Rosemount 951A NO/NOx Analyzer-Rev Y Manuals & Guides

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Rosemount Analytical

ODEL

NO/NO

NSTRUCTION MANUAL

951A

X ANALYZER

556383-Y

OTICE

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.

Manual Part Number 556383-Y July 2000 Printed in U.S.A.

Rosemount Analytical Inc.

4125 East La Palma Avenue Anaheim, California 92807-1802

ONTENTS

REFACE

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

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

CUSTOMER SERVICE, TECHNICAL ASSISTANCE AND FIELD SERVICE....P-4

RETURNING PARTS TO THE FACTORY.........................................................P-4

TRAINING ......................................................................................................P-4

DOCUMENTATION............................................................................................P-4

COMPLIANCES .................................................................................................P-5

ECTION

1.1 OVERVIEW..............................................................................................1-1

1.2 OPTIONS .................................................................................................1-2

ECTION

2.1 FACILITY PREPARATION........................................................................2-1

2.2 UNPACKING.............................................................................................2-1

2.3 GAS REQUIREMENTS.............................................................................2-5

2.4 SAMPLE REQUIREMENTS......................................................................2-6

2.5 GAS CONNECTIONS................................................................................2-7

2.6 ELECTRICAL CONNECTIONS.................................................................2-7

1. I

NTRODUCTION

2. I

NSTALLATION

2.1.1 Outline and Mounting Dimensions..............................................2-1

2.1.2 Location......................................................................................2-1

2.1.3 Power Requirements...................................................................2-1

2.6.1 Recorder Output..........................................................................2-7

2.6.2 Thermocouple Connections for Measuring Temperature of

NO2 to NO Converter....................................................2-7

2.6.3 Remote Range Change ..............................................................2-7

2.6.4 Connections of Range I.D. Kit.....................................................2-9

2.6.5 Power Connections.....................................................................2-9

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

ONTENTS

SECTION 3. STARTUP

3.1 STARTUP PROCEDURE......................................................................... 3-1

3.2 CALIBRATION......................................................................................... 3-3

3.3 MEASUREING EFFICIENCY OF NO2 TO NO CONVERTER AND

ADJUSTING TEMPERATURE SETPOINT .................................. 3-4

3.3.1 Test Setup for Measurement of Conversion Efficiency............... 3-4

3.3.2 Test Procedure........................................................................... 3-5

3.3.3 Subnormal Conversion Efficiency............................................... 3-9

3.3.4 Replacement of Converter.......................................................... 3-9

3.3.5 Capillaries................................................................................... 3-9

3.3.6 TEA Scrubber............................................................................. 3-9

SECTION 4. OPERATION

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

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

SECTION 5. THEORY

5.1 PRINCIPLES OF OPERATION................................................................. 5-1

5.1.1 Nitric Oxide Determination by Chemiluminescence Method........ 5-1

5.1.2 NOx Determination...................................................................... 5-1

5.1.3 Ozone Generation....................................................................... 5-2

5.2 ANALYZER FLOW SYSTEM................................................................... 5-2

5.2.1 Flow of Sample or Standard Gas to Reaction Chamber.............. 5-2

5.2.2 Flow of Air or Oxygen.................................................................. 5-3

5.2.3 Flow System Operating Modes ................................................... 5-4

5.2.4 Converter Bleed Flow.................................................................. 5-5

5.3 ELECTRONIC CIRCUITRY...................................................................... 5-5

5.3.1 Amplifier Board and Associated Circuitry ................................... 5-6

5.3.2 Valve Control Board, Front Panel Mode Switch and

Associated Circuitry...................................................... 5-7

5.3.3 ±15 Volt Power Supply.............................................................. 5-8

5.3.4 High Voltage Power Supply........................................................ 5-8

5.3.5 Converter Temperature Control Board and Associated

Elements....................................................................... 5-9

5.3.6 Fan Control Circuit......................................................................5-10

5.3.7 Remote Operation Option........................................................... 5-10

5.3.8 Range I.D. Option....................................................................... 5-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

SECTION 6. SERVICE AND MAINTENANCE

6.1 SYSTEM CHECKS AND ADJUSTMENTS................................................6-1

6.2 SERVICING FLOW SYSTEM....................................................................6-6

6.2.1 Sample Capillary..........................................................................6-6

6.2.2 Ozone Restrictor and Capillary....................................................6-7

6.2.3 Replacing NO2 to NO Converter..................................................6-8

6.2.4 Cleaning Reaction Chamber........................................................6-10

6.2.5 Photomultiplier Tube and Housing...............................................6-12

6.2.6 Teflon Liner in Lamp Housing of Ozone Generator.....................6-13

6.3 SERVICING ELECTRONIC CIRCUITRY ..................................................6-14

SECTION 7. REPLACEMENT PARTS

ONTENTS

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

7.2 REPLACEMENT PARTS...........................................................................7-1

7.2.1 Pneumatics.................................................................................7-6

7.2.2 Converter Assembly....................................................................7-7

7.2.3 Low Tempco Option ....................................................................7-9

ENERAL PRECAUTIONS FOR HANDLING

ARRANTY

IELD SERVICE AND REPAIR FACILITIES

TORING HIGH PRESSURE CYLINDERS

& S

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

iii

ONTENTS

IGURES

1-1 Model 951A NO/NOx Analyzer.................................................................... 1-1

2-1 Model 951A Outline and Mounting Dimensions .......................................... 2-2

2-2 Front Panel Indicators and Controls............................................................ 2-3

2-3 Controls and Adjustments Located Behind Swing-Out Front Panel............ 2-3

2-4 Rear Panel.................................................................................................. 2-3

2-5 Remote Range Kit Installed......................................................................... 2-8

2-6 Typical Interconnection of Remote Range Kit............................................. 2-8

3-1 Amplifier Board Adjustments....................................................................... 3-4

3-2 Measuring Efficiency of NO2 to NO Converter............................................ 3-7

3-3 Conversion Efficiency as a Function of Converter Temperature................. 3-8

5-1 Schematic Flow Diagram of Model 951A.................................................... 5-2

5-2 Functional Schematic Diagram of Electronic Signal Circuitry...................... 5-5

6-1 Amplifier Board............................................................................................ 6-3

6-2 NO2 to NO Converter Assembly.................................................................6-9

6-3 Reaction Chamber/Photomultiplier Assembly............................................. 6-10

6-4 Reaction Chamber Assembly and Phototube Housing ............................... 6-11

6-5 Ozone Generator........................................................................................6-13

6-6 Terminal Chassis Wiring Diagram............................................................... 6-15

7-1A Model 951A................................................................................................. 7-2

7-1B Model 951A................................................................................................. 7-3

7-1C Model 951A................................................................................................ 7-4

7-2 Electronics................................................................................................... 7-5

7-3 Front Panel Pneumatics Components......................................................... 7-6

7-4 Converter Components............................................................................... 7-7

7-5 Ozone Generator Components................................................................... 7-8

7-6 Tempco Reftrofit Component Location........................................................ 7-9

ABLES

2-1 Model 951A Controls and Adjustments.................................................... 2-4

3-1 Proper Gas Supply Pressures for Various Levels of Sample NOx........... 3-3

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

DRAWINGS (LOCATED IN REAR OF MANUAL)

619604 Schematic Diagram, Computer Interface 619710 Schematic Diagram, ±15V Power Supply 641871 Schematic Diagram, Temp Control 649819 Schematic Diagram, Amplifier Board 649822 Diagram, Tubing - Model 95A 649834 Schematic Diagram, 951A NO/NOx Analyzer 649835 Pictorial Wiring Diagram, Model 951A NO/NOx Analyzer 649958 Flow Diagram, Model 951A 652423 Schematic Diagram, Power Supply 652834 Schematic Diagram, Power Supply - Thermocooler 652838 Pictorial Wiring Diagram, Low Tempco Option 654348 Schematic Diagram, Hi Voltage Board Assembly 656313 Schematic Diagram, Valve Control Board 780350 Schematic Diagram, 4-20mA 0-5V Option 780726 Wiring Diagram, 4-20mA 0-5V Option 780727 Installation Drawing, Model 951A w/4-20mA 0-5V Option

780809 Wiring Diagram, 4-20mA 0-5V Option and Low Tempco

ONTENTS

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

ONTENTS

OTES

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

REFACE

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 955A should be thoroughly familiar with and str ictly follow the instructions in this manual. Save these

instructions.

If this equipment is used in a manner not specified in these instructions, protective systems may be impaired.

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 ca n 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.

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

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

REFACE

WARNING: ULTRA VIOLET LIGHT HAZARD

UV light from the ozone generator can cause permanent eye damage. DO NOT LOOK DIRECTLY AT THE UV SOURCE IN THE OZONE GENERATOR. Use of UV filtering glasses is recommended.

WARNING: OZONE HAZARD

This instrument generates ozone while operating. Ozone is toxic by inhalation and is a strong irritant to the throat and lungs. Ozone is also a strong oxidizing agent. Its presence is detected by a characteristic pungent odor.

The instrument EXHAUST outlet contains ozone and nitrogen dioxide which is toxic by inhalation. The BYPASS outlet contains various oxides of nitrogen, and if the sample source is from the exhaust of an internal combustion engine, it may contain unburned hydrocarbons and carbon monoxide which is highly toxic and, depending on duration of exposure, can cause headache, nausea, loss of consciousness and death.

Avoid any inhalation of the internally generated ozone, sample, EXHAUST and BYPASS discharge. Keep all tubing fittings checked for tightness to avoid internal leaks.

Connect rear panel EXHAUST and BYPASS outlets to outside vent via se parate lines 1/4 inch (6.3mm) or larger. Use only Teflon or stainless steel tubing.

WARNING: PARTS INTEGRITY

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

CAUTION: AIR FLOW

Do not operate instrument without air flow to the ozonator; plugging of the filter will result.

CAUTION: HIGH PRESSURE GAS CYLINDERS

This instrument requires use of oxygen and a known standard gas in high pressure cylinders. Refer to Handling and Storing High Pressure Gas Cylinders located in the rear of this manual.

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

SPECIFICATIONS

REFACE

ATALOG NUMBER

ANGES

SENSITIVITY

INEARITY

ESPONSE TIME

TANDARD SAMPLE

APILLARY

UXILIARY SAMPLE

APILLARY

RECISION

TABILITY

ERO

193702 Model 951A NO/NOx Analyzer Selectable fullscale range of 10, 25, 100, 250, 1000, 2500 and

10,000 parts per million

0.1 ppm on 10 ppm range ±1% of fullscale

The specified linearity is obtainable throughout the operating range, contingent upon use of an appropriate combination of oxygen source gas, gas pressure settings and electronic adjustments.

LECTRONIC PLUS FLOW

Approximately one second on all ranges except 10 ppm. Approximately three seconds on 10 ppm range.

Five seconds on all ranges. For such applications as monitoring stack sources, where

comparatively slow response is desired, an internal switch provides an optional electronic response time of approximately 10 seconds to 90% of fullscale on all ranges.

±5% of fullscale

1% of fullscale in 24 hours

)

PAN

ETECTOR OPERATING

EMPERATURE

ECORDER OUTPUT

MBIENT TEMPERATURE

LECTRICAL POWER

EQUIREMENTS

IMENSIONS

EIGHT

1% of fullscale in 24 hours Atmospheric Selectable output of 10 millivolts, 100 millivolts, 1 volt or 5 volts

40°F to 100°F (4.4°C to 37.7°C) 107 to 127 VAC, 50/60 Hz, 1000 watts

9.0 x 17.8 x 22.0 inches (228.6 x 450.9 x 558.8mm) HxWxD 76 lbs (34.5 kg)

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

REFACE

USTOMER SERVICE

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

, T

ECHNICAL ASSIST ANCE AND FIELD SERVICE

Rosemount Analytical Inc.

Process Analytical Division

Customer Service Center

1-800-433-6076

RETURNING 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 returnin g any pro duct o r compon ent t hat has be en expo sed to a toxic, corrosi ve 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.

Return to:

Rosemount Analytical Inc.

