Emerson Rosemount Analytical 400A Instruction Manual

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

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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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P

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.

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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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P

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

REFACE

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

P-5

REFACE

P

N

OTES

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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
Sample 7 cc/min
Air 400 cc/min

1-2

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

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.

1.4.2 R

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.

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.

1-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

I

NSTALLATION

2

2.1 UNPACKING

Carefully examine the shipping carton and contents for signs of damage. Immediately
notify the shipping carrier if the carton or its contents are damaged. Retain the carton
and packing materials until the instrument is operational.

2.2 LOCATION

Install analyzer in a clean area, not subject to excessive vibration or extreme
temperature variations. Preferably, the analyzer should be mounted near the sample
stream, to minimize sample-transport time.

WARNING: INSTALLATION RESTRICTIONS

For safety, the analyzer should be installed in a non-confined, ventilated space.
Do not block any of the vent holes at the top of each side panel of the
instrument as they are part of the safety system.

A thermostatically controlled heating circuit holds internal temperature of the analyzer
to the correct operating temperature for ambient temperatures in the range 32°F to
110°F (0°C to 43°C).

The cylinders of fuel, air, and calibration gas(es) should be located in an area of
relatively constant ambient temperature.

2.3 VOLTAGE REQUIREMENTS

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.

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

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

2-1

NSTALLATION

I

This instrument was shipped from the factory configured to operate on 115 VAC,
50/60 Hz electric power. Verify that the power source conforms to the requirements of
the individual instrument, as noted on the name-rating plate.

Note:
230 VAC operation requires an accessory transformer mounted external to the

instrument. If external 230 VAC power is provided, do not change the switch
setting on the Temperature Control Board, which is factory-selected for 115
VAC. A 230 VAC switch setting will cause the case temperature controller to
malfunction.

2.4 FUEL AND AIR REQUIREMENTS

WARNING: INSTALLATION RESTRICTIONS

Fuel, air and calibration gas cylinders are under pressure. Mishandling of gas
cylinders could result in death, injury or property damage. Handle and store
cylinders with extreme caution and in accordance with manufacturer's
instructions. Refer to General Precautions for Handling and Storing Gas
Cylinders, which follows Section 7 of this manual.

During normal operation, the analyzer uses fuel and air to maintain the burner flame.
Criteria for selection of these gases are given in Sections 2.4.1 and 2.4.2. In addition,
the analyzer requires suitable standard gas(es) for calibration. Refer to Section 3.1.1.

Each gas used should be supplied from a tank or cylinder equipped with a clean,
hydrocarbon-free, two-stage regulator. In addition, a shutoff valve is desirable. Install
the gas cylinders in an area of relatively constant ambient temperature.

2.4.1 F

UEL GAS

The standard analyzer is equipped to use only mixed fuel, i.e. 40% hydrogen/60%
nitrogen or helium. Such blends are supplied by many gas vendors specifically for this
use, with a guaranteed maximum total hydrocarbon content of 0.5 ppm, measured as
methane (THC < 0.5 ppm). This specification should be used when buying such
mixtures.

When the analyzer is equipped with the optional hydrogen fuel kit, P/N 622576, 100%
hydrogen fuel is to be used. This is also supplied by many gas vendors specifically for
this use, with the same guaranteed total hydrocarbon content (THC < 0.5 ppm) which,
again, should be specified when buying the gas.

Note:
Always assure the sample flow is present when using the 100% hydrogen fuel

option. Absence of sample flow can result in burning of detector tip when using
100% hydrogen.

2-2

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

NSTALLATION

I

2.4.2 A

IR

Burner air should also be relatively free of hydrocarbons in order to assure a low
background signal. Several grades of air are supplied by various gas vendors for this
use. A maximum total hydrocarbon content of less than 1 ppm (THC < used as a zero
standard).

An alternate source of pure air for burner and zero gas can be provided by a
diaphragm pump and heated palladium catalyst which effectively removes moderate
amounts of both hydrocarbons and carbon monoxide from normal ambient air on a
continuous basis.

2.5 SAMPLE HANDLING

CAUTION: BYPASS GAUGE PROTECTION

When applying sample pressures greater than 5 psig, insure that the bypass
regulator is fully open to protect the bypass gauge.

Operating range for the internal sample pressure regulator is 4 to 5 psig (28 to 35 kPa)
for an analyzer using 100% hydrogen fuel, and 1.5 to 5 psig (10 to 35 kPa) for an
analyzer using mixed fuel. With either fuel, sample and calibration gas(es) must be
supplied to the sample inlet at a pressure slightly, but not excessively higher than the
desired setting on the internal sample pressure regulator. The criterion for correct
supply pressure is that the gas flow discharged from the by-pass outlet must be
between 0.5 and 3.0 liters/minute to operate within the control range of the sample
pressure regulator, and preferably should be between 2 and 3 liters/minute to
minimize system response time.

Note that use of excessive bypass flow will not only cause the sample pressure
regulator to operate outside its control range, but will also result in rapid depletion of
sample and standard gases.

If the analyzer is equipped with the accessory 400A sample pump, P/N 621062, the
acceptable pressure range at the pump inlet is approximately -1 to +2.5 psig (7 to 17
kPa). If the pump is used , it will automatically provide a sam ple bypass flow within the
correct range. If the analyzer is not equipped with sample pump, adjustment of the
bypass flow is obtainable by inserting an external flow controller or throttle valve into
the external sample line, upstream from the sample inlet. Flow may be measured by
connecting a flowmeter to the by-pass outlet.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

2-3

NSTALLATION

I

WARNING: POSSIBLE EXPLOSION HAZARD

In the event that flammable sample is to be introduced into this analyzer, it must
be equipped with accessory kit PN 624080, which restricts sample flow and
provides automatic sample shutoff in the event of burner flameout. DO NOT
OPERATE WITHOUT SAMPLE FLOW RESTRICTOR IN PLACE. The sample
containment system should also be thoroughly leak checked. This kit is
designed considering application on hydrogen sample (LEL=4% v/v). The
instrument must not be used on a sample having a LEL less than 4% in air.

2.6 GAS CONNECTION

For external gas lines, the use of all new tubing throughout is strongly recommended.
Copper refrigeration tubing is preferred. Stainless steel tubing is less desirable,
because it contains hydrocarbon contaminants, necessitating thorough cleaning
before installation.

In connecting gas supply lines and associated fittings, use Teflon tape only. Do not
use pipe thread compound or other substance with an organic base.

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 analyzer has been designed for use in environments that do not contain
combustible or explosive materials.

This analyzer uses a fuel containing hydrogen. Leakage from the fuel containment
system can result in an explosion. The fuel supply and containment system, both
inside and outside the analyzer, should be carefully checked for leaks upon
installation, before initial startup, during routine maintenance or any time the integrity
of the sample containment system is broken.

If hazardous sample is to be introduced into this analyzer, the leak check
procedure should also be applied to the sample containment system, both
inside and outside the analyzer.

Proceed as follows:

1. Check analyzer to make sure that plugs and caps are removed from all inlet and

outlet fittings.

2-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

NSTALLATION

I

2. If a vent line is to be connected to exhaust outlet, use 1/2-inch ID tube slanted
downward at least 10 degrees from horizontal.

Note:
Since water vapor is formed during oxidation of hydrogen, burner exhaust gas

always contains moisture, even if air and fuel entering the burner are completely
dry. Unless exhaust line slants down, water may accumulate in line, causing
back pressure and noisy readings. If exhaust line becomes blocked, water may
back up in line and flood burner.

3. If sample is toxic or noxious, or is to be reclaimed, connect by-pass outlet to
suitable disposal system. Do not use any device causing back pressure on burner.

