (optional)................................ 2-7

2.8.4 Auxiliary Contacts....................................................................... 2-7

2.8.5 Remote Range Control and Indication....................................... 2-7

2.8.6 Sample Pump Accessory........................................................... 2-9

SECTION 3. STARTUP AND CALIBRATION

3.1 INITIAL STARTUP AND CALIBRATION.................................................. 3-1

3.1.1 Selection of Calibration Method and Assoicated Standard

Gas(es)......................................................................... 3-4

3.2 CALIBRATION PROCEDURE................................................................. 3-5

3.3 RANGE SWITCH..................................................................................... 3-7

3.4 RANGE TRIM OPTION............................................................................ 3-8

SECTION 4. OPERATION

4.1 ROUTINE OPERATION........................................................................... 4-1

4.2 RECOMMENDED CALIBRATION FREQUENCY.................................... 4-1

4.3 SHUTDOWN............................................................................................ 4-1

4.4 OBTAINING MAXIMUM SENSITIVITY.................................................... 4-2

S

ECTION

5.1 PRINCIPLE OF OPERATION.................................................................. 5-1

5.2 BURNER.................................................................................................. 5-1

5.3 ANALYZER FLOW SYSTEM................................................................... 5-4

5.4 PREAMPLIFIER BOARD......................................................................... 5-4

5.5 MAIN ELECTRONICS BOARD................................................................ 5-5

5. T

5.2.1 Response to Different Hydrocarbons......................................... 5-2

5.5.1 Post Amplifier............................................................................. 5-5

5.5.2 Digital Display............................................................................. 5-5

5.5.3 Span ..................................................................................... 5-6

5.5.4 Remote Range Control............................................................... 5-6

HEORY

5.5.3.1 Range Trim (Option)................................................... 5-6

5.6 HEATER/FAN TEMPERATURE ASSEMBLY.......................................... 5-6

ii

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

SECTION 5. (CONTINUED)

5.7 IGNITION CIRCUIT..................................................................................5-7

5.8 SYSTEM POWER SUPPLIES ..................................................................5-7

5.9 FLAME-OUT BOARD...............................................................................5-8

SECTION 6. SERVICE AND TROUBLESHOOTING

6.1 SYSTEM CHECKOUT..............................................................................6-1

6.2 SERVICING FLOW SYSTEM AND BURNER..........................................6-2

6.2.1 Burner Disassembly and Cleaning..............................................6-3

6.2.2 Thermistor...................................................................................6-4

6.2.3 Fuel and Air Restrictors ..............................................................6-4

6.2.4 Sample Capillary.........................................................................6-4

6.3 TROUBLESHOOTING .............................................................................6-4

SECTION 7. REPLACEMENT PARTS

ONTENTS

C

7.1 CIRCUIT BOARD REPLACEMENT POLICY ...........................................7-1

7.2 RECOMMENDED REPLACMENT PARTS LIST......................................7-1

ENERAL PRECAUTIONS FOR HANDLING

G

ARRANTY

W

IELD SERVICE AND REPAIR FACILITIES

F

TORING HIGH PRESSURE CYLINDERS

& S

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

iii

ONTENTS

C

FIGURES

2-1 Range Input-Output Board....................................................................... 2-8

2-2 Range Control and Output Connections.................................................. 2-10

3-1 Power Switch Location............................................................................. 3-2

3-2 Typical Curves of Downscale Response vs. Time for Various

Hydrocarbons............................................................................... 3-5

3-3 Example 1 Display................................................................................... 3-7

3-4 Example 2 Display................................................................................... 3-8

3-5 Example 3 Display................................................................................... 3-8

3-6 Range Trim Option Schematic................................................................. 3-9

4-1 Typical Curve of Analyzer Response vs. Pressure Setting on Sample

Pressure Regulator....................................................................... 4-2

4-2 Typical Curves of Analyzer Response vs. Pressure Setting on Fuel Pressure

Regulator...................................................................................... 4-3