4125 East La Palma Avenue

Anaheim, California 92807-1802

USA

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 Depart men t at:

Rosemount Analytical Inc.

Phone: 714-986-7600

FAX: 714-577-8006

OCUMENTATION

The following Model 951A NO/NOx Analyzer instruction materials are available. Contact Customer Service or the local representative to order.

556383 Instruction Manual (this document)

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

OMPLIANCES

This product may carry approvals from several certifying agencies, for use in nonhazardous, indoor locations

97-C218

REFACE

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

REFACE

OTES

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

NTRODUCTION

1.1 OVERVIEW

The Model 951A NO/NOx Analyzer continuously analyzes a flowing gas sample performing one of two switch selectable determinations:

1. Nitric oxide (NO); or

2. Combined nitric oxide (NO) and nitrogen dioxide (NO,) designated NOx. By definition [NOx] = [NO] + [NO2].

Typical applications include analyzing vehicular exhaust emissions from internal combustion engines and monitoring the effluent from stationary (stack) sources

The analyzer utilizes the chemiluminescent method of detection In the nitric oxide determination, sample NO is quantitatively converted into NO2 by gas-phase oxidation with molecular ozone produced within the analyzer from air or oxygen supplied by an external cylinder. A characteristic of this reaction is the elevation of approximately 10% of the NO2 molecules to an electronically-excited state, followed by immediate reversion to the non-excited state accompanied by emission of photons.

The emitted photons impinge on a photomultiplier detector generating a low-level DC current. The current is amplified to drive a front panel meter and an accessory potentiometric recorder if desired.

SPAN

ZERO

PPM RANGE

250 1000

100 2500

25 10000 10 AUTO

NALYZER

CONVERTER

ADJUST

Model 951A N O /NO x A nalyzer

IGURE

1-1. M

NO NOx

OFF

Rosemount Analytical

ODEL

951A NO/NOX A

MODE

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

1-1

NTRODUCTION

To minimize noise and reduce dark current, the photomultiplier tube is mounted in a thermoelectrically-cooled housing with temperature held constant at about 59oF (15oC). Control circuitry is contained in the 652831 Cooler Temperature Controller/Power Supply Assembly. The power supply circuit provides a high-current source of DC voltage. A thermistor sensor attached to the housing, and an associated switching transistor, control a pass transistor, providing closely regulated on-off control.

Attached to the cooler housing is thermal fuse F3, setpoint 150oF (65oC). This fuse protects the thermoelectric cooler against the overheating that otherwise could occur as a result of excessively high ambient temperature or failure of a fan.

CAUTION: EXCESSIVE HEAT

Do not operate this analyzer without the air duct covering the cooling fins of the thermoelectric cooler. Excessive heat may damage the cooling devices. The cooler indicator lamp DS1 (mounted on the upper left side of the inner flow regulator panel and can be viewed through the window) will cycle on and off until a control point is reached.

Analyzer functioning for the NOx determination is identical to that described above for the NO determination except that, before entry into the reaction chamber, the sample is routed through a converter where the NO2 component is dissociated to form NO. Instrument response is proportional to total NO in the converted sample, that is the sum of the NO present in the original sample plus the NO produced by dissociation of NO2.

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

The electronic circuitry is modularized, utilizing plug-in p rinted circuit boards with solid state components and test jacks for easy troubleshooting and replacement.

If desired, the Model 951A may be factory equipped with various optional features in addition to the standard features of the basic instrument. Brief descriptions of the principal options are given in the following section.

1.2 OPTIONS

ANGE

I.D.

1-2

This option provides contact closure signals that enable a computer or other external device to identify the setting of the front panel PPM RANGE Switch. The Model 7D Thermal Conductivity Analyzer is designed to continuously measure the concentration

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

NTRODUCTION

of a single component of interest in a flowing gas mixture. The measurement is based on the different thermal conductivity's of the individual components of the sample stream. The method is especially well suited to analysis of two-component sample streams. However, analysis of multi-component streams is possible if the various components of the background gas occur in relatively constant ratio, or have similar thermal conductivity's.

EMOTE RANGE CHANGE

For applications where remote operation of the analyzer is desired, as in an emission test console, the Remote Range Change Option may be used. This option permits either the operator or a computer to override and disable the front panel MODE and PPM RANGE Switches and thus to control selection of: (a) NO or NOx mode, and (b) parts-per-million range.

The unit consists of an electrical plug connector with plug-in logic card and harness for connection to a rear panel terminal strip on the analyzer.

ANGE

AND REMOTE RANGE CHANGE

I.D.

The Range I.D./Remote Range Change Option is a combination of the Range I.D. and Remote Range Change options. This option is compatible with a user supplied remote control system employing a 24 VDC digital output and input for analyzer range control and analyzer range sense, respectively. It is completely integral within the analyzer and provides a terminal strip on the rear of the analyzer for connections of the user cable.

AMPLE PUMP

The basic Model 951A is designed to accept pressurized samples. To permit analysis of gases at atmospheric or sub-atmospheric pressure the analyzer may be equipped with an optional, internally mounted sample pump. This option is not available on Low Tempco versions of the 951A. An external, accessory pump can be ordered instead.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

1-3

NTRODUCTION

OTES

1-4

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

NSTALLATION

2.1 FACILITY PREPARATION

Sections 2.1.1 through 2.1.3 provide information that may be required prior to installation of the analyzer.

2.1.1 O

2.1.2 L

2.1.3 P

UTLINE AND MOUNTING DIMENSIONS

Significant dimensions are shown in Figure 2-1.

OCATION

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. A circuit controlled by a thermal switch holds internal temperature of the analyzer to the correct operating temperature for ambient temperatures in the range 40oF to 100oF (4.4oC to 37.7oC). Temperatures outside

these limits necessitate use of special temperature controlling equipment or environmental protection.

Preferably, the cylinders of air (or oxygen) and span gas should be located in an area of relatively constant ambient temperature.

OWER REQUIREMENTS

Electrical power requirements are 107 to 127 VAC, 50/60 Hz, 1000 watts.

2.2 UNPACKING

Unpack instrument carefully. Preparatory to shipment, the photomultiplier tube housing and the sample pump (if instrument is so equipped) are immobilized with hold down screws, inserted from the bottom of the instrument and marked with red paint for identification. The hold down screws must be removed prior to operation of the instrument. In the event the instrument is ever returned to the factory, these screws must be replaced to ensure safe shipment.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

2-1

NSTALLATION

[

]

[

]

19.0

[482]

8.7

[222]

8.7

[221]

7.0

[178]

1.25 [32]

9.0

[228]

4.5 114

2.0

[51]

6.0

[152]

20.2

[513]

18.3

[465]

1.0

[25.4]

1.25 [32]

6.6

168

4.6

[118]

2.8

[70]

DIMENSIONS

Inch

3. ALLOW 16 INCHES IN FRONT OF INSTRUMENT FOR DOOR SWING.

2. ALLOW 12 INCHES MINIMUM CLEARANCE ABOVE INSTRUMENT FOR MAINTENANCE..

1. RECOMMENDED MOUNTING HARDWARD: 10-32 MACHINE SCREWS (SUPPLIED BY CUSTOMER).

IGURE

2-1. M

ODEL

951A O

2-2

18.3

[465]

18.3

[465]

18.3

[465]

18.3 [465]

RECOMMENDED PANEL CUTO UT

UTLINE AND MOUNTING DIMENSIONS

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

8.5

[216]

∅.25

[63]

6 PLC'S

NSTALLATION

AC POWER ON/OFF SWITCH

IGURE

2-2. F

PHOTOMULTIPLIER HIGH VOLTAGE INTERLOCK SWITCH

RECORDER OUTPUT SELECT SWITCH

SPAN ADJUST

250 100

25 10

1000 2500 10000 AUTO

ZERO ADJUST

SAMPLE PRESSUR E GAUGE

B Y P A

FLOW

BALANCE

Rosemount Analytical

MODE SWITCH

PPM RANGE SWITCH

CONVERTER ADJUST

CONVERTER INDICATOR

RONT PANEL INDICATORS AND CONTROLS

RESPONSE TIME SELECTOR SWITCH

FAST SLOW

100

RESPONSE

REC

OUTPUT

R22

R34 ALIB

R16

R33

R31

INP

R32

BYPASS NEEDLE VALVE

B Y P A

FLOW

BALANCE

OZONE

OZONE PRESSURE GAUGE

OFF

BYPASS FLOWMETER

OZONE PRESSURE REGULATOR

OZONE OFF PUSHBUTTON SWITCH

OFF

IGURE

2-3. C

THERMOCOUPLE CONNECTOR TB9

IGURE

2-4. R

IR INLET

EXHAUST

Rosemount Analytical

FLOW BALANCE NEEDLE VALVE

Model 951A NO/NOx Analyzer

SAMPLE BACKPRE SSURE REGULATOR

ONTROLS AND ADJUSTMENTS LOCATED BEHIND SWING OUT FRONT

ANEL

SAMPLE INLET

RECORDER CONNECTION TB4-1

RECORDER CONNECTION TB4-2

RANGE I.D. CONNECTOR J10 (Option)

CABLE GLAND FOR RECORDER CABLE

AC POWER CABLE

FUSE F1 FUSE F2

EAR PANEL

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

2-3

NSTALLATION

CONTROL FUNCTION

ON/OFF MODE S

WITCH

METER

PPM RANGE S

CONVERTER

ADJUST

ZERO

SPAN

SAMPLE

BACKPRESSURE REGULATOR AND PRESSURE GAUGE

BYPASS F

AND

OZONE

REGULATOR AND GAUGE

OZONE OFF

LOWMETER

EEDLE VALVE

PRESSURE

SWITCH

WITCH

Controls AC power to all components in instrument For selection of NO or NOx

Readout of NO or NOx in ppm as selected with MODE switch. Upper scale is graduated 0 to 100 for use with 10, 100, 1000, and 10,000 ppm ranges. Lower scale is graduated 0 to 25 for use with 25 and 2500 ppm ranges.

Select fullscale range for meter and recor der LED illuminates during application of power to converter

heater. When Converter reaches temperature equilibrium, LED will go off and on at intervals of about 2 seconds, indicating correct temperature control.

Through-panel screwdriver adjustment of converter temperature. Should be set for temperature that yields optimum combination of high efficiency for the NO2 to NO conversion and extended life for the catalytic converter. Optimum temperature differs from one instrument to another, see Section 3.3.

Set zero point on meter scale or recorder chart. With MODE switch in NO position and zero air supplied to SAMPLE inlet, ZERO Control is adjusted for zero reading.

Set upscale calibration point on meter scale or recorder chart. MODE switch is at NO or NOx and suitably pressurized standard gas of accurately known NO/NOx content is supplied to SAMPLE inlet. With PPM RANGE switch set to the appropriate range for the span gas, the SPAN control is adjusted to correct reading on meter or recorder.

Adjustment and indication of pressure (and therefore flow) of sample or standard gas routed through sample capillary, and into reaction chamber. Proper setting dependent on operating range. See Table 3-1.

Bypass flow indication and adjustment for sample or standard gas to SAMPLE inlet. Setting of 2 L/min. is recommended to ensure rapid response and optimum functioning of sample backpressure regulator

Pressure adjustment and indication for air or oxygen supplied to AIR inlet for use as oxygen source for internal ozone generator. Oxygen is usable for all ranges. Air is usable only for 2500 ppm range or lower. Proper pressure setting dependent on operating rang e, see Tabl e 3- 1.

Removes AC power to ultraviolet source lamp in ozone generator. Power is OFF when switch indicator is red.

ABLE

2-4

2-1. M

PAGE

ODEL

)

951A C

ONTROLS AND ADJUSTMENTS (CONTINUED ON NEXT

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

CONTROL FUNCTION

FLOW BALANCE

NEEDLE VALVE

RESPONSE TIME

SELECTOR SWITCH

RECORDER OUTPUT

SELECTOR SWITCH

ETER MECHANICAL

ZERO

NSTALLATION

Use to equalize pressure drop for NO and NOx legs of the internal flow system. Criterion for correct adjustment is an NO2 free nitric oxide standard gas should give equal readings of ppm for NO and NOx modes. An alternate flow balance check , if NO2 free standard gas is unavailable, is to verify that the reading on the SAMPLE pressure gauge is the same for NO and NOx modes.