4. Clean external fuel, air, and sample lines and regulators. If necessary, heat lines
with torch to drive out contaminants.

CAUTION: DISCONNECT ALL LINES

Do not perform this operation with the fuel, air and sample lines connected to
the analyzer

5. Recommended method is to attach the tubing to either a nitrogen or helium
cylinder through a two-stage regulator, and adjust the regulator for a low flow of
gas through the tubing. Use a propane or natural gas torch to heat the tubing to at
least 300oC, working the heat source slowly from the regulator end to the open
end. This will remove contaminants from the inside walls of the tubing, and drive
them out the open end.

6. Connect external fuel and air lines to fuel and air inlet fittings on analyzer. Connect
external sample line to sample inlet on analyzer (or to inlet fitting on sample pump,
if used).

7. Adjust regulators on fuel and air cylinders (or other gas supply sources) for
appropriate output pressure. Maximum permissible pressure at AIR and FUEL
inlets of analyzer is 50 psig (345 kPa). The pressure at the AIR inlet must be at
least 5 psig (35 kPa) higher than the desired setting on the air pressure gauge
within the analyzer. Thus if the internal FUEL pressure regulators are to be set at a
typical value of 25 psig (172 kPa), the pressure at the FUEL inlet must be set 15 to
20 pounds higher than the operating pressure.

8. Supply sample gas at appropriate pressure, as explained in Section 2.5. Sample
bypass flow must be between 0.5 and 3.0 liters/minute for proper operation.
Preferably, it should be between 2.0 and 3.0 liters/minute, to minimize system
response time. Flow may be measured by connecting a flowmeter to BY-PASS
outlet.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

2-5

NSTALLATION

I

2.7 LEAK CHECK

WARNING: POSSIBLE EXPLOSION HAZARD

Be particularly careful in checking for leaks in the fuel lines. Fuel gas leakage
can cause an explosion.

Check all gas connections to ensure that they are leak free. Use of SNOOP (P/N

837801) or other suitable leak-test liquid is recommended. Do not use soap or other
organic substances; they will contaminate the system, resulting in e xcessive noise an d
background current. To leak check the fuel containment system, it is necessary to
have full operating pressure within the system. To accomplish this, hold the
momentary IGNITE/PURGE switch in the up or PURGE position.

2.8 ELECTRICAL CONNECTIONS

WARNING: POSSIBLE EXPLOSION HAZARD

Before supplying electrical power to analyzer, complete the gas connections
and verify that fuel gas connections are leak free. Refer to Section 2.7.

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.

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

2.8.1 L

INE POWER CONNECTION

The Model 400A is manufactured to operate only on 115 VAC power. (Note that the
power input box and power selection card display only 115 VAC operation.)

The power cable supplied is provided with a North American-style parallel blade
grounded plug which must be inserted into a 3-wire grounded receptacle.

If 230 VAC operation is desired, an external isolated step-down transformer accessory
(not supplied) is required.

2-6

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

NSTALLATION

I

2.8.2 V

OLTAGE OUTPUT SELECTION AND CABLE CONNECTIONS FOR RECORDER

The standard analyzer provides voltage output only. As shipped from the factory, the
analyzer is set up for use with a 100 mV recorder (program header connecting pins E9
and E10).

A selection of three voltage output ranges, 0 to 0.1 VDC, 0 to 1.0 VDC or 0 to 5.0 VDC
are available at terminals 3 and 4 of the lower six-position barrier strip labeled
OUTPUT. Refer to Figure 2-1. To select 0 to 1.0 VDC range, connect pins E7 and E8
on the main electronics board assembly, P/N 620428, with the program header. For
the 0 to 5.0 VDC range, connect pins E5 and E6, and for the 0 to 0.1 VDC range,
connect pins E9 and E10, with the program header. This is a fully buffered signal and
can be used with most types of voltage recorders. A 10 VDC output displays 1999 on
digital readout, indicating 99.9% overrange. A 5 VDC output displays 1000 on digital
readout and indicates 100%, the normal instrument span.

2.8.3 V

OLTAGE TO CURRENT OUTPUT BOARD (OPTIONAL

)

The optional current output in the range of 4 to 20 mADC appears at terminals 5 and

6. Refer to Figure 2-1. This current may be transformed back to a voltage using the

appropriate resistor. This fully isolated current board is an instrument option and
mounts internally on the Model 400A front panel assembly. The maximum value of
load resistor is 700 ohms. The 4 to 20 mA is valid over the range of 0 to 100%; the
overrange capability of 99.9% is not usable with this option because maximum output
of 20 mA corresponds to 5 VDC out.

If the voltage to current option is not utilized, insert program header connecting pins
E1/E2 and E3/E4 on the main electronics board assembly to allow a voltage to appear
at terminals 5 and 6 in place of the current.

2.8.4 A

UXILIARY CONTACTS

A Form A contact closure is available on pins 1 and 2 of the lower barrier strip at the
rear of instrument. Refer to Figure 2-1. These contacts may be used with an existing
alarm panel or annunciator system, providing the current and voltage limits are
observed. The rating for the contacts is 24 V at 1A DC. Contacts operate in parallel
with the internal fuel shutoff solenoid and may therefore be used for external "flame
out" indication.

2.8.5 R

EMOTE RANGE CONTROL AND INDICATION

The Model 400A allows remote control of range or alternatively remote control
indication; this is standard with each unit. As an option, a fully isolated interface may
be installed. It performs the same function but assures electrical isolation between the
analyzer and the control or indication module. The isolated range/indication option
requires an external 24 VDC power supply for operation.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

2-7

NSTALLATION

(+)

)

I

ANGE CONTROL (NON-ISOLATED

R

)

Terminals 1 through 7 on the upper terminal block at the rear of the instrument are
used for this function. Select RMT on the front panel RANGE switch. Connect the
respective line, 1 through 7, to pin 3 (labeled GND) on the lower barrier strip. The front
panel will indicate the range selected. Terminals 1 through 7 correspond to ranges 1
through 7. Table 2-1 shows a simple range selection arrangement.

ANGE INDICATION (NON-ISOLATED

R

)

When the RANGE switch is in any position, including RMT, the range selection of the
instrument may be determined by sensing an output in terminals 1 through 8 on the
upper terminal strip at the rear of the instrument. Any selected range, 1 through 7 or
RMT (position 8), will be indicated as a low or ground signal with respect to pin 3 of
the lower barrier strip labeled GND; all un-selected ranges will indicate a high or +5
VDC with respect to this same terminal.

F

IGURE

2-1. R

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 REM 24V 24V

J8

CNT1 CNT2 SND OUT

RANGE CONTROL

24VDC MAX

1 AMP

1 2 3 4 5 6

OUTPUT

ANGE INPUT-OUTPUT BOARD

LOWER TB UPPER TB

Terminal 3

1234567
Range 1 X X
Range 2 X X
Range 3 X X
Range 4 X X

RANGE RET

VI

(-

Range 5 X X
Range 6 X X

Range 7

T

ABLE

2-1. R

ANGE CONTROL

2-8

XX

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

NSTALLATION

I

SOLATED REMOTE RANGE CONTROL AND IDENTIFICATION

I

The Remote Control Assembly is located on the rear panel of the instrument and is
shown in Figure 2-2. Connections should be made to the terminals marked Range
Control where a single line interference is desired. By removing steering diodes on
printed circuit board 654910, individual Range Control and Range I/O connections
may be made. Connections are made to bare wire terminal which are easily
removable to facilitate in stallation.

Wires should not be tinned prior to installation to prevent premature loosening.

Note:
The terminal strips on the module use screws to secure bare wires. These wires

should not be tinned or they may loosen prematurely.