4-3 Typical Curves of Analyzer Response vs. Pressure Setting on Air

Pressure Regulator....................................................................... 4-3

5-1 Flame Ionization Detection Theory.......................................................... 5-1

5-2 Typical Curves of Downscale Response vs. Time for Various

Hydrocarbons............................................................................... 5-2

TABLES

1-1 Fuel Gas vs. Analyzer Characteristics..................................................... 1-3

2-1 Range Control.......................................................................................... 2-8

3-1 Internal Pressure Regulators Settings..................................................... 3-2

3-2 Range Switch Settings............................................................................. 3-7

5-1 Approximate Effective Carbon Numbers.................................................. 5-3

5-2 Input Sensitivities..................................................................................... 5-5

5-3 Fullscale Sensitivity.................................................................................. 5-6

6-1 Troubleshooting....................................................................................... 6-5

iv

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

DRAWINGS (LOCATED IN REAR OF MANUAL)

620424 Schematic Diagram, Preamplier
620429 Schematic Diagram, Main Electronics
620434 Schematic Diagram, Isolated V/I
622883 Flow Diagram, Model 400A
623190 Burner Parts List
624003 Schematic Diagram, Temperature Control Board
654328 Installation Drawing, Model 400A
654905 Schematic Diagram, Relay Board
654910 Schematic Diagram, Relay Board
654913 Assembly Instructions, I/O Board
654998 Assembly Instructions, Relay Board
655354 Pictorial Wiring Diagram, Model 400A
657546 Schematic Diagram, Flame-Out Board

ONTENTS

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748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

v

ONTENTS

C

NOTES

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July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

P

REFACE

S

AFETY SUMMARY

To avoid explosion, loss of life, personal injury and damage to this equipment and
on-site property, all personnel authorized to install, operate and service the Model
400A Hydrocarbon Analyzer should be thoroughly familiar with and strictly follow the
instructions in this manual. Save these instructions.

DANGER is used to indicate the presence of a hazard which will cause severe
personal injury, death, or substantial property damage if the warning is ignored

WARNING is used to indicate the presence of a hazard which can cause severe
personal injury, death, or substantial property damage if the warning is ignored.

CAUTION is used to indicate the presence of a hazard which will or can cause minor
personal injury or property damage if the warning is ignored.

NOTE is used to indicate installation, operation, or maintenance information which is
important but not hazard-related.

WARNING: ELECTRICAL SHOCK HAZARD

Do not operate without doors and covers secure. Servicing requires access to
live parts which can cause death or serious injury. Refer servicing to qualified
personnel.

CAUTION: HIGH PRESSURE GAS CYLINDERS

For safety and proper performance this instrument must be connected to a
properly grounded three-wire source of power.

This analyzer requires periodic calibration with known zero and standard gases.
Refer to Sections 2.6, 3.8, 3.9, 3.10 and 3.11. See also General Precautions for
Handling and Storing High Pressure Cylinders, following Section 7.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

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WARNING: POSSIBLE EXPLOSION HAZARD

Do not apply power to analyzer or ignite burner until all leak checks have been
performed and until the environment of the analyzer has been determined to be
non-hazardous. See Section 2.7 for leak check procedure.

This instrument uses a fuel containment hydrogen. The instrument is designed to
protect against the formation of an explosive gas mixture within the enclosure. It
must NOT be operated if the internal ventilation fan is not functioning. Do NOT
operate without factory installed fuel flow restrictor in place.

Check the fuel supply and containment system for leaks, both inside and outside the
analyzer, upon installation, before initial startup, during routine maintenance, or any
time the integrity of the fuel containment system is broken, to assure that the system
is leak-tight. Refer to Leak Check Procedure, Section 2.7, Step 6.

The enclosure is protected by a continuous dilution air purge system, as
recommended in IEC* Publication 79-2 (Third Edition - 1983). Do not operate unit
unless the continuous dilution purge system is properly installed and
functioning. Upon startup or loss of pressurization, purge for fifteen minutes
before restoring power unless the internal atmosphere is known to be
non-explosive.