Select either FAST or SLOW electronic response. When set to FAST, electronic response time (for 0 to 90% of fullscale) is then approximately one second for all ranges except 10 ppm, which is approximately three seconds. When set to SLOW (as in monitoring stack sources), electronic response time 0 to 90% of fullscale) is approximately ten seconds for all ranges.

To select output of 10 mV, 100 mV, 1V or 5 V for a potentiometric recorder.

Located on rear of meter. With AC power OFF, meter should read zero. If not use screw adjustment on meter.

ABLE

HOTOMULTIPLIER HIGH

OLTAGE INTERLOCK

WITCH

2-1. (

CONTINUED FROM PREVIOUS PAGE

When analyzer front panel is open, photomultiplier high voltage power supply is automatically shut off.

)

2.3 GAS REQUIREMENTS

WARNING: HIGH PRESSURE GAS CYLINDERS

This instrument requires use of oxygen and a known standard gas in high pressure cylinders. Refer to Handling and Storing High Pressure Gas Cylinders located in the rear of this manual.

IR OR OXYGEN

This is used as both (a) oxygen source for generation of the ozone required for the chemiluminescent reaction, and (b) standard gas for zero calibration. Gas for both purposes may be supplied from a single cylinder and routed through a tee. Alternatively, two separate cylinders may be used.

Oxygen is usable in all applications. Air is suitable for the oxygen source only if the desired fullscale operating range is 2500 parts-per-million or less. Breathing grade oxygen or air is recommended. Clean, dried ambient air containing less than 0.1 parts-per-million nitric oxide may be used, provided that its de wpoint is below -10oF (23oC). If air is insufficiently dried, or contains excessive nitric oxide, instrument response will not be linear to 2500 ppm.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

2-5

NSTALLATION

PAN GAS

This is a standard gas of accurately known composition, used to set an upscale calibration point.

Alternative span gases are:

1. The usual span gas is NO in a background of nitrogen.

2. For span check or adjustment in the NOx mode, the span gas may be NO2 in a background of air or nitrogen.

3. For convenient calibration in either the NO or NOx mode, the span gas may be a cylinder gas mixture consisting of known concentrations of both NO and NO2 in a background of nitrogen.

Note For maximum calibration accuracy, the concentration of NO and/or NO2 in the

span gas should be as near as possible to that in the sample gas. Also, the span gas should be supplied to the rear panel SAMPLE inlet at the same pressure as the sample gas. To ensure constant pressure, a pressure regulator may be utilized immediately upstream from the SAMPLE inlet.

Preferably, each gas used should be supplied from a tank or cylinder equipped with a clean, non-corrosive type two stage regulator. In addition, a shut-off valve is desirable. If possible, install the gas cylinders in an area of relatively constant ambient temperature.

2.4 SAMPLE REQUIREMENTS

The Sample must be relatively clean and dry before entering the analyzer. In general, before admission to the analyzer, the sample should be filtered to 2 microns and should have a dewpoint below 90oF (32oC). The factory can provide technical assistance if desired .

Proper supply pressures for sample and span gases depend on whether or not the analyzer is equipped with the optional 632748 Sample Pump:

For the basic Model 951A, without sample pump, sample must be supplied to the SAMPLE inlet at a pressure of 5 to 10 psig (34.5 to 69 kPa). This ensures that the normal bypass flow of two liters per minute will be obtainable by adjustment of the BYPASS Needle Valve. (Proper bypass flow is essential for rapid system response and stable flow into reaction chamber.)

For an analyzer equipped with sample pump, the acceptable pressure range at the SAMPLE inlet is 0 to 5 psig (0 to 34.5 kPa). The pump pressurizes the sample to between 5 and 10 psig (34.5 to 69 kPa) for supply to the internal flow system.

2-6

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

2.5 GAS CONNECTIONS

1. Remove plugs and caps from all inlet and outlet fittings. See Figure 2-4.

2. Connect EXHAUST outlet to outside vent via tubing with O.D. of 1/4 inch (6.3mm) or larger.

3. Connect external lines from air (or oxygen) cylinder and sample source to corresponding rear panel inlet ports. For sample line, stainless steel tubing is recommended.

4. Adjust regulator on air (or oxygen) cylinder for output pressure of 35 to 40 psig (251 to 276 kPa).

Supply sample gas to rear panel SAMPLE inlet at appropriate pressure: 5 to 10 psig (34.5 to 69 kPa) for basic analyzer without sample pump; 0 to 5 psig (0 to 34.5 kPa) for analyzer with pump.

2.6 ELECTRICAL CONNECTIONS

NSTALLATION

2.6.1 R

ECORDER OUTPUT

If a recorder is used, connect leads to terminals marked REC 1 (+) and 2 (-) on TB4 (Figure 2-4). (Note that, within the analyzer, the negative recorder output terminal is connected to ground.)

Set REC OUTPUT Selector Switch SW1 (Figure 2-3) to the recorder span: 10 mV, 100 mV, 1 VDC or 5 VDC.

2.6.2 T

HERMOCOUPLE CONNECTIONS FOR MEASURING TEMPERATURE OF

NO C

ONVERTER

Temperature of the NO2 to NO converter may be monitored by connecting a customer supplied millivolt meter to thermocouple connector TB9 located on the rear panel (Figure 2-4). The position of the thermocouple in the converter bundle will influence the actual temperature readout.

2.6.3 R

EMOTE RANGE CHANGE

The Remote Range Change Kit, Figure 2-5, consists of a plug-in Adapter Board plus attached harness and rear terminal plate.

The Adapter Board has two two-position slide switches: the MAN/AUTO MODE Switch and the MAN/AUTO RANGE Switch.

The MAN/AUTO MODE Switch provides the choice of local or remote control of the NO/NOx Mode Switching Solenoid Valve, assoc iated with the NO2 to NO converter. With switch at MAN, the function is under control of the front panel MODE Switch. With switch at AUTO, the front panel MODE Switch is disabled; the function is then remotely controlled, by either the operator or a computer, via contact closure signals applied to terminals on TB5.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

2-7

NSTALLATION

The MAN/AUTO RANGE Switch provides the choice of local or remote selection of operating range. With switch at MAN, range selection is under control of the front panel PPM RANGE Switch. With switch at AUTO, the front panel PPM RANGE Switch is disabled; range selection is remotely cont rolled, by either the operator or a computer, via contact clos ure sign als appli ed t o ter min als o n TB6.

Control at TB5 and TB6 is accomplished by a contact closure from the terminal marked COM (for common) to the terminal marked with the name of the desired function. Contact closure requirements are 25 mA at 15 VDC.

FAST SLOW

RESPONSE

100

OUTPUT

Computer Adapter Board

Auto/Man Range Switch

REC

R22

R34

CALIB

R16

R33

INPUT

R31

R32

MODE

AUTO

RANGE AUTO MAN

Rosemount Analytical

Electronics Assembly

DC Harness (J1) Auto/Man Mode

Switch

NOx SPAN ZERO

1000 2500

10,000

10 25

100

IGURE

2-5. R

2-6. T

Computer Adapter Board installed on Interconnect Board of the Electronics

Terminal Assembly mounted on rear panel of Model 951A

Assembly

EMOTE RANGE KIT INSTALLED

TERMINAL

ASSEMBLY

Remote MODE

SELECT SWITCH

NOx SPAN ZERO

COM

100 250

10 25

Remote RANGE

SELECT SWITCH

1000 2500

10,000

COM

With all contacts of Range Select Switch open, analyzer is ion 250 ppm range.

YPICAL INTERCONNECTION OF REMOTE RANGE KIT

2-8

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

NSTALLATION

2.6.4 C

ONNECTIONS OF THE RANGE

I. D. K

The Range I.D. option provides contact closure signals that permit a computer or other external device to identify the position selected manually with the front panel PPM RANGE Switch. The cable is connected to PPM RANGE Switch SW1 and extends to connector J10 mounted on the rear of the case (Figure 2-4).

The pin-out connections of J10 are as follows:

Pin A 10 ppm Pin B 25 ppm Pin C 100 ppm Pin D 250 ppm Pin E 1000 ppm Pin F 2500 ppm Pin H 10000 ppm Pin J Wiper

2.6.5 P

OWER CONNECTIONS

Connect power cord to an AC source of 107 to 127 volts, 50/60 Hz. If power outlet does not have third (ground) contact, use an adapter to provide proper grounding.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

2-9

NSTALLATION

OTES

2-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

TARTUP

Preparatory to startup and operation, a thorough familiarization with Table 2-1 and Figures 2-2, 2-3 and 2-4 is recommended. These figures give locations and brief descriptions of operating controls. For more detailed information on controls, refer to Section Five.

3.1 STARTUP PROCEDURE

Following are detailed stepwise instructions on startup and calibration. For convenience, condensed instructions for startup, routine calibration and normal operation are provided at the front of this manual.

1. W ith power removed from analyzer, check front panel meter. It should read zero; if not, adjust Mechanical Zero Screw at rear of meter for zero reading.

2. Place front panel PPM RANGE Switch at 1000.

WARNING: OZONE HAZARD

When instrument power is on, the ultraviolet source sample is energized, converting a portion of the oxygen contained with the ozonator into ozone. With normal flow through the ozonator, the ozonized air or oxygen is continuously swept though the ozonator and into the reaction chamber. If flow is stopped, however, the ozone will diffuse and will attack the sintered metallic restrictor element in the tee fitting at the upstream end of the ozonator. Operation of the analyzer with the restrictor element thus rusted will result in the following consequences: Reduced flow of air or oxygen through the ozonator, ozone deprivation within the reaction chamber and non-linear response of the analyzer to NO/NOx.

To prevent such damage, verify that the front panel ozone ON/OFF switch is turned off if flow of feed gas to the air inlet is terminated.

3. Set front panel MODE Switch at NO or NOx. Place POWER Switch at ON. Electrical power is now being supplied to all circuits, including sample pump if analyzer is so equipped. Analyzer will now require approximately one hour for temperature equilibration before ready for calibration.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

3-1

TARTUP

4. Establish correct pressure for air oxygen: a. Verify that pressure regulator on cylinder of air or oxygen is set for supply

pressure of 35 to 40 psig (242 to 276 kPa).

a. On internal gas control panel, Figure 2-3. adjust OZONE Pressure Regulator so

that OZONE Pressure Gauge indicates either 20 psig (138 kPa) or 30 psig (207 kPa), depending on the desired operating range.

5. Establish correct flow of sample gas: a. Supply sample gas to rear panel SAMPLE inlet. b. Adjust SAMPLE Backpressure Regulator so SAMPLE Pressure Gauge

indicates the value appropriate to the desired operating range.

c. Adjust BYPASS Needle Valve for reading of two liters per minute on BYPASS

Flowmeter.

Note Inability to obtain a bypass flow of two liters per minute by adjustment of the

BYPASS Needle Valve usually indicates insufficient sample supply pressure at the SAMPLE inlet.

6. Establish correct flow of zero air: a. Supply zero air to rear panel SAMPLE inlet. b. Note reading on SAMPLE Pressure Gauge. It should be the same as in Step

5b. If not, adjust output pressure regulator on air cylinder as required.

7. Establish correct flow of upscale standard gas: a. Supply upscale standard gas to rear panel SAMPLE inlet. b. Note reading on SAMPLE Pressure Gauge. It should be the same as in Step

5b. If not, adjust output pressure regulator on cylinder of upscale standard gas as required.

Note Supply pressures for sample and upscale standard gases must be the same;

otherwise, readout will be in error.

The Analyzer is now ready for calibration per Section 3.2.

3-2

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

TARTUP

ABLE

Max. NOx Level

(ppm)

1000 Air

2500 Air

10,000 Oxygen

3-1. P

ROPER GAS SUPPLY PRESSURES FOR VARIOUS LEVELS OF SAMPLE

Gas Supplied

to Air Inlet

3.2 CALIBRATION

1. Zero Calibration. a. Set PPM RANGE Switch for the same range that will be used during sample

analysis. Set SPAN Control at about midrange. b. Supply zero gas to rear panel SAMPLE inlet. c. Adjust ZERO Control for zero reading on meter or recorder, then lock ZERO

Control knob.

Ozone

Pressure Gauge Setting

20 psig (138 kPa)

Provides flow of a cc/min to ozone generator

30 psig (207 kPa)

Provides flow of a cc/min to ozone generator

30 psig (207 kPa)

Provides flow of a cc/min to ozone generator

rox. 500

rox. 1000

Sample

Pressure Gauge Setting

4 psig (27.6 kPa)

Provides flow of approx. 60 cc/min to reaction chamber

1.5 psig (10.3 kPa)

Provides flow of approx. 20 cc/min to reaction chamber

2. Upscale Calibration. a. Set PPM RANGE Switch at the position appropriate to the particular span gas. b. Supply upscale standard gas of accurately known NO/NOx content to rear

panel SAMPLE inlet. c. Place MODE Switch at NO if nitric oxide span gas is used. d. Adjust SPAN Control so that reading on meter or recorder is equal to the known

parts-per-million concentration of NO or NOx in the span gas. In operation at

NOx levels in the range of 2500 to 10000 parts-per-million, the correct reading

may not be obtainable, initially, by adjustment of the SPAN Control. The cause

is that the reduced sample flow required for linearity results in lowered

sensitivity and slower response. To compensate for these effects, make the

electronic adjustments of Steps (e) and (f) below. e. If necessary, increase sensitivity by raising photomultiplier voltage per Section

6.1, Step 5.

f. To reduce observed noise, select SLOW position of Response Time Selector

Switch SW2, Figure 3-1. g. When correct upscale reading is obtained, loc k SPAN Control knob.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

3-3

TARTUP

Calibration is now complete. Before Placing analyzer in operation, however, measure efficiency of the NO2 to NO converter per Section 3.3.

FAST SLOW

10 100 MV REC

R22

1 V OUTPUT

INPUT

RESPONSE

R34

CALIB

R33 CALIB

R31 CALIB

R32 CALIB

RESPONSE TIME SWITCH

R16

IGURE

3-1. A

MPLIFIER BOARD ADJUSTMENTS

3.3 MEASURING EFFICIENCY OF NO2 TO NO CONVERTER AND ADJUSTING TEMPERATURE SETPOINT

It is the responsibility of the user to measure efficiency of the NO2 to NO converter during initial startup and thereafter at intervals appropriate to the application, normally once a month.

The reactant material used in the converter provides the optimum combination of high conversion efficiency and low ammonia interference. Unlike most competitive analyzers, the Model 951A utilizes a reactant material that gradually becomes more efficient at a given temperature , and thus after a period of use may permit operation with a lower temperature setpoint than that required initially.

Conversion efficiency in the Model 951A is typically 95% to 98% +, considerably above the 90% minimum accepted by the EPA. Refer to 40 CFR 60, App. A, Method 20, Section 5.6.

3.3.1 T

EST SETUP FOR MEASUREMENT OF CONVERSION EFFICIENCY

3-4

A typical setup for measurement of conversion efficiency is shown in Figure 3-2A. The test setup includes:

1. A cylinder of nitric oxide standard gas consisting of NO in N2. The concentration of NO in the standard gas should be about the fullscale value of the range under test. The test sample supplied to the analyzer should contain a concentration of NO

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

TARTUP

comparable to that in the samples that are to be analyzed. Alternately, a higher concentration NO standard may be used if the test setup includes provision for diluting it appropriately with zero air. Suitable standard gases are available from various suppliers. Stainless steel cylinders are commonly used, but specially treated aluminum is preferre d for low parts-per-million NO samples.

2. An ozone generator utilizing an ultraviolet lamp, not a corona discharge. A corona discharge ozone generator is undesirable as it may produce oxygen atoms, which can then combine with atmospheric nitrogen to form NO. The result can be an erroneously high value for the measured conversion efficiency.

3.3.2 T

EST PROCEDURE

1. Measure converter temperature by connecting a millivolt meter to terminals 5 (+) and 6 (-) on TB9. Within the analyzer, these terminals are connected to a Type J thermocouple. Note present reading as a reference for comparison with subsequent measurements. The optimum temperature differs from one analyzer to another. but typically is in the range of 660oF to 750oF (350oC to 400oC).

2. Turn front panel CONVERTER ADJUST one turn counterclockwise, to lower temperature setpoint slightly from the original factory setting. Wait 15 minutes for temperature equilibration, then proceed to Step 3.

3. Refer to Figure 3-2. Connect the Model 958 NO2 Converter Efficiency Tester to the Model 951A, and use the following procedure, adapted from 40 CFR 60, to determine the values to be used in Equation (A):

a. Attach the NO/N2 supply at C2. the air supply at C1, and the analyzer inlet

connection at C3.

b. With the variable transformer off, place Model 951A in NO mode and close

valve MV1. Open valve MV2 until Model 951A SAMPLE Pressure Gauge reaches operating pressure and BYPASS Flowmeter indicates some bypass flow. Wait until stable readings are obtained at analyzer. Zero and span the analyzer output to indicate the value of the NO concentration being used. This value should be approximately 80% of fullscale. Record this concentration.

c. Open valve MV1 (air supply metering valve) and adjust to blend enough air to

lower the NO concentration (ii) about 10%. Record this concentration.

d. Turn on the ozonator and increase its supply voltage until the NO concentration

of (iii) is reduced to about 20 percent of (ii). NO2 is now being formed from the NO + O3 reaction. There must always be at least 10 percent un-reacted NO at this point. Record this concentration.

e. W hen a stable reading has been obtained from (iv), place Model 951A in NOx

mode. It will now indicate the total NOx concentration. Record this concentration.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

3-5

TARTUP

f. Turn off the ozonator and allow the analyzer reading to stabilize. This reading is

the total NOx concentration of the dilute NO span ga s used at step (iii). Record this concentration.

f. Close valve MV1. The NO concentration should be equal to or greater than the

reading of (ii). Indicating whether the NO contains any NO2.

g. Calculate the efficiency of the NO converter by substituting the concentrations

obtained during the test into the following equation.

Equation (A)

% Efficiency = 1 + X 100

v-vi iii-iv

In the example of Figure 3-2B,

% Efficiency = 1 + X 100% = 92%

85-90 80-20

Efficiency checks should be made on each analyzer range, using an NO span gas concentration appropriate to the instrument range.

Note

In the initial measurement, following lowering of the temperature setpoint in Step 2, the efficiency will normally be less than 92%.

4. Turn CONVERTER ADJUST one quarter turn clockwise, thus raising temperature setpoint slightly. Wait 15 minutes for temperature equilibration. Again measure conversion efficiency per Step 3; it should be somewhat improved.

3-6

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

A. TYP ICA L TES T S E TUP

FLOWMETER FM2

METERING VALVE MV2

115 VAC

OFF

VARIABLE TRANSFORMER

CONNECTOR C3

OZONATOR UTILIZING ULTRAVIOLET LAMP

FLOWMETER FM1

TO SAMPLE INLET OF MODEL 951A

FLOW APPROXIMATELY 3 LITERS PER MINUTE

TARTUP

CONNECTOR C2

NO IN N2 BA CKGROUN D

B. TYPICAL TEST RESULTS

NO in

AIR ADDED

c-d

OZONATOR OFF

OZONATOR ON

METERING VALVE MV1

CONNECTOR C2

CONNECTOR C1

a-b

% Efficiency = 100

IGURE

556383-Y Rosemount Analytical July 2000

3-2. M

EASURING EFFICIENCY OF

TO NO MODE

NO C

ONVERTER

Model 951A NO/NOx Analyzer

3-7

TARTUP

5. Repeat Step 4 until either (a) 95% efficiency is attained, or (b) the final one quarter turn clockwise adjustment yields an increase in efficiency of less than 1%. Then proceed to Step 5.

6. Turn CONVERTER ADJUST one-eighth turn counterclockwise, thus lowering temperature setpoint very slightly. Converter temperature is now set at a point on the front edge of the plateau on the efficiency-vs.-temperature curve, Figure 3-3. This setting should provide the optimum combination of high conversion efficiency and low ammonia interference. Wait about fifteen minutes for temperature equilibration, then again measure converter temperature as in Step 1. Compare present temperature with original value. Normally, converter temperature should be in the range of 660oF to 750oF (350oC to 400oC).

Note Converter temperature is not a direct measure or conversion efficiency.

Temperature measurement is for reference purposes only.

IGURE

3-3. C

About

95%

Final 1/4 Turn Clockwise adjustment of CONVERTER ADJUST

Final 1/8-Turn

Converter Efficiency

Converter Temperature

ONVERSION EFFICIENCY AS A FUNCTION OF CONVERTER

EMPERATURE

Counterclockwise Adjust men t of CONVERTER ADJUST

3-8

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

TARTUP

3.3.3 S

UBNORMAL CONVERSION EFFICIENCY

If a measured conversion efficiency of 95% is unobtainable within the normal temperature range, the most probable cause is depletion of the catalytic material within the converter. However, before concluding that the converter is defective, make sure that the conversion efficiency measurement is accurate. Even though the measured eff iciency is less th an 95%, the actual efficiency may be somewhat higher. An apparent subnormal efficiency can be due to a problem external to the analyzer, located either within the test setup, or between it and the analyzer. Check for the following:

1. Leakage.

2. Loss of NO2 between test setup and analyzer. Such loss can occur by reaction with a rubber diaphragm in a pressure regulator or flow controller. Stainless steel diaphragms are preferred. Loss can also occur during passage through filter media.

3.3.4 R

EPLACEMENT OF CONVERTER

If it is determined that the subnormal conversion efficiency is real, and not due to measurement error introduced by the test setup, the converter must be replaced per Section 6.2.3. The usual cause of converter failure is destruction of a large part of the catalytic material by excessive heat, due either to excessively high temperature setpoint or failure of the converter temperature control circuit.

3.3.5 C

APILLARIES

Replacement capillaries shou ld be installed finge r-tight. Use of a wrench can constrict capillaries, changing flow rate.

3.3.6 TEA S

CRUBBER

The TEA Scrubber accessory (PN 635741) can be used to remove residual NO2 from the NO cylinders. Use of this accessory allows a true calibration of the analyzer.

White crystal deposits on the windows of the reaction chamber and plugging of capillaries and vent are usually due to sample contaminates reacting with the high ozone levels. To eliminate the contaminates, the sampling system should be reworked or a preventive maintenance program developed (if dropout is not excessive). Another source of crystalline formation is contaminated air.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

3-9

TARTUP

OTES

3-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

PERATION

4.1 ROUTINE OPERATION

After calibrating analyzer per Section 3.2, supply sample to SAMPLE inlet. Place MODE Switch in NO or NOx position, depending on the desired determination. Set PPM RANGE Switch in appropriate position. The instrument will now continuously analyze the sample stream.

The Model 951A is designed for continuous operation. Normally, it is never turned off except for servicing or for a prolonged shutdown. However, if the instrument is to remain idle for an extended period with power on, the recommended practice is to leave the MODE Switch in NO position to de-energize the NO/NOx Mode Switching Solenoid Valve.

4.2 RECOMMENDED CALIBRATION FREQUENCY

After initial startup, or startup following a shutdown, the analyzer requires about one hour for stabilization before it is ready for calibration. Maximum permissible interval between calibrations depends on the analytical accuracy required, and therefore cannot be specified. It is recommended that initially the instrument be calibrated at least once every eight hours, and that this practice be continued until experience or requirements indicate that some other interval is more appropriate.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

4-1

PERATION

OTES

4-2

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

5.1 PRINCIPLES OF OPERATION

HEORY

5.1.1 N

5.1.2 NOX D

ITRIC OXIDE DETERMINATION BY CHEMILUMINESCENCE METHOD

The chemiluminescence method for detection of nitric oxide (NO) is based on its reaction with ozone (O3) to produce nitrogen dioxide (NO2) and oxygen (O2). Some of the nitrogen dioxide molecules thus produced are initially in an electronically excited state (NO2*). These revert immediately to the ground state, with emission of photons. The reactions involved are:

NO + O3 → NO2* + O NO2* → NO2 + hv

where

h = Planck's constant v = frequency, Hz

As NO and O3 mix in the reaction chamber, the chemiluminescence reaction produces light emission that is directly proportional to the concentration of NO. This emission is measured by a photomultiplier tube and associated electronic circuitry. Refer to Section 5.3.

ETERMINATION

The NOx determination is identical to the NO determination described in Section 5.1.1 except that, prior to entry into the reaction chamber, the sample is routed through a converter where the NO2 component is converted into NO. The reaction is:

2NO2 → 2NO + O

Instrument response is proportional to total NO in the converted sample, that is, to the sum of the NO originally present in the sample plus the NO resulting from conversion of NO2. This sum of NO and NO2 is commonly termed NOx, i.e., ([NOx] = [NO] + [NO2]).

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

5-1

HEORY

5.1.3 O

ZONE GENERATION

Ozone for the chemiluminescence reaction is produced in a flow chamber where a stream of air or oxygen from an external cylinder is exposed to ultraviolet radiation from a source lamp. The reaction is:

hv 3O2 → 2O

5.2 ANALYZER FLOW SYSTEM

The analyzer flow system is shown schematically in Figure 5-1 and pictorially in Figure 6-1. Its basic function is to deliver regulated flows of sample or calibration gas and ozonized air or oxygen to the reaction chamber. The discharge from the reaction chamber exits the analyzer via the EXHAUST outlet.

OZONE Pressure Gauge

Restrictor

Bypass Valve

Air or

Oxygen

AIR Inlet

SAMPLE

Inlet

OZONE

Pressure

Regulator

Flow

Controller

(option)

Sample

Pump

(option)

Ozone

Generator

Converter

Flow

Balance

Valve

End-On Photomultiplier

Ozonized Air or Oxygen for

Chemiluminescent Reaction

Reaction Chamber

NO/NOx Mode

Switching

Solenoid Valve

Sample Pressure Gauge

Sample

Capillary

Pump Capillary

Window

Tube

Signal to Electronic Circuitry

Bleed Capillary

Bypass Flowmeter

Sample Backpressure Regulator

IGURE

5.2.1 F

5-1. S

LOW OF SAMPLE OR STANDARD GAS TO REACTION CHAMBER

CHEMATIC FLOW DIAGRAM OF MODEL

951A

Suitably pressurized sample or standard gas is supplied to the rear panel SAMPLE inlet.

Within the analyzer, flow rate of the selected gas into the reaction chamber is controlled by a back-pressure regulator. It provides an adjustable, controlled pressure on the upstream side, where gas is supplied to the calibrated, flow-limiting sample

Exhaust

5-2

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

HEORY

capillary. The regulator is adjusted for appropriate reading on the SAMPLE Pressure Gauge. For operation at NOx levels below 2,500 parts-per-million, correct setting on the SAMPLE Pressure Gauge is 4 psig (27.6 kPa), resulting in a flow of approximately 60 cc/min to the reaction chamber. For operation at NOx levels in the range of 2,500 to 10,000 parts-per-millio n, se ttin g on SAMP LE Pressure Gau ge shou ld b e 1.5 p sig (10 .3 kPa), resulting in a flow of approximately 20 cc/min to the reaction chamber.

Gas in excess of the flow required for the reaction chamber is discharged through the BYPASS Flowmeter and out the BYPASS outlet. Bypass flow should be two liters per minute to ensure optimum functioning of the SAMPLE Pressure Regulator and rapid system response. Total flow of sample or standard gas into the SAMPLE inlet is adjusted by means of the BYPASS Needle Valve (or optional flow controller). Excessive changes, on the order of ±5 psig (±34.5 kPa), in the pressure of the sample or standard gas will affect the bypass flow rate and can affect accuracy.

5.2.2 F

LOW OF AIR OR OXYGEN

WARNING: OZONE HAZARD

To prevent such damage, verify that the front panel ozone ON/OFF switch is turned off if flow of feed gas to the air inlet is terminated.

Suitably pressurized air or oxygen from an external cylinder is supplied to the rear panel AIR inlet. Immediately downstream from the inlet, a regulator and associated gauge provide pressure adjustment and indication for air or oxygen. Proper pressure setting. and the corresponding flow to the ozone generator, will depend on sample NOx level. Refer to Table 3-1.

1. For operation at NOx levels below 1,000 parts-per-million, correct air pressure setting on OZONE Pressure Gauge is 20 psig (138 kPa), resulting in a flow of approximately 500 cc/min of air to the ozone generator.

2. For operation at NOx levels in the range of 1,000 to 2,500 parts-per-million, air pressure setting on OZONE Pressure Gauge should be 30 psig (207 kPa),

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

5-3

HEORY

resulting in a flow of approximately 1 liter per minute of air to the ozone generator.

3. For operation at NOx levels in the range of 2,500 to 10,000 parts-per-million, oxygen pressure setting on OZONE Pressure Gauge should be 30 psig (207 kPa), resulting in a flow of approximately 1 liter per minute of oxygen to the ozone generator.

Within the ozone generator, a portion of the oxygen in the stream is converted into

ozone by exposure to ultraviolet radiation from a lamp source. From the generator, the flow passes into the reaction chamber for use in the chemiluminescence reaction.

5.2.3 F

LOW SYSTEM OPERATING MODES

Downstream from the BYPASS Needle Valve, the sample or standard gas flows through either the FLOW BALANCE Needle Valve or the NO2 to NO converter, depending on the status of NO/NOx Mode Switching Solenoid Valve K3. Status of this valve depends on whether the front panel MODE Switch is in NO or NOx position.

Operation for NO and NOx determination is as follows:

NO D

ETERMINATION

Sample or standard gas is supplied to the rear panel SAMPLE inlet, passes in turn through the BYPASS Needle Valve, NO/NOx Mode Switching Solenoid Valve K3, the sample capillary, and on to the reaction chamber. Since the NO2 to NO converter is bypassed, any NO2 component originally present in the sample remains in the NO form and does not contribute to the output signal. (During startup, the FLOW BALANCE Needle Valve is adjusted to equalize flow rated for NO and NOx flow modes.)

NOX D

ETERMINATION

Sample or standard gas supplied to the rear panel SAMPLE inlet passes in turn through the BYPASS Needle Valve, the NO2 to NO converter, the solenoid valve, the sample capillary and on to the reaction chamber. With the sample now routed through the converter, the NO2 component is converted into NO prior to entry into the reaction chamber, and thus will contribute to the output signal.

5-4

During startup, the FLOW BALANCE Needle Valve is adjusted to equalize flow rates for NO and NOx flow modes. Criterion for correct adjustment is that an NO2 free nitric oxide standard gas should give equal readings of parts-per-million for NO and NOx modes.

An alternate method of checking flow balance, usable if NO2 free standard gas is unavailable, is to verify that the reading on the SAMPLE Pressure Gauge is the same for NO and NOx modes. If not, adjust FLOW BALANCE Needle Valve as required.

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

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5.2.4 C

ONVERTER BLEED FLOW

Even in converter bypass condition (i.e., de-energized state of the solenoid valve), a flow of approximately 100 cc/min of sample or standard gas passes continuously through the converter and the bleed capillary. This bleed flow pro vides f aster respo nse and ensures that the sample within the converter is current. Bleed flow need not be precisely 100 cc/min. However, an excessively low bleed flow will result in impaired response. Conversely, use of excessively high bleed flow may result in failure to obtain the required flow of 60 cc/min for the reaction chamber. Thus the nominal value of 100 cc/min represents a compromise between response time requirements and sample supply.

5.3 ELECTRONIC CIRCUITRY

Photons emitted during the chemiluminescence reaction (Section 5.1.1) impinge on the end-on photomultiplier tube, generating a signal current of approximately 3 x 10 amperes per parts-per-million concentration of NO in the reaction chamber. This current is measured by an electrometer amplifier.

A functional diagram of the electronic signal circuitry is shown in Figure 5-2. For a more detailed presentation of the signal circuitry, plus control circuitry for actuation of NO/NOx Mode Switching Solenoid Valve, etc., refer to the overall schematic and pictorial diagrams in the rear of this manual, respectively. Individual circuit boards plug into the Interconnect Board, shown in Figure 7-2.

-10

+15

PHOTOMULTIPLIER

TUBE

REACTION

CHAMBER

ZERO AND SPAN POTENTIOMETERS LOCATED ON FRONT PANEL. R6, R16, R22, R31, R32, R33 AND R34 LOCATED ON AMPLIFIER BOARD AND

ACCESSIBLE THROUGH HOLES IN AMPLIFIER BOARD COVER (SEE FIGURE 6-1).

IGURE

5-2. F

HIGH

VOLTAGE

POWER SUPPLY

UNCTIONAL SCHEMATIC DIAGRAM OF ELECTRONIC SIGNAL CIRCUITRY

AR1

TP1

R34

R33

R32

R31

PPM RANGE

TP2

R16

AR2

S P A

R22

100mV

10mV

+ REC

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

5-5

HEORY

As shown in Figure 5-2, the anode of the photomultiplier tube is connected to the inverting input of AR1, and integrated circuit MOSFET amplifier with extremely high input impedance to minimize loading effects, and comparatively low output impedance to match the following stage. The signal from AR1 is directed to integrated circuit amplifier AR2 for addition al gain.

The front panel ZERO Contro l applies an adjustable zero-biasi ng signal to the input of AR1, to permit setting the zero point on the meter scale or recorder chart.

For adjustment of overall sensitivity, the current measuring circuitry utilizes two front panel controls:

1. The PPM RANGE Switch, associated with AR1, provides a choice of seven fullscale sensitivities, obtained by a combination of high/low feedback selection and output attenuation. Potentiometers R31, R32, R33 and R34 are adjustable to provide inter-range correlation of exactly adjusted integral multiples. Refer to Section 6.1, Step 3.

2. The SPAN Control, associated with AR2, provides continuously variable gain through feedback adjustment. A voltage divider network associated with AR2 provides a selectable output for a potentiometric recorder.

The following sections describe electronic circuitry of individual circuit boards.

5.3.1 A

MPLIFIER BOARD AND ASSOCIATED CIRCUITRY

The Amplifier Board provides two stages of amplification utilizing integrated circuit amplifiers AR1 and AR2.

UNCTIONS ASSOCIATED WITH

AR1:

AR1 Zero Adjust Potentiometer R6: This screwdriver adjusted trimming potentiometer, accessible through a hole in the amplifier cover, is used to eliminate voltage offset with AR1. When input signal is zero, output signal also should be zero. Refer to Section 6.1 for proper adjustment procedure.

Front Panel Zero Control: This control applies an adjustable zero-biasing sign al to the input of AR1. to permit setting the zero point on the meter scale or recorder chart. The adjustment compensates for a residual amplifier input signal resulting from a combination of background signal and photomultiplier dark current.

Front Panel PPM RANGE: Switch and Associated Resistor Network. The PPM RANGE Switch controls sensitivity by a combination of two methods:

5-6

Selection of high or low feedback resistance via a transistor switching circuit. Potentiometer R34, adjustable by insertion of a screwdriver through a hole in the amplifier cover, permits establishing exactly the correct ratio between the high and low feedback resistances.

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

HEORY

Output attenuation via resistors associated with relays U1, U2 and U3 on the amplifier board. Potentiometers R31, R32 and R33, adjustable by insertion of a screwdriver through the corresponding holes in the amplifier cover, permit inter-range correlation of exactly adjusted integral multiples.

UNCTIONS ASSOCIATED WITH

AR2:

AR2 Zero Adjust Potentiometer R16: This screwdriver adjusted trimming potentiometer, accessible through a hole in the amplifier cover, is used to eliminate voltage offset with AR2.

Front Panel SPAN Control: Provides continuously variable adjustment of AR2 gain. Response Time Selection Switch SW2: Provides choice of fast or slow response:

With switch in FAST position, electronic response time (for 0 to 90% of fullscale) is approximately one second for all ranges except 10 ppm, approximately three seconds for 10 ppm range.

For such applications as monitoring of stack sources, where slow response is desired, switch is placed in SLOW position. Electronic response time (0 to 90% of fullscale) is then approximately 10 seconds for all ranges. Closure of the switch connects capacitors C7 and C8 across resistor R17, thus increasing the RC time constant.

Recorder Output Selection Switch SW1: The desired recorder output is obtained by closing the corresponding contact on Switch SW1, thus selecting the appropriate tap on a voltage divider connected across the output of AR2.

Meter Span Adjustment Potentiometer R22: Potentiometer R22, adjustable by insertion of a screwdriver through the hole in the amplifier cover, permits adjusting the fullscale span of the meter so that meter readout agrees with recorder readout.

5.3.2 V

ALVE CONTROL BOARD

IRCUITRY

RONT PANEL MODE SWITCH AND ASSOCIATED

, F

As shown in Drawings 649834 and 649835, actuation of NO/NOx Switching Solenoid Valve K3, associated with the NO2 to NO converter, is controlled by front panel MODE Switch SW2 via the valve driver circuit on the Valve Control Board. With MODE Switch in NO position, the solenoid valve is de-energized, placing the converter in bypass condition. With switch in NOx position, the solenoid valve is energized, placing the converter in in-line condition.

Drawing 656313 shows internal circuitry of the Valve Control Board. The valve driver circuit consists of a single-pole, single-throw relay and associated TRIAC element. The relay is used only to switch the gate current for the TRIAC; therefore, power carried by the relay contacts is very small.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

5-7

HEORY

Each relay is connected to AC neutral while the associated TRIAC is connected to 115 VAC. When the relay closes, in response to closure of the associated contacts on the MODE Switch, gate current flows through the relay contacts and causes the TRIAC to fire. Resistance of the TRIAC becomes very small, causing application of 115 VAC across the solenoid. When the relay contacts open, the gate current is interrupted and the TRIAC stops conducting. Thus the relay controls the power applied to the solenoid.

5.3.3 ±±±±15 V

OLT POWER SUPPLY

The ±15 Volt Power Supply provides power for the various circuits. As shown in Drawing 619710, power transformer T1 has three secondarys that are used as follows:

38 VAC center-tapped secondary - Powers both 15 volt supplies through diode bridge CR1 and filter capacitors C1 and C4.

The adjustable positive regulator, VR1, is set by voltage divider R1, R2 and R3; and its output is applied to pin A of the circuit board and to test point TP1. Potentiometer R2 should be adjusted to +15.5 VDC ±50 mVDC.

The negative DC, regulated by VR2, is applied to pin D of the circuit board. The center tap is the common reference for both the +15 and the -15 volt supplies and

is applied to pin R of the circuit board and test point TP2. Both outputs are used for individual amplifiers on the various circuit boards and for the

zero-biasing circuit associated with the front panel ZERO Control (Section 5.3.1).

90 V secondary - Not used in this instrument.

9.5 VAC secondary - Drives a +5 V supply not used in this instrument.

5.3.4 H

As shown in Drawings 649834 and 649835, DC high voltage for the photomultiplier tube is provided by the 630922 High Voltage Power Supply. It operates from the ±15 Volt Power Supply (Section 5.3.3).

Drawings 652423 and 654348 shows internal circuitry of the high voltage power supply. It consists of a voltage regulator circuit utilizing non-inverting operational amplifier AR1 and a flux-switching DC to AC converter. Potentiometer R4 provides an adjustment range of approximately -650 V to -2100 V for the regulated DC voltage supplied to the photomultiplier. Nominal setting is for -900 V; however, during factory checkout of the individual instrument, R4 is adjusted as required for overall system sensitivity. If necessary, R4 is readjusted per Section 6.1, Step 5.

5-8

IGH VOLTAGE POWER SUPPLY

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

HEORY

5.3.5 C

ONVERTER TEMPERATURE CONTROL BOARD AND ASSOCIATED ELEMENTS

The temperature control circuit for the NO2 to NO converter consists of:

Temperature sensor R3, a platinum resistance element m ounted in the converter. Converter Temperature Control Board. CONVERTER ADJUST potentiometer R6 mounted on the front panel, Figure 2-2. Resistive heating element within a lace-on jacket.

During startup, temperature of the platinum sensor is initially below the setpoint selected with the CONVERTER ADJUST potentiometer. Controller now switches to “on” condition, and applies power to the header via TRIAC element Q5. The controller remains in “on” condition until temperature of the platinum sensor has risen sufficiently to come within the range of the proportional band of the controller. The controller then switches alternately off and on during a two-second time base. to maintain the temperature of the heater at the setpoint.

Clockwise rotation of the CONVERTER ADJUST raises the setpoint; counterclockwise rotation lowers it. Setpoint adjustment is explained in Section 3.3.

Note When installing or reinstalling the lace-on healer jacket on the converter, make

sure that the yellow fiberglass sleeve on the temperature sensor leads is exposed and is not enclosed within the jacket. Otherwise, the insulation may burn off the sensor leads, causing short-circuiting of the sensor and temperature runaway or the converter heater.

ONVERTER TEMPERATURE READOUT THERMOCOUPLE

The Converter has an associated Type J thermocouple to permit temperature monitoring. The thermocouple connections, i.e., terminals 5(+) and 6(-) on TB9, are used to measure converter temperature in the range of 660oF to 750oF (350oC to 400oC). The optimum temperature differs from one analyzer to another. Refer to Section 3.3.

Note Converter temperature is not a direct measure of conversion efficiency.

Temperature measurement is for reference purposes only. An exact determination of conversion efficiency is performed by the procedure given in section 3.3.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

5-9

HEORY

5.3.6 F

AN CONTROL CIRCUIT

The fans in current production instruments run continuously. In older instruments, the fan control circuit consists of thermistor R4, TRIAC switching circuit and blower fan B. When internal temperature of the analyzer reaches approximately 100oF (38oC), the fan is turned on.

5.3.7 R

EMOTE OPERATION OPTION

The Remote Operation Option, Figure 2-5, consists of a Plug-In Adapter Board with attached harness that terminates on a rear panel plate.

The adapter board has two two-position slide switches: the MAN/AUTO MODE Switch and the MAN/AUTO RANGE Switch.

The MAN/AUTO MODE Switch provides the choice of local or remote control of the NO/NOx Mode Switching Solenoid Valve, associated with the NO2 to NO converter. With switch at MAN, the function is under control of the front panel MODE Switch (Section 5.3.2). With switch at AUTO, the front panel MODE Switch is disabled; the function is then remotely controlled, by either the operator or a computer, via contact-closure signals applied to terminals on TB5.

The MAN/AUTO RANGE Switch provides the choice of local or remote selection of operating range. With switch at MAN, range selection is under control of the front panel PPM RANGE Switch. With switch at AUTO, the front panel PPM RANGE Switch is disabled; range selection is remotely controlled by either the operator or a computer, via contact-closure signals applied to terminals on TB6.

5.3.8 R

ANGE

I.D. O

PTION

The Range I.D. Option provides contact closure signals that permit a computer or other external device to identify the position selected on the front panel PPM Switch. This cable is connected to PPM Switch SW1 and extends to connector J10 mounted on the rear of the case.

5-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

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.

WARNING: ULTRAVIOLET LIGHT HAZARD

UV light from the ozone generator can cause permanent eye damage. DO NOT LOOK DIRECTLY AT THE UV SOURCE IN THE OZONE GENERATOR. Use of UV filtering glasses is recommended.

WARNING: LIGHT EXPOSURE

The photomultiplier tube must not be exposed to ambient light. Unless appropriate precautions are observed, light can strike the tube upon removal of fittings from the reaction chamber.

6.1 SYSTEM CHECKS AND ADJUSTMENTS

The following procedures may be used to determine the cause of unsatisfactory instrument performance, or to make adjustments following replacement of components. If a recorder is available, use it for maximum convenience and accuracy in the various tests.

ETER MECHANICAL ZERO

With electrical power removed from the analyzer, connect a shorting jumper across the terminals of the front panel readout meter. Meter should read zero; if not, adjust screw at rear of meter as required. Remove jumper.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-1

ERVICE AND MAINTENANCE

MPLIFIER ZERO ADJUSTMENTS

Refer to Figure 6-1 for location of Amplifier Board components noted in the following procedure.

1. Open front panel to turn off high voltage; set SPAN Control at 1000; set ZERO Control at 1000. Then perform the following checks and adjustments:

2. With PPM RANGE Switch at 250, obtain zero reading on meter or recorder by screwdriver adjustment of R16, accessible through hole in cover of amplifier board.

3. With PPM RANGE Switch at 1000, obtain reading of 0 (±1 division) on meter or recorder by screwdriver adjustment of R6, accessible through hole in cover of amplifier board.

4. Repeat Step a. If the specified zero readings are unobtainable by adjustment of the corresponding potentiometers, replace amplifier board.

NTER-RANGE ATTENUATION CORRELATION ADJUSTMENTS

Refer to Figure 6-1 for location of Amplifier Board components noted in the following procedure.

1. During the following adjustments, observe the analyzer output on a digital voltmeter or strip-chart recorder. If neither is available, use the front panel meter. Perform the following adjustments:

2. Supply 10 parts-per-million standard to analyzer. Set PPM RANGE Switch at 10. Obtain fullscale reading by adjustment of front panel SPAN Control.

3. Move PPM RANGE Switch to 250. Obtain reading of 4% of fullscale by screwdriver adjustment of R33, accessible through hole in cover of amplifier board.

4. Move PPM RANGE Switch to 25. Obtain reading of 40% of fullscale by screwdriver adjustment of R31, accessible through hole in cover of amplifier board.

5. Move PPM RANGE Switch to 100. Obtain reading of 10% of fullscale by screwdriver adjustment of R32, accessible through hole in cover of amplifier board.

6. Supply 100 parts-per-million standard to analyzer. Adjust front panel SPAN Control for fullscale reading.

7. Move PPM RANGE Switch to 1000. Obtain reading of 10% of fullscale by screwdriver adjustment of R34, accessible through hole in cover of amplifier board.

ETER FULLSCALE SPAN ADJUSTMENT

If a recorder is used, and has been properly zeroed, it should agree with the meter reading. If not, obtain agreement by screwdriver adjustment of R22, accessible through hole in cover of amplifier board (Figure 6-1). If agreement cannot be obtained, check recorder. If recorder is functioning properly, replace amplifier board.

6-2

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

10 100 MV REC

R22

5 1 V OUTPUT

FAST SLOW

RESPONSE

R34

CALIB

INPUT

R33 CALIB

R31 CALIB

R32 CALIB

R16

ERVICE AND MAINTENANCE

IGURE

6-1. A

VERALL SENSITIVITY

MPLIFIER BOARD

Principal factors that determine overall sensitivity of the analyzer are: (a) sample flow rate to the reaction chamber, and (b) sensitivity of the photomultiplier tube. If specified fullscale readings are unobtainable by adjustment of the SPAN Control, sensitivity is subnormal. The cause of the reduced sensitivity may be in either the flow system (Section 6.2) or the electronic circuitry (Section 6.3).

If either the High Voltage Board or the Phototube/Reaction Chamber Assembly has been replaced, a readjustment of R4 on the High Voltage Board will probably be required to obtain the correct overall sensitivity. Turn the adjustment in the appropriate direction: clockwise to increase photomultiplier high voltage and therefore sensitivity; or, counterclockwise to decrease voltage and sensitivity. Adjustment range is approximately -650 volts to -2100 volts for the regulated DC voltage applied to the photomultiplier. Nominal setting is for -1100 volts; however, the adjustment should be set as required for overall system sensitivity.

ZONE OUTPUT

Maximum concentration of NO or NOx which the analyzer will measure with linearity depends on both the ozone generator output and the sample flow rate. If the analyzer seems to be ozone limited at high concentrations of NO or NOx, possible causes are: incorrect sample flow rate, incorrect flow rate through ozone generator, malfunction in ozone generator or associated transformer.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-3

ERVICE AND MAINTENANCE

WARNING: TOXIC GAS

Use extreme caution in troubleshooting ozone generator. Ozone is toxic.

CAUTION: OZONE DAMAGE

To prevent such damage, verify that the front panel ozone ON/OFF switch is turned off if flow of feed gas to the air inlet is terminated.

ACKGROUND CURRENT

With zero air supplied to rear panel SAMPLE inlet, and MODE Switch at either NO or NOx, excessive background current is evidenced by inability to obtain zero meter reading by adjustment of the ZERO Control. If background current is excessive, the cause must be found and corrected. The fault may be in either the electronic circuitry or the sample flow system.

First, establish proper performance of the electronic circuitry. Turn off high voltage by opening door. Turn on analyzer power. Verify that ZERO Control and amplifier are functioning properly. Close door and check for the following:

1. Excessive photomultiplier dark current. To check, shut off all flow to the ozone generator. Supply cylinder air to rear panel SAMPLE inlet. With MODE switch at NO, note response on meter or recorder. If background is still excessive, possible causes are: (1) leakage of ambient light to photomultiplier tube, or (2) defective photomultiplier tube.

2. Contamination of reaction chamber or sample flow system. Refer to Sections

6.2.1, 6.2.2 and 6.2.4

6-4

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

NO C

ONVERTER TEMPERATURE ADJUSTMENT

Use procedure of Section 3.3 The FLOW BALANCE Control must now be adjusted to equalize pressure drops for

the NO and NOx legs of the internal flow system. In the usual method, NO2 free nitric oxide standard gas is supplied to the analyzer and the FLOW BALANCE Control is adjusted for equal reading of parts-per-million for the NO and NOx modes, as explained in Step 9.

An alternate method of flow balance, useable if NO2 free nitric oxide standard gas is unavailable consists of checking SAMPLE pressure reading for NO and NOx modes, as described in Step 10.

LOW BALANCE USING FRONT PANEL METER INDICATION WITH

ITRIC OXIDE STANDARD GAS

FREE

1. Supply to the SAMPLE inlet a suitable NO2 free nitric oxide span gas, for example 2500 parts-per-million NO. And NO span gas may be used, since balance is independent of concentration. However, it is important that the span gas be entirely free of NO2; otherwise, the supposed flow balance achieved will be erroneous. A NO span gas known to be free of NO2 can be purchased as a certified standard gas. Set SAMPLE Pressure Regulator so that SAMPLE Pressure Gauge indicated the value appropriate to the desired operating range. Refer to Figure 3-3. Set BYPASS Needle Valve for reading of 2 liters per minute on BYPASS Flowmeter.

2. Supply to the AIR inlet suitable air or oxygen, depending on the operating range. Refer to Section 2.3. Adjust OZONE Pressure Regulator so that OZONE Pressure Gauge indicates the value appropriate to the desired operating range. Refer to Figure 3-3.

3. Set MODE Switch at NO. Leave ZERO Control at previous setting. Turn PPM RANGE Switch to a setting appropriate to the nitric oxide content of the particular span gas. Adjust SPAN Control for reading of approximately 90% on meter or recorder.

4. Move MODE Switch from NO to NOx; compare meter or recorder readings for the two modes. The NOx reading should be equal to the NO reading. If the readings are within acceptable agreement, the flows are properly balanced.

If the readings for the two modes are not in acceptable agreement, adjust the front

panel FLOW BALANCE Control as required.

LTERNATE FLOW BALANCE METHOD

A NO

AND

NOX M

ODES

SING SAMPLE PRESSURE READING FOR

, U

If NO2 free nitric oxide standard gas is unavailable, verify that reading on SAMPLE Pressure Gauge is the same for NO and NOx modes. If not, adjust FLOW BALANCE Needle Valve as required.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-5

ERVICE AND MAINTENANCE

6.2 SERVICING FLOW SYSTEM

To facilitate servicing and testing, the Model 951A has front, rear and top access. Refer to Drawings 649958 and 649842 in the rear of this manual for details of flow

system.

6.2.1 S

AMPLE CAPILLARY

Depending on when the instrument was made, one of two types of capillaries may be present: a) a black tubing with white Teflon inner sleeve, or b) a one-piece black Teflon tubing.

If clogging of sample capillary is suspected, measure flow rate as described below:

1. Turn off instrument power and shut off all gases.

2. Cover and shade the fittings on the reaction chamber with a dark cloth or other light-shielding material. While maintaining the area properly darkened, remove the fitting associated with the sample capilla ry (red-bande d tube) and place a cap o ver the open fitting to prevent entry of stray light.

Note If the opened fitting is inadvertently exposed to ambient light, the instrument will

temporarily give a highly noisy background reading. If so, this condition may be corrected by leaving the instrument on, with high voltage on, for several hours.

3. With instrument power off, supply suitable test gas (dry nitrogen or air) to rear panel SAMPLE inlet.

6-6

4. Connect a flowmeter to open end of sample capillary. Per Table 3-1, adjust SAMPLE Pressure Regulator to normal operating setting, and verify that flowmeter indicates appropriate flow.

If flow is correct, restore analyzer to normal operation. If flow is low, the capillary requires cleaning; proceed with the following steps:

1. On NO/NOx Mode Switching Solenoid Valve K3, remove fitting from port associated with sample capillary.

2. Clean capillary with alcohol, then purge with dry nitrogen for one minute. Reconnect capillary to K3.

3. W ith the photomultiplier still covere d, slowly insert the free end of the capillary into the corresponding fitting on the reaction chambe r. (If capillary is of the two-piece variety, the bare Teflon tube at the end of the capillary must be inserted blindly and rotated until it enters a channeled internal passage, which can be detected by feel. The end of the Teflon tube should not project into the interior of the chamber; it should be slightly below the surface of the inner face. If tube is too long, trim back

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

slightly as required.) P ush the cap illary in unt il it bottoms again st the interna l fittin g, then tighten fitting.

Note After capillary cleaning, instrument readout may be noisy for a short time, but

should then become quiet. However, if bare Teflon tube is improperly inserted in Step 7, noisy readout will persist.

6.2.2 O

ZONE RESTRICTOR AND CAPILLARY

CAUTION: OZONE DAMAGE

To prevent such damage, verify that the front panel ozone ON/OFF switch is turned off if flow of feed gas to the air inlet is terminated.

With instrument power off, supply suitable test gas (dry nitrogen or air) to rear panel AIR inlet. Cover photomultiplier housing with a dark cloth. At the fitting on the reaction chamber, disconnect the ozone tube (yellow banded) and place a cap over the open fitting to prevent entry of ambient light. Connect a flowmeter to open end of ozone tube. Adjust the OZONE Pressure Regulator so that OZONE Pressure Gauge indicates normal operating pressure, as listed in Table 3-1; verify that test flowmeter indicates appropriate flow, as listed in Table 3-1.

Subnormal flow indicates clogging in the flow path that supplies air or oxygen to the ozone generator. This path contains two pressure reducing elements:

1. A Restrictor, consisting of a metal fitting with internal fritted (metal membrane) restrictor, the fitting is upstream from the inlet port of the ozone generator. If the internal restrictor becomes plugged, the Restrictor must be replaced, as it cannot normally be cleaned satisfactorily.

2. A capillary connected from the outlet of the ozone generator to the ozone inlet of the reaction chamber (coded with a yellow dot). This capillary may be cleaned if desired. Remove the ozone capillary by a procedure similar to that given for the

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-7

ERVICE AND MAINTENANCE

sample capillary in Section 6.2.1, observing all cautions cited. Clean ozone capillary by same method used for sample capillary.

Test for Ozone Efficiency

Perform the following steps:

1. Span the instrument with sample at 5 lb.

2. Decrease the pressure in 1 lb. steps. The response should be equal steps.

If the steps are not equal, there is an ozone deficiency. The ozone transformer lamp should be checked.

6.2.3 R

EPLACING

NO C

ONVERTER

Converter replacement is recommended upon failure to achieve a conversion efficiency of 95% durin g the test of Section 3.3

To remove and replace converter, refer to Figure 6-2A. Within the outer lace on jacket heater, the converter tube is wrapped in aluminum foil, with the temperature sensor in contact with the glass converter tube. In removing foil, note sensor and thermocouple position to ensure correct repositioning during reassembly. Assemble sensor to replacement converter, as shown in Figure 6-2B, using new aluminum foil.

Note When installing or reinstalling the lace on heater jacket on the converter, make

sure that the yellow fiberglass sleeve on the temperature sensor leads is exposed and is not enclosed within the jacket. See Figure 6-2C.

6-8

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

Lace-On Heater

Thermocouple

Temperature Sensor

Converter Tube Connector (2)

Tube (2)

B. ATTACHING TEMPERATURE SENSO R TO CO NVERTER TUBEA. EXPLODED VIEW

Temperature Sensor

NOx -to-NO

Converter Tube

Top of Converter Assembly

Thermocouple

NOTE Orient converter tube as shown and install sensor flush with outside edge of tube as shown.

NOTE Sensor leads to be outside heater jacket.

ERVICE AND MAINTENANCE

C. HEATER JACKET PROPERLY INSTALLED ON CONVERTER TUBE

Temperature Sensor Leads

Thermocouple Lead

Converter Tube Inlet/Outlet Connections

Yellow Fiberglass Sleeving Exposed Outside of Jacket

Lace-On Heater Jacket

IGURE

556383-Y Rosemount Analytical July 2000

6-2. NO2

NO C

ONVERTER ASSEMBLY

Model 951A NO/NOx Analyzer

6-9

ERVICE AND MAINTENANCE

6.2.4 C

LEANING REACTION CHAMBER

CAUTION: LIGHT DAMAGE

Photomultiplier will develop temporary electronic noise if exposed to ambient light with high voltage on. Damage may be permanent if exposure occurs with high voltage off. A temporary noisy condition may be corrected by leaving instrument on, with high voltage on, for several hours. The required recovery time depends on intensity and duration of the exposure. Noise level on the most sensitive range usually drops to normal within 24 hours.

If sample gas is properly filtered, the reaction chamber should not require cleaning. In event of carryover or contamination, however, the chamber should be disassembled to permit cleaning the quartz window and the optical filter. The following procedure is recommended.

1. Turn off instrument power and shut off all gases.

2. Cover and shade the Reaction Chamber Photomultiplier Assembly, Figure 6-3, with a dark cloth or other light shielding material.

CAUTION: HAND PROTECTION

Always wear surgical rubber gloves when handling reaction chamber.

Reaction Chamber Assembly

Phototube Housing

Magnetic

Phototube

O-rings (1 or 2, depending on Phototube length. (Lubricate with silicone grease)

IGURE

Phototube Socket

ssembl

Proper orientation of photomultiplie r in s o c k e t may be determined by measuring the

resistance from the center pin to ground (should be approx im ate ly 11 megohm).

6-3. R

EACTION CHAMBER/PHOTOMULTIPLIER ASSEMBLY

6-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

3. At the front of the Reaction Chamber Photomultiplier Assembly, remove the three screws that secure the reaction chamber mounting bracket. See Figure 6-3. The middle screw is a 1/4-turn quick-release type; the two adjacent screws are the conventional continuous thread type.

4. With reaction chamber now free, detach its three tube fittings. See Figure 6-3.

5. Slide off and remove the reaction chamber from the housing. Take care not to let light enter.

6. Unscrew plastic end cap, Figure 6-4, thus freeing the quartz window and the red plastic optical filter.

7. Clean the reaction chamber by the appropriate one of the following two methods, “a” or “b”. Method “a” is applicable in most cases. Alternate method “b” is applicable when the instrument has shown high residual fluorescence, as indicated by high residual currents on a zero gas and high differentials between zero gas readings obtained with the ozone lamp on and off.

CAUTION: SOLVENT USAGE

For a solvent, use only distilled water, do not use alcohol or acetone.

Reaction Chamber Assembly

876351 O-ring

836486 O-ring

Quartz Window

IGURE

6-4. R

Phototube Housing

Optical Filter (Red Plastic)

Cap

EACTION CHAMBER ASSEMBLY AND PHOTOTUBE HOUSING

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-11

ERVICE AND MAINTENANCE

a. Standard Cleaning Procedure Using a stiff plastic bristle brush, such as a toothbrush, scrub the Teflon surface

and gas ports of the reaction chamber with clean distilled water and Alconox detergent (634929). Alconox detergent is included in the shipping kit provided with the Model 951A NO/NOx Analyzer and is also available from Sargent-Welch Scientific Company under its Catalog Number S-19650-A.

Using Alconox and clean, soft facial tissue (NOT industrial wipes), carefully clean

the quartz window, vigorously flush reaction chamber and quartz window with clean distilled water. Blow out all possible water from internal passages of reaction chamber. Dry reaction chamber and quartz window in a warm oven at 125oF to 150oF (52oC to 66oC) for 30 to 45 minutes or purge dry the parts

with dry cylinder air or nitrogen to eliminate all moisture. b. Alternate Cleaning Procedure - For High Residual Fluorescence Holding the reaction chamber by the tube fittings, and using appropriate caution.

immerse the white Teflon part of the chamber in 50% concentrated Reagent

Grade HCl. After five minutes, rinse thoroughly with deionized water, then air

dry as in method “a” above.

8. Place parts in position and press on end cap so that mating threads engage properly, without cross-threading. Turn mating parts in one continuous motion until the parts bottom. Do not over torque.

9. With reaction chamber now assembled, replace and reconnect it in the reverse order of that used for removal.

6.2.5 P

HOTOMULTIPLIER TUBE AND HOUSING

The photomultiplier tube operates at high DC voltages (nominal range 600 to 1200 volts) and generates small currents that are highly amplified by the signal conditioning circuitry. It is therefore important that ambient humidity and condensed water vapor be excluded from the interior of the photomultiplier housing. Ambient humidity can result in electrical leakage, evidenced as abnormally high dark current. Water vapor or condensed moisture in contact with the thermoelectrically-cooled photomultiplier may be evidenced by abnormally high noise level during instrument readout on zero air or upscale standard gas.

The Reaction Chamber Photomultiplier Assembly, Figure 6-3, incorporates several features for exclusion of humidity and moisture. The photomultiplier socket assembly is potted with a high impedance compound and is sealed from external influences with epoxy and rubber gasket material. The socket assembly and the reaction chamber are sealed, with o-rings, into opposite ends of the tubular photomultiplier housing. The socket end of the housing may be sealed with either one or two o-rings, depending on the length of the phototube.

6-12

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

In addition, a rolled-up piece of blotter-like desiccant paper is inserted between the shield external to the housing. The desiccant paper ensures hermetic isolation of the housing despite possible minor leakage around the o-rings, and eliminates the effects of any humidity possibly trapped during assembly of the socket and the reaction chamber to the housing. If the photomultiplier housing is exposed to ambient air for a period of tie, the desiccant paper will absorb water. Before reassembly, the paper must then be heated in an oven at about 300oF (149oC) for at least two hours.

Within the housing is a humidity indicator which turns pink in the presence of humidity.

6.2.6 T

EFLON LINER IN LAMP HOUSING OF OZONE GENERATOR

WARNING: MERCURY HAZARD

Handle lamp assembly with extreme caution. Lamp contains mercury vapor.

CAUTION: LAMP DAMAGE

Do not touch lamp. Fingerprints could cause a decrease in lamp output.

A Teflon liner was used inside the ozone lamp housing during early production runs of the Model 951A. A bare lamp housing is now used in lieu of the liner.

Inlet

Outlet

O-Ring

Ozone Lamp

ssembl

Connector Plug

For replacement of lamp only, order Ozone Lamp Kit 658156 (includes O-Ring). For replacement of complete Ozone Generator, order Kit 654793. Refer to instructions provided with kit.

IGURE

556383-Y Rosemount Analytical July 2000

6-5. O

ZONE GENERATOR

Model 951A NO/NOx Analyzer

6-13

ERVICE AND MAINTENANCE

6.3 SERVICING ELECTRONIC CIRCUITRY

Refer to the appropriate schematic and pictorial diagrams in the rear of this manual when servicing. The electronic system, Figure 7-2, utilizes plug in printed circuit boards with solid state components. After a malfunction is traced to a particular board, the recommended procedure is to return it to the factory for repair. Your Service Representative will arrange a Returned Goods Authorization.

6-14

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

ERVICE AND MAINTENANCE

1 WHT/GRN

8 WHT/ORN

9 WHT/ORN

12 GRY

CONV

ADJUST

9 WHT/ORN

1 WHT/GRN

11 WHT/RED

CONV LED

DS3

2 WHT/BLK

ON OFF

18 WHT/BRN

POWER

SW4

17 YEL

TB1

NEUT

HOT

REC -

REC +

6 5 4 3 2 1

14 ORN

4 WHT

24 WHT

12 GRY

25 WHT

(Top)

18 WHT/BRN

TB4

28 WHT

23 BLK

28 WHT

5 PUR

22 BLK

19 BLK

17 YEL

20 BLK

21 WHT 26 WHT

20 BLK 17 WHT

TB2

6 5

NEUT

4 3 2 1

NEUT

HOT

HOT NEUT HOT

120 VAC

19 BLK

10 BLU

16 BLK

15 RED

13 BRN

21 WHT

3 GRN/YEL

IGURE

16 BLK

15 RED

6-6. T

WIRE NO. COLOR FROM TO

649832 HARNESS

6 YEL

23 BLK

28 WHT

TB3

6 5 4 3 2 1

CONV

FAN

11 WHT/RED

14 ORN

13 BRN

6 YEL

10 BLU

5 PUR

7 WHT/BLU

2 WHT/BLK

3 GRN/YEL

4 WHT

8 WHT/ORN

THERM

CONV

7 WHT/BLU

ERMINAL CHASSIS ASSEMBLY WIRING DIAGRAM

1WHT/GRNDS3+J7-1 2WHT/BLKDS3 J7-A 3 GRN/YEL GND J7-C 4 WHT TB1-5 J7-D 5PUR F2 SideJ7-E 6 YEL TB3-6 J7-F 7 WHT/BLU TB3-1 J7-H 8 WHT/ORN TB3-2 J7-J

9 W HT/ORN R6 Slider J7-8 10 BLU TB4-3 J7-K 11 WHT/RED R6 CCW J7-9 12 GRY TB1-4 J7-L 13 BRN TB1-1 J7-M 14 ORN TB1-6 J7-P 15 RED TB4-1 J7-R 16 BLK TB4-2 J7-S 17 YEL F2 End SW4 18 WHT/BRN F1 Side SW4 19 BLK F1 End TB4-4 20 BLK F2 End TB2-2 21 BLK TB1-2 TB2-5 22 BLK TB2-2 TB2-6 23 BLK TB2-2 TB3-5 24 WHT TB1-2 TB1-3 25 WHT TB1-3 TB1-5 26 WHT TB2-3 TB2-5 27 WHT TB2-1 TB2-3 28 WHT TB2-1 TB3-4 29 Bare (Ti nned) R6 Slider R6 CW

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

6-15

ERVICE AND MAINTENANCE

OTES

6-16

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

EPLACEMENT PARTS

The following parts are recommended for routine maintenance and troubleshooting of your instrument. If the troubleshooting procedures do not resolve the problem, contact your local service office.

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, as 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 REPLACEMENT PARTS

621095 ±15V Power Supply 649815 Amplifier Board 652842 Ballast Transformer, Ozone Gener ator 623719 Capillary, Sam ple 623743 Capillary, Pump 634398 Capillary, Bleed 630960 Coaxial Cable, Amplifier 632783 Converter Assembl 861273 Fan 809374 Fuse 3/4 Amp 777010 Fuse 5 Amp (Package of 15) 658992 High Voltage Power Supply Board 630920 Interconnect Board 630931 Meter 654793 Ozone Generator See Section 7.2.3 658156 Ozone Generator Lamp Kit (Lamp Only) 657842 Power Supply Board 632748 Pump (Option) 635664 Pump Repair Kit 636343 Reaction Chamber 902315 Signal Converter 4-20mA (Option) 641620 Temperature Control Board 624593 Valve Control Board

See Section 7.2.2

See section noted for components of assembly.

556383-Y Rosemount Analytical July 2000

Model 951A NO/NOx Analyzer

7-1

EPLACEMENT PARTS

Pneumatics (see Figure 7-3)

Pump (Option)

Ozone Generator

Interlock Switch

Fan

Power Switch

Meter

Power Switch Shield

Ballast Transformer

Converter Assembly (see Figure 7-4)

IGURE

7-2

7-1A. M

ODEL

951A

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

Coaxial Amplifier Cable

Electronics (see Figure 7-2)

Terminal Chassis Assembly

EPLACEMENT PARTS

Reaction Chamber

Thermocouple Connector

IGURE

556383-Y Rosemount Analytical July 2000

7-1B. M

ODEL

951A

Model 951A NO/NOx Analyzer

7-3

EPLACEMENT PARTS

IGURE

7-4

7-1C. M

ODEL

951A

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

High Voltage Power Supply Board

Amplifer Board

±15V Power Supply

EPLACEMENT PARTS

Interconnect Board

IGURE

556383-Y Rosemount Analytical July 2000

7-2. E

LECTRONICS

Temperature Control Board

Valve Control Board

Model 951A NO/NOx Analyzer

7-5

EPLACEMENT PARTS

7.2.1 P

638614 Pressure Gauge, Ozone 644055 Pressure Gauge, Sample 839906 Flowmeter, Bypass 815187 Backpressure Regulator, Sample 634993 Needle Valve, Bypass 888692 Pressure Regulator, Ozone 652146 Tee Fitting Assembly 107542 Metering Valve, Flow Balance

NEUMATICS

Metering Valve

Sample Pressure Gauge

Bypass Flowmeter

IGURE

7-3. F

Needle Valve

Tee Fitting Assembly

Ozone Pressure Gauge

RONT PANEL PNEUMATIC COMPONENTS

Sample Backpressure Regulator

Ozone Pressure Regulator

7-6

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

EPLACEMENT PARTS

7.2.2 C

ONVERTER ASSEMBLY

632782 Sensor 632784 Connector, Tube 632795 Tube, Packed - Aged 617124 Heater Jacket 623848 Thermocouple, Type J 876776 Solenoid Valve - 3-Way 879948 Nut, Teflon 3/32

Sensor

3-Way Solenoid Valve

Teflon Nut 3/32

Connector Tubes

Heater Jacket

Type J Thermocouple

IGURE

556383-Y Rosemount Analytical July 2000

7-4. C

ONVERTER COMPONENTS

Model 951A NO/NOx Analyzer

7-7

EPLACEMENT PARTS

Inlet

Outlet

O-Ring

Ozone Lamp Assembly

Connector Plug

For replacement of lamp only, order Ozone Lamp Kit 658156 (includes O-Ring). For replacement of complete Ozone Generator, order Kit 654793. Refer to instructions

IGURE

7-5. O

rovided with kit.

ZONE GENERATOR COMPONENTS

7-8

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

EPLACEMENT PARTS

7.2.3 L

OW TEMPCO OPTION

652831 Power Supply Assembly 654831 Reaction Chamber 861040 Sensor, Cooler Temperature 884791 Thermistor 654943 Thermoelectric Cooler Assembly 652836 Transformer, Thermo el ectri c Cooler

BALLAS

TOROID TRANSFORME

INDUCTOR

OZONE GENERATOR

THERMO COOLER POWER

THERMO COOLER INDICATOR

FAN

CHASSIS TERMINA

BAFFL

IGURE

556383-Y Rosemount Analytical July 2000

7-6. T

EMPCO RETROFIT COMPONENT LOCATION

THERMO COOLER ASSY

ELECTRONICS

CONVERTER ASSY

Model 951A NO/NOx Analyzer

7-9

EPLACEMENT PARTS

OTES

7-10

July 2000 Rosemount Analytical 556383-YModel 951A NO/NOx Analyzer

Rosemount 951A NO/NOx Analyzer-Rev Y Manuals & Guides

Specifications and Main Features

Frequently Asked Questions

User Manual