Range changes are achieved by applying 24VDC at about 150 mW to the terminals
marked "range control," using the common terminal as return. Only one range may be
selected at once. Range indication is achieved by individual 24 VDC (1 A) relay
contacts.

WARNING: ELECTRICAL HAZARD

Range indication relay contacts are limited to 24 VDC. Use of 115 VAC is
unsafe.

Common control/sense connections may be made to the range control terminals.
Voltage and current output signals are also available on the range change module.

Voltage output must be used with a load of greater than 10 kilohms, current output
with less than 600 ohms. Voltage output interconnects should be shielded (use the V­output for shield connection) but current output shielding is less critical. If used,
current output shielding should be grounded on the reception end (computer or chart
recorder).

EMOTE FLAME OUT INDICATION

R

Terminals for flame out indication (TS12) are shown in Figure 2-2.

2.8.6 S

AMPLE PUMP ACCESSORY

If a sample pump is used, 115 VAC, 50/60 Hz power must be provided to the pump
accessory independently. A power cord is provided with this option and mates with a
standard 3-pin power connector at the rear of the housing.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

2-9

NSTALLATION

I

F

IGURE

OUTPUT

V mA

+ - + - C NO

REMOTE

2-2. R

ANGE CONTROL AND OUTPUT CONNECTIONS

24V ID

C 7 6 5 4 3 2 1

C 7 6 5 4 3 2 1

FLAME OUT
24VDC MAX

TS12

CONTROL LINES 24 VDC, 150 Mw
ALL CONTACTS 24 VDC MAX, 1 A MAX
CURRENT OUTPUT 600 OHMS MAX

TS10 RANGE ID 24 VDC MAX

TS11 RANGE CONTROL 24 VDC

SINGLE LINE CONTROL/SENSE
USE "RANGE CONTROL" CONNECTIONS

2-10

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

S

TARTUP AND CALIBRATION

3

3.1 INITIAL STARTUP AND CALIBRATION

Section 3.1.1 discusses calibration methods and the associated standard gases.
Section 3.2 explains the typical calibration procedure.

After installing analyzer per Section Two, proceed as follows:

1. Set the RANGE multiplier switch (located inside the small door on the analyzer
front panel) at 1000. Place POWER switch (located in the upper right-hand corner
of the main electronics board on the back of the front panel) at ON. See Figure
3-1. The display should light up.

2. Set external regulators on air and fuel cylinders (or other gas supply sources) for
suitable output pressure. Maximum permissible pressure at AIR and FUEL inlets of
analyzer is 50 psig (345 kPa). The pressure at the AIR inlet must be at least 5 psig
(25 kPa) higher than the desired setting on the air pressure gauge within the
analyzer. The internal FUEL pressure regulator is to be set at a typical value of 25
psig (172 kPa), the pressure at the FUEL inlet must be set at least 20 lbs. higher
than the operation pressure.

3. If analyzer uses 100% hydrogen fuel, supply actual sample or other suitable gas to
SAMPLE inlet port of analyzer (or to inlet fitting on sample pump, if provided). Note
pressure and flow requirements explained in Section 2.4.

CAUTION: POSS IBLE BURNER DAMAGE

If analyzer uses 100% hydrogen fuel, an adequate flow of sample or other gas
must enter sample inlet at all times when flame is burning. Otherwise, burner
will overheat and damage burner tip.

If analyzer uses mixed fuel, sample flow may be initiated at this time, although it is not

necessary.

4. Set internal pressure regulators at values appropriate to the fuel gas used. Refer to
Table 3-1.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

3-1

TARTUP AND CALIBRAT ION

S

Internal

Pressure

Regulator

100% H2 Fuel Mixed Fuel

psig/kPa psig//kPa

Fuel Gas

Air 5/35 5/35
Fuel 25/175 30/207
Sample 5/35 0/0

T

ABLE

3-1. I

The PURGE/IGNITE switch has two positions, IGNITE and PURGE.

NTERNAL PRESSURE REGULATORS SETTINGS

5. With PURGE/IGNITE switch in PURGE position, wait about one minute for fuel gas
to purge flow system. During purging period, rotate FUEL pressure regulator
alternately clockwise and counterclockwise several times, then return to setting
specified in Step 4.

6. Briefly hold (2 to 4 sec.) PURGE/IGNITE switch in IGNITE position, then release.
FLAME indicator should now be ON, indicating that flame is burning. If so,
proceed with following steps. If FLAME indicator does not stay on, the flame is not
burning. Again actuate IGNITE switch If flame does not ignite after several
attempts, refer to troubleshooting chart, Table 6-1. If difficulty is experienced,
allowing gas to flow for 20 or 30 seconds in the PURGE position prior to actuating
the IGNITE switch may be helpful.

F

IGURE

3-1. P

OWER SWITCH LOCATION

3-2

POWER

OFF ON

S2

Front Panel

Power Switch S2

Main Electronics Board

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

TARTUP AND CALIBRATION

S

Note:
If ignition indication [FLAME ON] is observed without obtaining proper

sensitivity, refer to Table 6-1, Item 6.

Note:
When lighting the burner after extended shutdown, the instrument will require

time to allow fuel to reach the burner. Therefore, extended operation of the
switch may be required.

7. Increase setting on internal AIR pressure regulator to at least 15 psig (103 kPa).
Recommended operating settings for internal pressure regulators are AIR, 15 psig
(103 kPa); FUEL, 25 psig (172 kPa). Verify that FLAME indicator is still on.

The analyzer is equipped with an automatic fuel shutoff solenoid. If flame goes out

during subsequent operation, fuel gas flow will shut off automatically.

If analyzer has been in regular use, it is now ready for calibration, per Section 3.2.1,

and then for normal operation. However, during initial startup, or startup following a
prolonged shutdown, the following steps should first be performed.

8. Check for contamination in air and fuel systems:

a. Supply a clean, hydrocarbon-free gas, such as pure nitrogen to the SAMPLE

inlet. Adjust external flow controller or throttle valve so that flow discharged
from BY-PASS outlet is between 0.5 and 3.0 liters/minute (preferably between

2.0 and 3.0 liters/minute). Set internal SAMPLE pressure regulator at 5.0 psig
(34.5 kPa).

b. Set RANGE switch at 10, SPAN control at 1000 (maximum sensitivity), and

ZERO control at 1000 (minimum zero suppression). Approximate fullscale
sensitivity is now 10 ppm as methane for mixed fuels if the analyzer uses
100% hydrogen fuel, and 40 ppm methane if the analyzer uses mixed fuel.

c. Check display. Maximum acceptable reading is 50% of fullscale. A higher

reading indicates that the contamination level is undesirably high. Excessive
noise and baseline drift may result, depending on the desired operating range.
If the instrument is to be operated at high sensitivity, the source of the
contamination must be determined and the condition corrected. The most
probable contamination sources are the fuel and air supplies, external
regulators and connecting lines, and the internal flow system of the analyzer.

If the instrument is to be operated at a sensitivity low enough so that the noise
and drift will not be observable on the display or recorder, removal of the
source of contamination is unnecessary.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

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TARTUP AND CALIBRAT ION

S

9. W ith flam e burning, allow system to stabilize for at least two hours, and preferably
for a day. After initial startup, or after startup following a prolonged shutdown, the
analyzer may display baseline drift for a considerable period of time, particularly on
the more-sensitive ranges. Commonly, small amounts of hydrocarbons are present
on the inner walls of the tubing in both the internal flow system and the external
gas-supply system. Drift results from any factor influencing the equilibrium of these
absorbed hydrocarbons. Typical causes are change of fuel cylinders or change in
temperature or pressure. (Note that this type of drift occurs only when the flame is
burning. If drift occurs when the flame is extinguished, the electronic circuitry is at
fault.)

To minimize drift, use clean fuel and air, keep the analyzer clean, and locate the gas
cylinders in an area of relatively constant ambient temperature.

3.1.1 S

ELECTION OF CALIBRATION METHOD AND ASSOCIATED STANDA RD GAS(ES

Preparatory to normal operation of the analyzer, it is necessary to select a suitable
calibration method and appropriate standard gas(es). Proper choice depends on the
type of fuel gas, the intended operating range, and the desired accuracy. In all
methods, the objective is to establish both a downscale point and an upscale point on
the display or recorder chart. Different methods are described below.

OWNSCALE CALIBRATION POINT

D

The downscale calibration point is set with the ZERO control, by the appropriate one
of two methods:

1. The generally preferred method is to adjust the ZERO control while a zero
standard gas of low, accurately-known, hydrocarbon content is entering the
SAMPLE inlet port. This method is desirable with all analyzers, and is mandatory if
the analyzer utilizes 100% hydrogen fuel. Typically, nitrogen (zero gas grade) is
used as the zero gas. If desired, the burner air may be used as zero gas, provided
that its hydrocarbon content is sufficiently low and accurately known. Although
ideally the zero gas should be completely hydrocarbon-free, even the most
carefully prepared bottled gas contains trace hydrocarbons. If the analyzer is to be
used at high sensitivity, request that the supplier of the zero gas provide an exact
determination of its hydrocarbon content.

)

2. If the analyzer utilizes mixed fuel, an alternative method eliminates the requirement
for a special zero gas. Instead, the ZERO control is adjusted with no gas entering
the SAMPLE inlet. This method is not possible with analyzer utilizing 100%
hydrogen fuel, because the burner would overheat. Even with mixed fuel, the
method is not recommended if the analyzer is to be used at sensitivity less than
100 ppm full scale.

3. Refer to Figure 3-2 for typical curves of downscale response versus time for
various hydrocarbons.

3-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

TARTUP AND CALIBRATION

S

Sample CH4 (Methane)

Sample C3H8 (Propane)

Analyzer
Response

Time

Sample C6H

(Hexane)

14

F

IGURE

3-2. T

PSCALE CALIBRATION POINT

U

YPICAL CURVES OF DOWNSCALE RESPONSE VS

H

YDROCARBONS

. T

IME FOR VARIOUS

In all applications, the upscale calibration point is established by adjustment of the
SPAN control, while a standard gas of accurately known hydrocarbon content is
flowing into the SAMPLE inlet port. Since instrument response is linear, it is not
necessary that the hydrocarbon content of the span gas fall within the desired
operating range. The instrument may be standardized on one range, and then
switched to another range without loss of accuracy. Commonly, a conveniently
obtained standard such as 100 ppm methane or 1000 ppm methane is used
regardless of range.

A span gas consists of a specified concentration of methane or other hydrocarbon in a
background gas such as nitrogen. Instrument response is affected by the composition
of the background gas. Therefore, it is desirable that the span gas contain the same
background gas as the actual sample. If so, the background effect is automatically
canceled out.

TANDA RD GAS(ES

S

)

Upscale standard gas (and zero standard gas, if used) should be supplied from a tank
or cylinder equipped with a clean, hydrocarbon-free, two-stage pressure regulator.

3.2 CALIBRATION PROCEDURE

After completing startup procedure of Section 3.1.1, calibrate analyzer as explained
below.

1. Set downscale calibration point as follows:

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

3-5

TARTUP AND CALIBRAT ION

S

a. Supply zero gas to SAMPLE inlet. Adjust external flow controller or throttle

valve so that flow discharge from BY-PASS outlet is between 0.5 and 3.0
liters/minute (preferably between 2.0 and 3.0 liters/minute). Set internal
SAMPLE pressure regulator at 5 psig (34 kPa) or other desired value.
(Recommended operating range is 4 to 5 psig [28.6 to 34 kPa] for analyzer
using 100% hydrogen fuel, and 1.5 to 5 psig [10 to 34 kPa] for analyzer using
mixed fuel.)

CAUTION: POSS IBLE BURNER DAMAGE

If analyzer uses 100% hydrogen fuel, an adequate flow of sample or other gas
must enter sample inlet at all times when flame is burning. Otherwise, burner
will overheat and damage burner tip.

b. Set RANGE switch at 10 and SPAN potentiometer at 1000. The resultant

approximate fullscale sensitivity is 10 ppm methane for an analyzer using
100% hydrogen fuel, and 40 ppm methane for an analyzer using mixed fuel.

c. Adjust ZERO control for reading of zero (or appropriate near-zero value) on

indicator or recorder. The resultant setting on the ZERO control is
approximately correct, and is sufficiently accurate for most applications.
However, if instrument is to be used for high sensitivity analysis, a recheck
and possible slight readjustment will be made. Refer to Section 4.4.

2. Set upscale calibration point as follows:
a. Turn RANGE switch to setting appropriate to the particular span gas. Refer to

Table 3-2.

b. Supply span gas to SAMPLE inlet. Adjust external flow controller or throttle

valve so that flow discharged from BY-PASS outlet is between 0.5 and 3.0
liters/minute (preferably between 2.0 and 3.0 liters/minute). Verify that
reading on internal SAMPLE pressure gauge is 5 psig or other desired value;
if not, adjust SAMPLE pressure regulator as required.

c. Adjust SPAN control so that the display or recorder gives the desired

indication. Lock SPAN control by pushing lever down.

Analyzer calibration is now sufficiently accurate for most applications. However, if

instrument is to be used for high sensitivity analysis, recheck zero setting
(refer to Section 4.4). If recorder readout and display do not agree, correct
display by adjusting R1 on front panel board.

d. Supply zero gas to SAMPLE inlet as in Step 1a. Set RANGE switch at 10.

Note reading on indicator or recorder; if incorrect, adjust ZERO control as
required. Lock ZERO control by pushing lever down. Analyzer is now ready
for routine operation as explained in Section 4.

3-6

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

TARTUP AND CALIBRATION

S

RANGE SWITCH

SETTINGS

APPROXIMATE OPERATING RANGE SPAN

CONTROL AT 1000

1 0 to 1 ppm CH4 0 to 4 ppm CH4

2.5 0 to 2.5 ppm CH4 0 to 10 ppm CH4
10 0 to 10 ppm CH4 0 to 40 ppm CH4
25 0 to 25 ppm CH4 0 to 100 ppm CH4
100 0 to 100 ppm CH4 0 to 400 ppm CH4
250 0 to 250 ppm CH4 0 to 1000 ppm CH4
1000 0 to 1000 ppm CH4 0 to 4000 ppm CH4

Note: For best results, calibrate with appropriate span gas every time the range is changed.

For a clear understanding of the function of the Range Switch, see Section 3.3.

T

ABLE

3-2. R

ANGE SWITCH SETTINGS

3.3 RANGE SWITCH

The operator can choose from seven range multipliers as represented by the settings
on the Range Switch: 1, 2.5, 10, 25, 100, 250, and 1000.

Range 1 is the most sensitive, range 1000 the least sensitive. Range 1 is 10 times
more sensitive than Range 10 and so forth.

The Range Switch settings (multipliers) and the display outputs do not represent
hydrocarbon concentrations in percent or ppm. The LED display shows the percent of
the fullscale range which has been calibrated on the multiplier selected. The display
also shows which range multiplier has been selected on the Range Switch (1 = 1, 2 =

2.5, 3 = 10, 4 = 25, 5 = 100, etc.).
Range 1 has a maximum sensitivity of 1 ppm CH4 (as 100% fullscale) if 100% H2 fuel

is used, or 4 ppm CH4 if mixed fuel is used. Range 2.5 has a maximum sensitivity of

2.5 ppm CH4 with 100% H2, 10.0 ppm CH4 with mixed fuel.