WARNING: PARTS INTEGRITY

Tampering or unauthorized substitution of components may adversely affect
safety of this product. Use only factory documented components for repair.

CAUTION: TOPPLING HAZARD

This instrument’s internal pullout chassis is equipped with a safety stop latch
located on the left side of the chassis.

When extracting the chassis, verify that the safety latch is in its proper (counter­clockwise) orientation.

If access to the rear of the chassis is required, the safety stop may be overridden by
lifting the latch; however, further extraction must be done very carefully to insure the
chassis does not fall out of its enclosure.

If the instrument is located on top of a table or bench near the edge, and the chassis
is extracted, it must be supported to prevent toppling.

Failure to observe these precautions could result in personal injury and/or damage to
the product.

P-2

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

S

PECIFICATIONS

REFACE

P

POWER REQUIREMENTS:
OPERATING TEMPERATURE:
C

ASE TEMPERATURE

:

AMBIENT HUMIDITY:

D

IMENSIONS

W

EIGHT

R

EPEATABILITY

R

ESPONSE TIME

F

ULLSCALE SENSITIVITY

S

TANDARD ANALYZER

A

NALYZER EQUIPPED WITH

H

YDROGEN FUEL ASSEMBLY

F

UEL GAS REQUIREMENTS

S

TANDARD ANALYZER

A

NALYZER EQUIPPED WITH

H

YDROGEN FUEL ASSEMBLY

S

AMPLE GAS REQUIREMENTS

B

URNER AIR REQUIREMENTS

S

AMPLE BYPASS FLOW

S

TABILITY

:

:

:

:

:

:

:

:

100%

:

100%

:

:

:

115 VAC ±10%, 50/60 ±3 Hz, 250 W
32°F to 110°F (0°C to 43°C)
Controlled at 122°F (50°C)

95% relative humidity, but not in excess of 34°C wet
bulb temperature.

8.75 in (22.2 cm) H

18.75 in. (47.6 cm) W

15.88 in. (39.7 cm) D
Recommended panel cutout is 17.75 in. X 8 25 in.

(45.1 cm x 21.0 cm).
May be mounted in standard 19 inch rack.

22 lbs (10 kg)
1% of fullscale for successive identical samples

90% of fullscale in 0.6 seconds with sample bypass
flow at 3 liters/minute

Adjustable from 4 ppm CH4 to 1% CH4. (Adjustable
from 100 ppm CH4 to 10% CH4 using high-range
capillary.)

Adjustable from 1 ppm CH4 to 0.25% CH

4

75 to 80 cc/min premixed fuel consisting of 40%
hydrogen and 60% nitrogen or helium (THC <0.5 ppm)
supplied at 45 to 50 psig (309 to 344 kPa) at
instrument

35 to 40 cc/min of clean, zero grade hydrogen (THC
<0.5 ppm) at 45 to 50 psig (309 to 344 kPa) at
instrument

Non-Flammable Samples - 0.35 to 3.0 liters/minute at
5 to 10 psig (34 to 69 kPa)

Flammable Samples - 470 cc/minute maximum for
safety1

350 to 400 cc/minute of zero grade (THC <1 ppm) air,
supplied at 25 to 50 psig (172 to 344 kPa)

0.3 to 3.0 liters/minute
Electronic stability at maximum sensitivity is 1% of

fullscale throughout ambient temperature range of
32°F to 110°F (0°C to 43°C). Built-in temperature
controller minimizes effect of ambient temperature
variations on internal flow and electronic systems.

1 Safety design basis presumes flammable sample having LEL not less than that of hydrogen (4% v/v in air).

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

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S

PECIFICATIONS (CONTINUED

R

O

S

C

T
D

R

R

:

ANGE

UTPUT

AFETY FEATURES

ONTACTS

EMPERATURE CONTROL

ATA DISPLAY

ANGE DISPLAY

EMOTE RANGE CONTROL

:

:

:

:

:

:

:

)

Eight ranges: 1, 2.5, 10, 25, 100, 250, 1000 and
REMOTE.

In addition SPAN control provides continuously variable
adjustment within a dynamic range of 4:1

1) 0 to 5 VDC, 0 to 1 VDC, 0 to 0.1 VDC fully buffered ­standard (for 0 to 100.0%).

2) 4 to 20 mA isolated voltage to current - optional
(maximum load resistance 700 ohms)

3) 0 to 5 VDC accessory output un-buffered - standard
(for 0 to 100.0%) available when current option is not
used.

Flame-on indication and automatic flame-out fuel
shutoff is standard.

All metal tubing with ferrule/nut compression fittings to
minimize potential fuel leaks.

Self-ventilated system maintains internal atmosphere
below 25% of LEL for worst case internal leakage.

Form A contact operates in parallel with flame-out fuel
shut-off solenoid contact rating (24 VDC at 1 A) for
sample shut-off by use of factory ordered kit (PN

624080) if sample is flammable (hydrogen).
Setpoint maintained at 122°F (50°C)
3-1/2 digit LED, characters 0.52 inches high, range

0000 to 1999
1 digit LED, character 0.52 inches high (1 to 7 normal

ranges, 0 to remote control)
Standard, fully isolated range control and range ID is

optional

P-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

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P

C

USTOMER SERVICE

For order administration, replacement Parts, application assistance, on-site or factory
repair, service or maintenance contract information, contact:

R

ETURNING PARTS TO THE FACTORY

Before returning parts, contact the Customer Service Center and request a Returned
Materials Authorization (RMA) number. Please have the following information when
you call: Model Number, Serial Number, and Purchase Order Number or Sales Order

Number.

Prior authorization by the factory must be obtained before returned materials will be
accepted. Unauthorized returns will be returned to the sender, freight collect.

When returning any product or component that has been exposed to a toxic, corrosive
or other hazardous material or used in such a hazardous environment, the user must
attach an appropriate Material Safety Data Sheet (M.S.D.S.) or a written certification
that the material has been decontaminated, disinfected and/or detoxified.

, T

ECHNICAL ASSIST ANCE AND FIELD SERVICE

Rosemount Analytical Inc.

Process Analytical Division

Customer Service Center

1-800-433-6076

Return to:

Rosemount Analytical Inc.

4125 East La Palma Avenue

Anaheim, California 92807-1802

T

RAINING

A comprehensive Factory Training Program of operator and service classes is
available. For a copy of the Current Operator and Service Training Schedule contact
the Technical Services Department at:

Rosemount Analytical Inc.

Phone: [phone]

FAX: [phone]

D

OCUMENTATION

The following Model 400A Hydrocarbon Analyzer instruction materials are available.
Contact Customer Service or the local representative to order.

748262 Instruction Manual (this document)

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

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REFACE

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N

OTES

P-6

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

I

NTRODUCTION

1

1.1 DESCRIPTION

The Model 400A Hydrocarbon Analyzer automatically and continuously measures the
concentration of hydrocarbons in a gas stream. Typical applications include monitoring
atmospheric air for low-level hydrocarbon contaminants and determining the
hydrocarbon content of exhaust emissions from internal combustion engines.

The analyzer utilizes the flame ionization method of detection. The sensor is a burner
in which a regulated flow of sample gas passes through a flame sustained by
regulated flows of a fuel gas and air. Within the flame, the hydrocarbon components of
the sample stream undergo a complex ionization that produces electrons and positive
ions. Polarized electrodes collect these ions, causing current to flow through an
electronic measuring circuit. The ionization current is proportional to the rate at which
carbon atoms enter the burner, and is therefore a measure of the concentration of
hydrocarbons in the original sample. The analyzer provides readout on a front-panel
digital display and a selectable output for an accessory recorder.