XAMPLE

E

With the Range Switch set at 2.5, the
operator can use, for example, 6 ppm
CH4 span gas to calibrate the
instrument for 20 ppm fullscale (30.0%

1:

30.0 2

PERCENT OF RANGE RANGE

x 20 ppm CH4 = 6.0 ppm). See Figure
3-3 for display output and Range
Switch setting.

RANGE MULTIPLIER

100

25

10

2.5

1

250

1000

RMT

748262-K Rosemount Analytical July 1997

F

IGURE

3-3. E

Model 400A Hydrocarbon Analyzer

XAMPLE

1 D

ISPLAY

3-7

TARTUP AND CALIBRAT ION

S

XAMPLE

E

2:

After the calibration in Example 1,
Range 10 is now automatically
calibrated for 80 ppm CH4 as 100%
fullscale. (Note that Range 10 is 4
times less sensitive than Range 2.5).
Therefore, when the operator switches
from Range 2.5 to Range 10, the
display will show 7.5% fullscale fo r pp m
CH4 calibration gas since 7.5% x 80
ppm CH4 = 6.0 ppm CH4. See Figure
3-4.

75.0 1

10

2.5

XAMPLE

E

3:

F

IGURE

3-4. E

XAMPLE

2 D

ISPLAY

Likewise, after the calibration in
Example 1, Range 1 is automatically

7.5 3

calibrated for 8 ppm as 100% fullscale.
Therefore, when switching from Range

2.5 to 1 (which is 2.5 times more
sensitive than 2.5), the display will
show 75.0% fullscale for 6.0 ppm CH
calibration gas (because 75.0% x 8
ppm CH4 = 6 ppm CH4). See Figure

4

10

2.5

3-5.

F

IGURE

3-5. E

XAMPLE

3 D

ISPLAY

Note:
The precision of the analyzer is

±±±±

1% fullscale of range. Analyzer should be
calibrated with a span gas that has a hydrocarbon concentration as close to the
fullscale concentration as possible.

3.4 RANGE TRIM OPTION

The Range Trim option allows the user to adjust each range separately to compensate
for differences between calibration gas cylinders from range to range.

See Figure 3-6. The E1, E2 and E3 jumpers allow selection from "fixed" front span
potentiometer use to "trim" individual potentiometers for each range. In the trim
position, the adjustment range of the individual pot is about 20% when the front panel
span pot is set fully clockwise. If the front panel span pot is set fully counterclockwise,
the individual pot range is about 5%.

3-8

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

SPAN

-5V REF
ZERO

AGND

DGND

TP9

TARTUP AND CALIBRATION

S

FIXED

R10 5K

J11

3

+5V

R38
30K

R9
20K

C1
1uF

2

1

6

5

4

16

9

CR1

E1
E2

R1

E3

TRIM

K1

2

10K

R2

10K

R3

10K

R4

10K

R5

10K

R6

10K

R7

10K

2

CR2 CR6

CR3

K1

6,7

12

K2

6,7

12

K3

6,7

12

K4

6,7

12

K5

6,7

12

K6

6,7

12

K7

6,7

12

K3

2

CR4

K4K2

2

CR5

J11

15
14
13
12

8

K5

2

K6

2

CR7

K7

2

7
10
11

F

IGURE

3-6. R

11

11

11

11

11

ANGE TRIM OPTION SCHEMATIC

11

11

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

3-9

TARTUP AND CALIBRAT ION

S

N

OTES

3-10

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

O

PERATION

4

4.1 ROUTINE OPERATION

After calibrating instrument per Paragraph 3.2, proceed as follows:
Supply sample gas to SAMPLE inlet. Adjust external flow controller or throttle valve so

that flow discharged from BY-PASS outlet is between 0.5 and 3.0 liters/minute
(preferably between 2.0 and 3.0 liters/minute). Note reading on BY-PASS pressure
gauge. It should be the same as that used during adjustment of the SPAN control; if
not, adjust SAMPLE pressure regulator as required.

Turn RANGE switch to appropriate position. Indicator (and recorder, if used) will now
automatically and continuously indicate the hydrocarbon content of the sample.
Normally, readout is in terms of CH4, since this is the particular hydrocarbon present in
the usual span gas. Note that readings obtained during operation depend on the type,
as well as the concentration, of hydrocarbons in the sample.

If maximum accuracy and stability are desired, observe the operating requirements
explained in Section 4.4.

4.2 RECOMMENDED CALIBRATION FREQUENCY

After initial startup, or startup following a prolonged shutdown, the analyzer requires
about one day for stabilization. For the first few days thereafter, calibrate daily.
Subsequently, the frequency of calibration can be reduced as experience dictates,
consistent with the accuracy requirements of the particular application.

4.3 SHUTDOWN

WARNING: SHUTDOWN PROCEDURE

For safety in shutdown, always turn off fuel gas first, then the air and sample
lines.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

4-1

PERATION

O

4.4 OBTAINING MAXIMUM SENSITIVITY

If maximum sensitivity is desired, it is necessary to use an optimum combination of
settings on the SAMPLE, FUEL, and AIR pressure regulators. Settings must be
determined experimentally; however, the curves of Figures 4-1, 4-2 and 4-3 on the
following pages may be used as a guide.

1.0

0.8

F

IGURE

(100 ppm CH

4-1. T

S

RESPONSE

4

fullcale)

0.6
SAMPLE: 100 ppm CH
FUEL: 25 psig H
AIR: 25 psig

0.4

0.2

0

0 2 3 4 5 6 7

SAMPLE PRESSURE

(psig)

YPICAL CURVE OF ANALYZER RESPONSE VS

AMPLE PRESSURE

4

2

in N

2

. P

RESSURE SETTING ON

4-2

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

1.0

RESPONSE

(100 ppm CH

4

fullcale)

0.8

0.6

AIR: 30 psig

AIR: 30 psig

AIR: 30 psig

PERATION

O

F

IGURE

4-2. T

F

0.4

0.2

0

5

34.4

10

68.8

103.2

SAMPLE PRESSURE

SAMPLE: 100 ppm CH4 in N2 @ 5 psig

15

20

137.6

psig
kPa

YPICAL CURVES OF ANALYZER RESPONSE VS

UEL PRESSURE REGULATOR

1.0

FUEL: 30 psig H

0.8
FUEL: 25 ppm H

2

2

25

172.6

. P

RESSURE SETTING ON

30

206.4

RESPONSE

(100 ppm CH4 fullcale)

F

IGURE

748262-K Rosemount Analytical July 1997

4-3. T

A

YPICAL CURVES OF ANALYZER RESPONSE VS

IR PRESSURE REGULATOR

0.6

0.4

0.2

15

103.2

psig
kPa

2

20

137.6

25

172.6

. P

RESSURE SETTING ON

Model 400A Hydrocarbon Analyzer

30

206.4

4-3

FUEL: 20 ppm H

SAMPLE: 100 ppm CH4 in N2 @ 5 psig

0

5

34.4

10

68.8
AIR PRESSURE

PERATION

O

N

OTES

4-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

T

HEORY

5

5.1 PRINCIPLES OF OPERATION

The Model 400A Hydrocarbon 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 air and a fuel gas (hydrogen or a
hydrogen/diluent mixture). 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
electronic measuring circuitry. Current flow is proportional to the rate at which carbon
atoms enter the burner.

5.2 BURNER

Principle components of the burner are the manifold, burner jet, and the collector.

F

IGURE

5-1. F

Negative Ion
Collection Ring

+90V

Sample

LAME IONIZATION DETECTION THEORY

Signal Conditioning

Positive
Carbon
Ions

Air

Fuel

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

5-1

HEORY

T

Streams of sample, fuel and air delivered by the analyzer flow system (Section 5.3)
are routed through internal passages in the manifold and into the interior of the burner.
Here the sample and fuel pass through the burner jet and into the flame; the air
stream flows around the periphery of the flame.

The burner jet and the collector function as electrodes. The jet is connected to the
positive terminal of the 90 VDC polarizing voltage. The collector is connected to the
signal amplifier. The two polarized electrodes establish an electrostatic field in the
vicinity of the flame. The field causes the charged particles formed during combustion
to migrate. Electrons go to the burner jet; positive ions go to the collector. Thus a
small ionization current flows between the two electrodes. Magnitude of the current
depends on the concentration of carbon atoms in the sample. The burner current
serves as the input signal to the electronic measuring circuitry (Section 5.4).

Mounted on the burner are (1) igniter, driven by flame ignition circuit and (2) thermistor
sensor for flame status indicator circuit.

4

8
14

. T

IME FOR VARIOUS

F

IGURE

5.2.1 R

ANALYZER

RESPONSE

0

5-2. T

YPICAL CURVES OF DOWNSCALE RESPONSE VS

H

YDROCARBONS

ESPONSE TO DIFFERENT HYDROCARBONS

SAMPLE: CH
SAMPLE: C3H
SAMPLE: C6H

TIME

Both speed and magnitude of analyzer response are affected by the type of
hydrocarbon in the sample. Typical curves of response versus time for various
hydrocarbons are given in Figure 5-2.

5-2

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

HEORY

T

TYPE OF ATOM OCCURRENCE

EFFECTIVE CARBON

Carbon In Aliphatic Compound +1.00
Carbon In Aromatic Compound +1.00
Carbon In Olefinic Compound +0.95
Carbon In Acetylenic Compound +1.30
Carbon In Carbonyl Radical 0.00
Carbon In Nitrile +0.30
Carbon In Ether -1.00
Carbon In Primary Alcohol -0.60
Carbon In Secondary Alcohol -0.75
Carbon In Tertiary Alcohol, Ester -0.25

Chlorine

As two or more chlorine atoms on
single aliphatic carbon atom

Chlorine On Olefinic Carbon Atom +0.05

Value similar to that

Nitrogen In Amine

for oxygen atom in
corresponding alcohol

NUMBER

-0.12

Effective Carbon

Instrument response caused by atom of g iven type
Instrument response caused by aliphatic carbon atom

PPROXIMATE EFFECTIVE CARBON NUMBERS

T

ABLE

numbers =

5-1. A

Magnitude of the analyzer response to an atom of carbon depends on the chemical
environment of this atom in the molecule. The characteristic response of a given type
of atom may be expressed approximately by a value designated the "effective carbon
number." The effective carbon number of a particular type of carbon atom is defined
as the ratio between the instrument response caused by an atom of this type and the
instrument response caused by an aliphatic carbon atom. Table 5-1 lists approximate
effective carbon numbers for several types of carbon atoms. Although the instrument
does not respond directly to atoms other than carbon, in some compounds certain
other atoms do change instrument sensitivity to carbon. For this reason, values are
listed for a few non-carbon atoms. Values in the table were determined
experimentally, on a single analyzer. Because of slight variations in characteristics of
individual analyzers, these values should be regarded as approximations only.

To determine the effective carbon number of a molecule of a given organic compound,
algebraically add the individual values for the constituent atoms. Examples of
effective carbon numbers of molecules are: Butane (C4H10), 4; octane (C8H18), 8; and
ethyl alcohol (C2H5OH), 1.4.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

5-3

HEORY

T

5.3 ANALYZER FLOW SYSTEM

The internal flow system of the analyzer is shown in drawing 622883. Its basic
function is to deliver regulated flows of sample, fuel, and air to the burner. In addition,
the system routes the burner exhaust gas and sample bypass flow out of the analyzer
through the corresponding outlet ports.

Suitable pressurized gases are supplied to the SAMPLE, FUEL, and AIR inlet ports.
Each inlet fitting contains an internal filter.

Each of the three gas streams is routed to the burner via a flow control arrangement
consisting of the following elements:

1. An adjustable pressure regulator. The AIR and FUEL pressure regulators provide
controlled pressure on the downstream side. The SAMPLE pressure regulator is a
back-pressure regulator that provides controlled pressure on the upstream side,
and discharges excess sample through the BYPASS outlet. (Bypass feature
provides high velocity sample flow through analyzer, to minimize system response
time.)

2. A flow limiting element, selected to pass the appropriate gas flow when the
pressure drop is adjusted to the correct value. The air and fuel streams utilize
porous, sintered metallic restrictor elements mounted in fittings. The sample
stream uses a calibrated capillary tube.

3. A gauge that indicates pressure at the inlet end of the corresponding restrictor or
capillary. Ranges are SAMPLE pressure gau ge, 0 to 5 psig (0 to 35 kP a); AIR a nd
FUEL pressure gauges, 0 to 30 psig (0 TO 207 kPa).

5.4 PREAMPLIFIER BOARD

The ionization current generated by the burner is measured by an electrometer pre­amplifier located adjacent to the burner assembly. This small current is amplified and
transformed into a signal voltage that is then further amplified by a post amplifier
before being converted to a digital display suitable for direct data presentation. To
cover the required dynamic range, the amplifier is provided with two gain ranges that
differ by a factor of 100.

Output voltage from the preamp is a precise function of ionization current. In equation
form:

e

out = -i

i

x R

f

Where i
R

i

= ionization current

f

= feed back resistance

The most sensitive gain range includes a trim adjustment so that inter-range
correlation can be obtained over the entire signal span.

5-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

A buffer signal offering unity gain and noise filtration provide a low output impedance
to drive the signal cable and post amplifier circuits on the main circuit board. Selection
of the low or high range feedback resistors is made by relay K1 on the preamplifier
board. Refer to the preamplifier board schematic in the rear of this manual.

A variable offset current is injected into the summing node of the electrometer
amplifier to compensate for background offset current. These currents influence the
measurement procedure, and a variable voltage at the front panel allows the user to
visually cancel these currents during the calibration procedure. Background current is
due to unavoidable traces of carbonaceous material introduced into the burner flame
by the fuel gas and air.

5.5 MAIN ELECTRONICS BOARD

HEORY

T

5.5.1 P

OST AMPLIFIER

The post amplifier circuit comprises two amplifiers with various combinations of
feedback resistances that are logically selected by the front panel RANGE switch or
external inputs. The range selection process provides a total of seven possible gains
corresponding to the input sensitivities in Table 5-2.

RANGE

RANGE SWITCH

SETTING

PREAMP GAIN POST AMP GAIN

1 1 HIGH 50
2 2.5 HIGH 20
3 10 HIGH 5
4 25 HIGH 2
5 100 LOW 50
6 250 LOW 20
7 1000 LOW 5
8RMT -REMOTE

T

ABLE

5.5.2 D

5-2. I

NPUT SENSITIVITIES

IGITAL DISPLAY

The voltage originating from the signal amplifiers is made available to output terminals
and directly to an analog to digital (A-D) converter for data display in digital form. The
A-D converter is termed 3 1/4 digits, which implies a maximum reading of 1999. The
one bit signifying overrange allows 100% excursion above the normal 99.9% range.
Thus the user, depending upon span and zero offset conditions, may select the

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

5-5

HEORY

12

11

11

11

11

10

10

10

12

9

T

presentation to read directly in percent of fullscale and still have 100% overrange
capability remaining.

5.5.3 S

PAN

To compensate for various calibration gases, provision is made to vary the gain with a
variable span control. The variable span, accessed on the front panel through a
calibrated potentiometer, allows gain variation of 400%.

Table 5-3 gives the fullscale sensitivity of the current measuring circuitry for the
various settings on the RANGE switch and SPAN control.

RANGE SWITCH

FULLSCALE SENSITIVITY AMPS

SETTING MAX SPAN MIN SPAN

T

ABLE

5-3. F

15 x 10
22 x 10

35 x 10
42 x 10
55 x 10
62 x 10

-12

-

-

-

-

-

ULLSCALE SENSITIVITY

1.66 x 0

6.66 x 10

1.66 x 10

6.66 x 10

1.66 x 10

6.66 x 10

-12

-

-

-

-

-

5.5.3.1 R

ANGE TRIM (OPTION

)

The Range Trim will allow individual adjustment on each range to compensate for
different gas standards between ranges.

5.5.4 R

EMOTE RANGE CONTROL

Internally all of the range terminals are pulled up to the system 5V power supply
through 10K ohm resistors and are therefore suitable for connection to any TTL or
equivalent logic circuit. See Section 2.5.3.

5.6 HEATER/FAN TEMPERATURE ASSEMBLY

The temperature controller is located in the heated compartment of the instrument.
The RTD temperature sensor, in conjunction with a control circuit, maintains the
internal temperature to meet performance specifications for the instrument. The
temperature is controlled at 122°F (50°C). Refer to schematic drawing 624003 in the
rear of this manual.

This temperature is maintained at a constant level to minimize temperature dependent
variations in amplifier sensitivity and to prevent changes in absorption/desorption
equilibrium of trace hydrocarbons in the internal flow system. A blower fan runs
continuously to circulate air and equalize the temperature throughout the analyzer.

5-6

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

The temperature control board is a multi-purpose board with a control resistor that is
factory-selected for the model analyzer in which it is used. Schematic 624003 shows
the correct jumper position for the Model 400A

Note:
230 VAC operation requires an accessory transformer mounted external to the

instrument. If external 230 VAC power is provided, do not change the switch
setting on the temperature control board, which is factory-selected for 115 VAC.

A 230 VAC switch setting will cause the case temperature controller to
malfunction.

5.7 IGNITION CIRCUIT

The ignition circuit is used to light the burner flame during instrument startup. The
principle circuit components are as follows:

• Igniter element mounted in the burner cap

• Step-down transformer (PN 621049)

HEORY

T

• IGNITE switch mounted on the preamp board and connected in series with the
primary of the transformer

5.8 SYSTEM POWER SUPPLIES

Several power supplies are used within the Model 400A for the electrical functions.
These are as follows:

±±±±12 VDC

Used for most analog functions.

±±±±5 VDC

These two voltages derived from a precision reference are used for zero offset and
bias requirements.

+5 VDC

Used to power the digital circuit range decoding A-D display, etc.

+93 VDC

Used for the burner tip polarizing voltage.

+24 VDC

(unregulated) - Used for relays.
All of the power supplies are electronically regulated with the exception of the +24

VDC supply. Shorting of one supply to another may cause damage.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

5-7

HEORY

T

5.9 FLAME-OUT BOARD

Refer to schematic 657546 in the rear of this manual. Loss of the flame shuts down
the fuel solenoid. If there is a flammable component in the sample, a fail safe
solenoid accessory is available for wiring in parallel with the fuel solenoid.

5-8

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

S

ERVICE AND TROUBLESHOOTING

6

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.

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

The power plug must be disconnected from the rear of the instrument before
removing any of the boards and/or interconnect plugs.

6.1 SYSTEM CHECKOUT

If analyzer performance is unsatisfactory, make the following tests in the sequence
given.

MPLIFIER ZERO ADJUSTMENT

A

Place POWER switch at ON; RANGE switch at 1000; ZERO and SPAN
potentiometers at 1000. With flame extinguished, note reading on front panel
indicator, or on potentiometric recorder if used. Reading should be zero; if not, adjust
trimming potentiometer R13 on amplifier circuit board. Potentiometer R13 is adjusted
by inserting a screwdriver through the lower hole in the amplifier shield.

ERO CURRENT ADJUSTMENT

Z

If a current recorder is used, verify that it reads zero. If not, adjust trimming
potentiometer R1 on the current output board.

LECTRICAL LEAKAGE CHECK

E

Turn RANGE switch from position 1000 to position 1; indicator or recorder should still
read 0 ±5%. If reading is outside this range, leakage is excessive. To determine the
source of the leakage, disconnect the amplifier input cable from burner, and note
response of indicator or recorder. If abnormal reading persists, leakage is in either the
cable or electronics. If reading drops to zero, leakage is in the burner. Clean burner
per Section 6.2.1. Reconnect cable to burner.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

6-1

ERVICE AND TROUBLESHOOTING

S

LAME IGNITION

F

Start up analyzer per Section Three, and attempt to ignite flame. If f lame will not ignite
refer to Table 6-1, Item 2.

OISE CHECK

N

With flame burning, observe indicator or recorder. If noise is greater than 2% of
fullscale, refer to Table 6-1, Item 3.

VERALL SENSITIVITY CHECK

O

With flame burning, supply a suitable span gas to SAMPLE inlet. Turn RANGE switch
to a setting appropriate to the hydrocarbon content of the particular span gas. Adjust
SPAN control for reading of 100% on indicator or recorder. If the desired upscale
reading is unobtainable by adjustment of the SPAN control, the fault may be in either
the flow system (Table 6-1, Item 4) or in the electronics.

TABILITY CHECK

S

Supply zero gas to SAMPLE inlet. Turn RANGE switch to Position 1. Observe
indicator or recorder over several hours of operation. Drift greater than the stability
specification may be due to malfunctioning of the internal temperature control. For
comparison, Figure 6-1 shows the typical effect of ambient temperature variations on
background reading for a standard analyzer, with internal temperature controller
functioning normally. In this example, temperature dependent variations in background
signal are very small. However, note that such high stability is obtainable only with
exceedingly clean cylinder gases. Background signal, and temperature dependent
variations in this signal, increase with level of trace hydrocarbon contaminants.

If the internal temperature controller is functioning normally, apparent drift may be due
to changes in ambient temperature of the fuel and air cylinders. For further
information, refer to section 4.4, entitled "Obtaining Maximum Sensitivity."

6.2 SERVICING FLOW SYSTEM AND BURNER

In preventive maintenance of the flow system, the most important precautions are (1)
provision for continuous removal of all combustion products, including water vapor,
and (2) the use of great care to prevent the contamination of any component with
hydrocarbons, even in trace amounts.

CAUTION: COMPONENT COMTAMINATION

Never touch burner tip, Teflon skirt, or combustion chamber with bare hands;
always use clean gloves or cloth. If this precaution is not observed, oil from
skin will contaminate these components.

6-2

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

ERVICE AND TROUBLESHOOTING

S

6.2.1 B

URNER DISASSEMBLY AND CLEANING

Disassemble the burner only if contaminants must be removed. Combustion products
or other contaminants which accumulate inside the burner may form electrical leakage
paths between the collector and the burner contact, resulting in noisy readings. If the
instrument is to be operated at the highest sensitivity, traces of such contaminants can
cause erroneous readings. For best performance, it is necessary that the burner be
kept free of any contamination.

WARNING: POSSIBLE EXPLOSION HAZARD

This analyzer uses a fuel containing hydrogen. Leakage from the fuel
containment system can result in an explosion. The fuel supply and
containment system, both inside and outside the analyzer, should be carefully
checked for leaks upon installation, before initial startup, during routine
maintenance and any time the integrity of the containment system is broken.

When burner requires cleaning, refer to Figure 5-1 and DWG 623190 and proceed as
follows:

1. Place POWER switch at OFF position and disconnect power cord.

2. Shut off fuel gas first, then air and sample gases.

3. Unscrew burner cap retainer ring and remove burner cap.

4. On combustion chamber, disconnect polarizing voltage cable and amplifier input
cable.

5. Lift chimney from combustion chamber. Leave exhaust tubing connected to
chimney unless old chimney is to be replaced.

6. Loosen clamp. Lifting straight up, remove combustion chamber from manifold.

Note:
If old burner tip assembly is to be used again, do not touch it with bare hands or

any materials likely to contaminate it with hydrocarbons, salt, etc.

7. Unscrew and remove burner tip assembly.

Note:
All items used for cleaning (tweezers, swabs, etc.) must be absolutely free of

contamination.

8. Clean chimney assembly, combustion chamber, and burner tip assembly with
alcohol, followed by a distilled water wash.

748262-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

6-3

ERVICE AND TROUBLESHOOTING

S

Using care not to touch internal parts, reassemble burners as explained in the
following steps.

1. Holding burner tip assembly with clean tissue, screw finger-tight into manifold.

2. Push combustion chamber down onto manifold, taking care not to hit burner tip.
Tighten clamp on combustion chamber.

3. Replace chimney on combustion chamber.

4. Replace burner cap.

5. Reconnect all leads.

6.2.2 T

HERMISTOR

The thermistor sensor for the FLAME OUT indicator circuit is mounted in the burner.
See Figure 5-1. Thermistor resistance should be approximately 100K ohms at 77oF
(25oC). An alternate method requires that the comparator input signal be measured at
the junction of R32 and R33. When the flame is burning normally, the voltage at this
point will be 0.1 VDC to 0.3 VDC, indicating that the thermistor circuit is functional and
the flame temperature is correct.

6.2.3 F

UEL AND AIR RESTRICTORS

Fuel and air restrictors are porous, sintered metallic, restrictor elements mounted
within fittings. If a restrictor becomes plugged, replace it. Do not attempt to clean
restrictors with solvents. See DWG 622883.

6.2.4 S

AMPLE CAPILLARY

The sample capillary is equipped with fittings, permitting convenient removal and
replacement. If necessary, the capillary may be cleaned with acetone or methyl ethyl
ketone, followed by distilled water wash. Refer to warnings in Section 6.2.1.

6.3 TROUBLESHOOTING

For troubleshooting the electronic system, refer to the appropriate schematic at the
rear of this manual and Section 7. For troubleshooting the burner system, refer to
Table 6-1.

6-4

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

ERVICE AND TROUBLESHOOTING

S

SYMPTOM PROBABLE CAUSE POSSIBLE REMEDY

Indicator shows
upscale reading
when flame is out.

Burner will not
ignite.

Indicator reading
noisy

Electrical leakage in burner
assembly.

Fuel gas emerging from burner jet
diluted with other gases because
fuel system is insufficiently purged.

AIR and/or FUEL pressure
regulator improperly adjusted.

No flow, or reduced flow, of fuel
and/or air into burner combustion
chamber.

Malfunction in igniter circuit.

Ignite leads improperly connected.

Igniter burned out.

Transformer circuit open.

IGNITE switch defective.

Contamination of flow system: fuel
and air supplies, external pressure
regulators, connecting tubing.

Pressure regulator(s) and/or
pressure gauge(s) clogged.

Water or condensate in burner or
exhaust line.

Clean burner per Section 6.2.1

Purge FUEL pressure regulator
by allowing gas to flow for
several minutes, while turning
regulator alternately clockwise
and counterclockwise.

Check readings on AIR and
FUEL pressure gauges. Adjust
AIR pressure regulator to
increase or decrease air
pressure slightly.

Constriction in fuel and/or air
passage in burner jet, restrictor,
etc. Find cause of constriction
and remove.

Remove cap from burner.
Actuate IGNITE switch. Igniter
should glow red. If not, check
the following probable causes.

Check igniter plugs for proper
contact.

Replace igniter (glow plug) as
shown in drawing 623190.

Check voltage. See drawings
620424 and 655354

Test switch for continuity.
Replace if necessary.

Replace fuel and/or air supply;
clean or replace tubing and
regulators per Sections 2.5,
item 4.

Clean or replace regulators and
gauges.

Clean burner and exhaust line

T

ABLE

748262-K Rosemount Analytical July 1997

6-1. T

ROUBLESHOOTING (CONTINUED ON NEXT PAGE

)

Model 400A Hydrocarbon Analyzer

6-5

ERVICE AND TROUBLESHOOTING

S

SYMPTOM PROBABLE CAUSE POSSIBLE REMEDY

Loss of sensitivity

Sample pressure
fluctuations

Fuel and/or air filter clogged.

Plugged restrictor or capillary

Electrical elements of burner
partially short circuited by
combustion products

Check valve in sample pump not
functioning.

Obstruction in bypass outlet.

Check filters; replace if
necessary.

Verify that fuel and air
restrictors and sample capillary
are open. An abnormally low
background signal, together
with sensitivity loss, indicates
plugged restrictor. Note that
flame will not light unless fuel
and air restrictors are open, but
will not light even though
sample capillary is completely
closed.

Disassembly and clean burner,
as explained in Section 6.2.1.

Examine check valve.
Examine bypass outlet, remove

obstruction.

False flame
(FLAME-ON)
indication of span
gas produces little
or no upscale
deflection.

T

ABLE

6-1. T

ROUBLESHOOTING (CONTINUED FROM PREVIOUS PAGE

Flame may be lifting above burner
tip (unusual condition).

Connect a voltmeter from
ground, as viewed with door
open. If flame is properly lit, the
voltage will be below 0.2 VDC.
If voltage is high, readjust air­fuel ratio to obtain proper
ignition. Re-light burner with
richer fuel and air setting.

FUEL: 30 psig
AIR: 2 to 5 psig.

)

6-6

July 1997 Rosemount Analytical 748262-KModel 400A Hydrocarbon Analyzer

R

EPLACEMENT PARTS

7

WARNING: PARTS INTEGRITY

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

7.1 CIRCUIT BOARD REPLACEMENT POLICY

In most situations involving a malfunction of a circuit board, it is more practical to
replace the board than to attempt isolation and replacement of the individual
component. The cost of test and replacement will exceed the cost of a rebuilt
assembly. As standard policy, rebuilt boards are available on an exchange basis.

Because of the exchange policy covering circuit boards the following list does not
include individual electronic components. If circumstances necessitate replacement of
an individual component which can be identified by inspection or from the schematic
diagrams, obtain the replacement component from a local source of supply.

7.2 RECOMMENDED REPLACEMENT PARTS LIST

655208 Board, Temperature Control
815187 Regulator, Sample
620423 Board , Preamp
888692 Regulator, Fuel/Air
655305 Heater in Fan Assembly
861984 Gauge, Fuel/Air
836482 Fan, Heater
617900 Glow Plug (Igniter)
621031 Cable, 16 Conductor
644055 Gauge, Sample
748262 Instruction Manual, 400A (S/N 2000001 and up)
823484 Fuse, 2 AMP (115 VAC)
617902 Valve, Solenoid (Fuel Shutoff)
620446 Board, Flame-Out Relay
620428 Board, Amplifier
621023 Board, Isolated Current Output, 4 to 20 mA

7482626-K Rosemount Analytical July 1997

Model 400A Hydrocarbon Analyzer

7-1

EPLACEMENT PARTS

R

621017 Header
655178 Door, Clear Plastic
655203 Valve, Solenoid (Sample Shutoff) (Option)
017154 Filter, Sample/Air
898767 Filter, Mixed Fuel

See drawing 623190 for listing of capillaries and restrictors, and for Burner Parts List.

7-2

July 1997 Rosemount Analytical 7482626-KModel 400A Hydrocarbon Analyzer