To ensure stable, drift-free operation, particularly in high-sensitivity applications, an
internal temperature controller maintains the analyzer interior at a constant 50°C. This
feature minimizes temperature-dependent variations in (a) electronic
current-measuring circuitry, and (b) adsorption/desorption equilibrium of background
hydrocarbons within the internal flow system.

To minimize system response time, an internal sample-bypass feature provides
high-velocity sample flow through the analyzer.

The Model 400A may be equipped with various optional features in addition to, or
instead of, the standard features of the basic instrument. The following paragraphs
provide brief descriptions of the principal standard and optional features.

1.2 ANALYZER MOUNTING OPTIONS

WARNING: INSTALLATION

For safety, the analyzer should be installed in a non-confined, ventilated space.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

1-1

NTRODUCTION

I

The standard analyzer is housed in a case designed for bench-top use, or if desired,
the analyzer may be mounted in a cabinet or rack using RETMA spaced mounting
holes. Outline dimensions are shown on DWG 654328.

1.3 FUEL GAS OPTIONS

For burner fuel gas, the standard analyzer requires 40% hydrogen/60% nitrogen or
helium. Through installation of the optional 400A hydrogen fuel kit (P/N 622576), the
analyzer may be converted to use 100% hydrogen. This kit may be ordered as a
factory installed option or supplied as an option for installation by the user.

The preferred type of fuel depends on the particular application and the characteristics
of the sample gas:

For measuring low-level hydrocarbons in ambient air, or in other sample gas with
relatively constant oxygen content, 100% hydrogen is preferable. It provides the
highest obtainable sensitivity and the maximum stability. Zero drift caused by ambient
temperature variations of the fuel cylinder is somewhat lower for 100% hydrogen than
for mixed fuel. (With either fuel, it is desirable to maintain cylinder temperature
constant.)

For monitoring vehicular exhaust emissions, or other sample gas with varying oxygen
content, mixed fuel is preferable; and a hydrogen/helium mixture is more desirable
than a hydrogen/nitrogen mixture. With this type of sample, the use of mixed fuel gas
minimizes the error introduced by oxygen synergism. An effective way to reduce the
effect of internal oxygen is to dilute it with an inert gas. This might be accomplished by
a constant dilution of sample and calibration gases ahead of the burner but it is
simpler and more accurate to provide that diluent in the form of premixed fuel. Both
nitrogen and helium have been used as a diluent, but helium has proven to be most
effective in improving the equality of response to the various species of hydrocarbons.

As indicated earlier the flame output signal is optimum when the ratio of hydrogen flow
to inert flow is about 40/60; therefore, this is the chosen composition for
hydrogen/helium premixed fuel.

The sample flow is kept low to maximize the dilution effect while still providing
adequate sensitivity. The burner air flow is normally about four times the fuel flow, and
changes have little effect on signal strength. For a given sample flow, the signal can
be optimized by adjusting the fuel flow rate.

Typical flow rates with premixed fuel:

Fuel 100 cc/min

1-2

Sample 7 cc/min
Air 400 cc/min

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

NTRODUCTION

I

It is worth noting that with a 40/60 premixed fuel, the above flows amount to 40 cc
(8%) hydrogen, 67 cc (13%) inert plus sample and 400 cc (79%) air, which compare
closely to the 30 cc (8%) hydrogen, 45 cc (12%) inert/sample and 300 cc (80%) air
given earlier for straight hydrogen fuel.

Since the sample flow in the case of mixed fuel operation is only about one-sixth of
that with straight hydrogen fuel, it is clear that higher sensitivity is obtained with
straight hydrogen fuel operation. However, in any application where the sample
contains more than one species of hydrocarbon and/or a varying concentration of
oxygen, the mixed fuel operation should be used.

The mixed fuel is recommended, not only for sample containing variable
concentrations of oxygen, but also for two specific pure gas applications. The first is
the case of pure hydrogen samples. The other is the case of pure oxygen samples. If
straight oxygen samples are used with straight hydrogen fuel, the mixture entering the
burner is essentially 40% H2/60% O2, which tends to produce an unstable signal. The
mixed fuel works better. Note that the choice of fuel determines certain analyzer
characteristics, as tabulated in Table 1-1.

1.4 OUTPUT OPTIONS

The standard analyzer provides (a) direct digital readout in percent of full scale on a
front-panel display calibrated linearly from 0 to 100 %, (b) a selectable buffered output
of 0 to 0.1 VDC, 1 VDC or 5 VDC suitable for a recorder and (c) a 0 to 5 VDC un­buttered accessory output.

An isolated output of 4 to 20 mA DC (max. load resistance 700 ohms) is obtainable
through use of the optional current output board, P/N 620433, installed either during
factory assembly or as a subsequent addition. When installed, this board uses the
accessory 0 to 5 VDC output as an input signal and replaces this function at the
output terminals.

ANALYZER

CHARACTERISTICS

Fullscale Sensitivity

Adjustable from 1 ppm CH4
to 2% CH4

100% H2

Fuel Consumption 35 to 40 cc/min 75 to 80 cc/min
Operating Range for

SAMPLE Pressure

4 to 5 psig (27 to 34.5 kPa)

Regulator

40% H2/60% N2 or

40% H2/He

Adjustable from 4
ppm CH4 to 10%
CH4

1.5 to 5 psig
(10.3 to 34.5 kPa)

T

ABLE

748262-K Rosemount Analytical July 1997

1-1. F

UEL GAS VS

. A

NALYZER CHARACTERISTICS

Model 400A Hydrocarbon Analyzer

1-3

NTRODUCTION

I

1.4.1 I

1.4.2 R

SOLATED REMOTE RANGE CHANGE AND IDENTIFICATION

This option provides a 24 VDC operation of remote range and identification as well as
providing terminals for flame out indication.

ANGE TRIM OPTION

This option provides individual potentiometers for each range to allow adjustment of
individual differences in bottled gas.

1.5 SAMPLE PUMP OPTION

To provide the required sample flow, the sample gas must be under adequate
pressure when applied to the analyzer inlet. Refer to Paragraph 2.4. To permit
analysis of gases at atmospheric or sub-atmospheric pressure, the analyzer may be
shipped with a sample pump accessory, P/N 621062.

1.6 GAS SAFETY FEATURES

The Model 400A is designed to provide a high degree of operational safety. In all
analyzers, a front-panel LED indicates that the burner flame is lit. In addition, fuel gas
is automatically shut off when a flame-out condition occurs.

All tubing ahead of the burner is rigid metallic tubing made up with ferrule/nut type
compression fittings. However, should there be an internal fuel leak, an inlet fuel flow
limiting restrictor, ventilation holes in the enclosure and an internal circulation fan
serve to dilute and dissipate the hydrogen fuel for a worst case leak to a safety factor
below 25% of the LEL of hydrogen. The design basis for this system presumes 100%
hydrogen fuel at 50 psig inlet pressure. 40% hydrogen fuel and lower inlet pressure
serve to further reduce hydrogen concentration in the event of a leak. In reality, an
open fitting leak would never occur. As a leak developed the burner would eventually
be starved of fuel and flame-out would occur at a leak equivalent of a loss of about 20
psig fuel pressure, thus actuating the fuel shut-off solenoid valve system.

1-4

If the sample is flammable, accessory kit P/N 624080, must be utilized. This kit
provides a restrictor to limit sample flow and a solenoid valve to shut-off sample in the
event of burner flame-out. The design basis for this kit presumes a maximum sample
flow rate of 470 cc/min and a sample with LEL not below that of hydrogen (4% v/v in
air).

WARNING: POSSIBLE EXPLOSION HAZARD

Protection against explosion depends upon special fuel flow limiting restrictor
in fuel inlet fitting. Do not remove fuel inlet restrictor. Replace only with factory
supplied fitting.

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer