Instruction Manual
556383-Z
March 2002
http://www.processanalytic.com
Model 951A
NO/NOx Analyzer
Emerson Process Management
Rosemount Analytical Inc.
Process Analytic Division
1201 N. Main St.
Orrville, OH 44667-0901
T (330) 682-9010
F (330) 684-4434
e-mail: [email protected]
http://www.processanalytic.com
ESSENTIAL INSTRUCTIONS
READ THIS PAGE BEFORE PROCEEDING!
Rosemount Analytical designs, manufactures and tests its products to meet many national and
international standards. Because these instruments are sophisticated technical products, you
MUST properly install, use, and maintain them to ensure they continue to operate within their
normal specifications. The following instructions MUST be adhered to and integrated into your
safety program when installing, using, and maintaining Rosemount Analytical products. Failure to
follow the proper instructions may cause any one of the following situations to occur: Loss of life;
personal injury; property damage; damage to this instrument; and warranty invalidation.
• Read all instructions prior to installing, operating, and servicing the product.
• If you do not understand any of the instructions, contact your Rosemount Analytical repre-
sentative for clarification.
• Follow all warnings, cautions, and instructions marked on and supplied with the product.
• Inform and educate your personnel in the proper installation, operation, and mainte-
nance of the product.
• Install your equipment as specified in the Installation Instructions of the appropriate In-
struction Manual and per applicable local and national codes. Connect all products to the
proper electrical and pressure sources.
• To ensure proper performance, use qualified personnel to install, operate, update, program,
and maintain the product.
• When replacement parts are required, ensure that qualified people use replacement parts
specified by Rosemount. Unauthorized parts and procedures can affect the product’s per-
formance, place the safe operation of your process at risk, and VOID YOUR WARRANTY.
Look-alike substitutions may result in fire, electrical hazards, or improper operation.
• Ensure that all equipment doors are closed and protective covers are in place, except
when maintenance is being performed by qualified persons, to prevent electrical shock
and personal injury.
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.
Alconox ® is a registered trademark of Alconox, Inc.
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Contents i
Model 951A
TABLE OF CONTENTS
PREFACE...........................................................................................................................................P-1
Definitions ...........................................................................................................................................P-1
Intended Use Statement.....................................................................................................................P-2
Safety Summary .................................................................................................................................P-2
General Precautions For Handling And Storing High Pressure Gas Cylinders .................................P-4
Documentation....................................................................................................................................P-5
Compliances .......................................................................................................................................P-5
1-0 DESCRIPTION AND SPECIFICATIONS..............................................................................1-1
1-1 Overview................................................................................................................................1-1
1-2 Options ..................................................................................................................................1-2
a. Range I.D. .......................................................................................................................1-2
b. Remote Range Change ..................................................................................................1-2
c. Range I.D. and Remote Range Change.........................................................................1-2
d. Sample Pump..................................................................................................................1-2
1-3 Specifications ........................................................................................................................1-3
2-0 INSTALLATION ....................................................................................................................2-1
2-1 Facility Preparation................................................................................................................2-1
a. Outline and Mounting Dimensions ..................................................................................2-1
b. Location...........................................................................................................................2-1
c. Power Requirements ......................................................................................................2-1
2-2 Unpacking..............................................................................................................................2-1
2-3 Gas Requirements.................................................................................................................2-1
a. Air Or Oxygen .................................................................................................................2-1
b. Span Gas ........................................................................................................................2-2
2-4 Sample Requirements ...........................................................................................................2-2
2-5 Gas Connections ...................................................................................................................2-2
2-6 Electrical Connections ...........................................................................................................2-6
a. Recorder Output..............................................................................................................2-6
b. Thermocouple Connections for Measuring Temperature of NO
2
to NO Converter ........2-6
c. Remote Range Change ..................................................................................................2-6
d. Connections of the Range I. D. Kit..................................................................................2-6
e. Power Connections.........................................................................................................2-6
3-0 STARTUP AND OPERATION ..............................................................................................3-1
3-1 Startup Procedure .................................................................................................................3-1
3-2 Calibration..............................................................................................................................3-3
3-3 Measuring Efficiency Of No
2
To No Converter And Adjusting Temperature Setpoint ..........3-4
a. Test Setup for Measurement of Conversion Efficiency...................................................3-4
b. Test Procedure................................................................................................................3-4
c. Subnormal Conversion Efficiency...................................................................................3-8
d. Replacement of Converter ..............................................................................................3-8
e. Capillaries .......................................................................................................................3-8
f. TEA Scrubber..................................................................................................................3-9
3-4 Routine Operation .................................................................................................................3-9
3-5 Recommended Calibration Frequency..................................................................................3-9
Instruction Manual
556383-Z
March 2002
ii Contents Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
4-0 THEORY................................................................................................................................4-1
4-1 Principles Of Operation .........................................................................................................4-1
a. Nitric Oxide Determination By Chemiluminescense Method ..........................................4-1
b. NO
X
Determination..........................................................................................................4-1
c. Ozone Generation...........................................................................................................4-1
4-2 Analyzer Flow System ...........................................................................................................4-1
a. Flow Of Sample Or Standard Gas To Reaction Chamber..............................................4-1
b. Flow of Air or Oxygen .....................................................................................................4-3
c. Flow System Operating Modes.......................................................................................4-3
d. Converter Bleed Flow .....................................................................................................4-4
4-3 Electronic Circuitry.................................................................................................................4-4
a. Amplifier Board and Associated Circuitry .......................................................................4-5
b. Valve Control Board, Front Panel Mode Switch and Associated Circuitry .....................4-6
c. ±15 Volt Power Supply ....................................................................................................4-6
d. High Voltage Power Supply ............................................................................................4-7
e. Converter Temperature Control Board and Associated Elements .................................4-7
f. Fan Control Circuit ..........................................................................................................4-8
g. Remote Operation Option ...............................................................................................4-8
h. Range I.D. Option ...........................................................................................................4-8
5-0 ROUTINE SERVICING..........................................................................................................5-1
5-1 System Checks And Adjustments .........................................................................................5-1
a. Meter Mechanical Zero ...................................................................................................5-1
b. Amplifier Zero Adjustments.............................................................................................5-1
c. Inter-Range Attenuation Correlation adjustments...........................................................5-1
d. Meter Fullscale Span Adjustment ...................................................................................5-2
e. Overall Sensitivity............................................................................................................5-3
f. Ozone Output..................................................................................................................5-3
g. Background Current........................................................................................................5-3
h. NO
2
to NO Converter Temperature Adjustment .............................................................5-4
i. Flow Balance...................................................................................................................5-4
5-2 Servicing Flow System ..........................................................................................................5-5
a. Sample Capillary .............................................................................................................5-5
b. Ozone Restrictor and Capillary .......................................................................................5-6
5-3 NO
2
To NO Converter............................................................................................................5-7
a. Replacing ........................................................................................................................5-7
5-4 Photomultiplier/Reaction Chamber........................................................................................5-8
a. Cleaning Reaction Chamber...........................................................................................5-8
b. Photomultiplier Tube and Housing..................................................................................5-10
5-5 Servicing Electronic Circuitry.................................................................................................5-11
6-0 REPLACEMENT PARTS ......................................................................................................6-1
6-1 Circuit Board Replacement Policy .........................................................................................6-1
6-2 Matrix .....................................................................................................................................6-1
6-3 Replacement Parts ................................................................................................................6-2
a. Pneumatics .....................................................................................................................6-7
b. Converter Assembly........................................................................................................6-8
c. Low Tempco Option ........................................................................................................6-10
7-0 RETURN OF MATERIAL ....................................................................................................7-1
7-1 Return Of Material .................................................................................................................7-1
7-2 Customer Service ..................................................................................................................7-1
7-3 Training..................................................................................................................................7-1
Instruction Manual
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March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Contents iii
Model 951A
LIST OF ILLUSTRATIONS
Figure 1-1. Model 951A NO/NO
X
Analyzer .............................................................................. 1-1
Figure 2-1. Model 951A Outline and Mounting Dimensions .................................................... 2-3
Figure 2-2. Front Panel Indicators and Controls ...................................................................... 2-4
Figure 2-3. Controls and Adjustments Located Behind Swing Out Front Panel...................... 2-4
Figure 2-4. Rear Panel............................................................................................................. 2-4
Figure 2-5. Remote Range Kit Installed................................................................................... 2-7
Figure 2-6. Typical Interconnection of Remote Range Kit ....................................................... 2-7
Figure 3-1. Amplifier Board Adjustments ................................................................................. 3-3
Figure 3-2. Measuring Efficiency of NO
2
to NO Converter ...................................................... 3-7
Figure 3-3. Conversion Efficiency as a Function of Converter Temperature........................... 3-8
Figure 4-1. Schematic Flow Diagram of Model 951A .............................................................. 4-2
Figure 4-2. Functional Schematic Diagram of Electronic Signal Circuitry ............................... 4-5
Figure 5-1. Amplifier Board ......................................................................................................5-2
Figure 5-2. NO
2
to NO Converter Assembly ............................................................................ 5-7
Figure 5-3. Reaction Chamber/Photomultiplier Assembly ....................................................... 5-9
Figure 5-4. Reaction Chamber Assembly and Phototube Housing ......................................... 5-9
Figure 5-5. Terminal Chassis Assembly Wiring Diagram ...................................................... 5-12
Figure 6-1. Model 951A – Exploded View................................................................................ 6-3
Figure 6-2. Model 951A – Exploded View (continued)............................................................. 6-4
Figure 6-3. Model 951A – Exploded View (continued)............................................................. 6-5
Figure 6-4. Electronics ............................................................................................................. 6-6
Figure 6-5. Front Panel Pneumatic Components..................................................................... 6-7
Figure 6-6. Converter Components.......................................................................................... 6-8
Figure 6-7. Ozone Generator Components.............................................................................. 6-9
Figure 6-8. Tempco Retrofit Component Location................................................................. 6-10
LIST OF TABLES
Table 2-1. Model 951A Controls and Adjustments ................................................................. 2-5
Table 3-1. Proper Gas Supply Pressures for Various Levels of Sample NO
X
........................ 3-2
Instruction Manual
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March 2002
iv Contents Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
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
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-1
Model 951A
PREFACE
The purpose of this manual is to provide information concerning the components, functions, in-
stallation and maintenance of the Model 951A .
Some sections may describe equipment not used in your configuration. The user should become
thoroughly familiar with the operation of this analyzer before operating it. Read this instruction
manual completely.
DEFINITIONS
The following definitions apply to DANGERS, WARNINGS, CAUTIONS and NOTES found throughout
this publication.
DANGER .
Highlights the presence of a hazard which will cause severe personal injury, death, or substantial
property damage if the warning is ignored.
WARNING .
Highlights an operation or maintenance procedure, practice, condition, statement, etc. If not
strictly observed, could result in injury, death, or long-term health hazards of personnel.
CAUTION.
Highlights an operation or maintenance procedure, practice, condition, statement, etc. If not
strictly observed, could result in damage to or destruction of equipment, or loss of effectiveness.
NOTE
Highlights an essential operating procedure,
condition or statement.
Instruction Manual
556383-Z
March 2002
P-2 Preface Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
INTENDED USE STATEMENT
The Model 951A NO/NOx Analyzer is intended for use as an industrial process measurement device
only. It is not intended for use in medical, diagnostic, or life support applications, and no inde-
pendent agency certifications or approvals are to be implied as covering such applications.
SAFETY SUMMARY
If this equipment is used in a manner not specified in these instructions, protective systems may be
impaired.
AUTHORIZED PERSONNEL
To avoid explosion, loss of life, personal injury and damage to this equipment and on-site property,
do not operate or service this instrument before reading and understanding this instruction manual
and receiving appropriate training. Save these instructions.
DANGER.
ELECTRICAL SHOCK HAZARD
Do not operate without doors and covers secure.. Installation requires access to live parts which
can cause death or serious injury.
For safety and proper performance this instrument must be connected to a properly grounded
three-wire source of power.
DANGER.
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.
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-3
Model 951A
DANGER.
OZONE HAZARD
This instrument generates ozone while operating. Ozone is toxic by inhalation and is a strong irri-
tant 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 ex-
haust of an internal combustion engine, it may contain unburned hydrocarbons and carbon mon-
oxide 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 separate lines 1/4 inch
(6.3mm) or larger. Use only Teflon or stainless steel tubing.
WARNING.
PARTS INTEGRITY
Tampering with or unauthorized substitution of components may adversely affect the safety of this
instrument. Use only factory approved components for repair.
CAUTION
AIR FLOW
Do not operate instrument without air flow to the ozonator; plugging of the filter will result.
CAUTION.
PRESSURIZED GAS
This unit requires periodic calibration with a known standard gas. It also may utilizes a pressur-
ized carrier gas, such as helium, hydrogen, or nitrogen. See General Precautions for Handling and
Storing High Pressure Gas Cylinders, page P-4.
Instruction Manual
556383-Z
March 2002
P-4 Preface Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
GENERAL PRECAUTIONS FOR HANDLING AND STORING HIGH
PRESSURE GAS CYLINDERS
Edited from selected paragraphs of the Compressed Gas Association's "Handbook of Compressed
Gases" published in 1981
Compressed Gas Association
1235 Jefferson Davis Highway
Arlington, Virginia 22202
Used by Permission
1. Never drop cylinders or permit them to strike each other violently.
2. Cylinders may be stored in the open, but in such cases, should be protected against extremes of
weather and, to prevent rusting, from the dampness of the ground. Cylinders should be stored in the
shade when located in areas where extreme temperatures are prevalent.
3. The valve protection cap should be left on each cylinder until it has been secured against a wall or
bench, or placed in a cylinder stand, and is ready to be used.
4. Avoid dragging, rolling, or sliding cylinders, even for a short distance; they should be moved by using a
suitable hand-truck.
5. Never tamper with safety devices in valves or cylinders.
6. Do not store full and empty cylinders together. Serious suckback can occur when an empty cylinder is
attached to a pressurized system.
7. No part of cylinder should be subjected to a temperature higher than 125
°
F (52
°
C). A flame should
never be permitted to come in contact with any part of a compressed gas cylinder.
8. Do not place cylinders where they may become part of an electric circuit. When electric arc welding,
precautions must be taken to prevent striking an arc against the cylinder.
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Preface P-5
Model 951A
DOCUMENTATION
The following Model 951A NO/NOx Analyzer instruction materials are available. Contact Customer Serv-
ice Center or the local representative to order.
556383 Instruction Manual (this document)
COMPLIANCES
This product may carry approvals from several certifying agencies, for use in non-hazardous, indoor loca-
tions.
97-C218
Instruction Manual
556383-Z
March 2002
P-6 Preface Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-1
Model 951A
SECTION 1
DESCRIPTION AND SPECIFICATIONS
1-1 OVERVIEW
The Model 951A NO/NO
X
Analyzer continu-
ously analyzes a flowing gas sample per-
forming one of two switch selectable
determinations:
1. Nitric oxide (NO); or
2. Combined nitric oxide (NO) and nitrogen
dioxide (NO
2
) designated NO
X
. By defini-
tion [NO
X
] = [NO] + [NO
2
].
Typical applications include analyzing ve-
hicular exhaust emissions from internal com-
bustion engines and monitoring the effluent
from stationary (stack) sources
The analyzer utilizes the chemiluminescent
method of detection In the nitric oxide deter-
mination, sample NO is quantitatively con-
verted into NO
2
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 NO
2
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 photomul-
tiplier detector generating a low-level DC cur-
rent. The current is amplified to drive a front
panel meter and an accessory potentiometric
recorder if desired.
To minimize noise and reduce dark current,
the photomultiplier tube is mounted in a ther-
moelectrically-cooled housing with tempera-
ture held constant at about 59
o
F (15
o
C).
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 ther-
mistor 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 150
o
F (65
o
C). This fuse protects
the thermoelectric cooler against the over-
heating that otherwise could occur as a result
of excessively high ambient temperature or
failure of a fan.
Figure 1-1. Model 951A NO/NO
X
Analyzer
CONVERTER
ADJUST
ZERO
SPAN
PPM RANGE
10 AUTO
25 10000
100 2500
250 1000
MODE
NO NOx
ON
OFF
Rosemount Analytical
Model 951A NO/NOx Analyzer
Instruction Manual
556383-Z
March 2002
1-2 Description and Specifications Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
CAUTION
EXCESSIVE HEAT
Do not operate this analyzer without the air
duct covering the cooling fins of the ther-
moelectric 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 NO
X
determina-
tion 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 NO
2
component is dissociated to form NO. In-
strument 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 NO
2
.
To minimize system response time an internal
sample-bypass feature provides high-velocity
sample flow through the analyzer.
The electronic circuitry is modularized, utiliz-
ing plug-in printed 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 ad-
dition to the standard features of the basic in-
strument. Brief descriptions of the principal
options are given in the following section.
1-2 OPTIONS
a. Range I.D.
This option provides contact closure sig-
nals that enable a computer or other ex-
ternal device to identify the setting of the
front panel PPM RANGE Switch. The
Model 951A is designed to continuously
measure the concentration 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 sam-
ple 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.
b. Remote Range Change
For applications where remote operation
of the analyzer is desired, as in an emis-
sion 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 NO
X
mode, and (b) ppm range.
The unit consists of an electrical plug
connector with plug-in logic card and har-
ness for connection to a rear panel termi-
nal strip on the analyzer.
c. Range I.D. and Remote Range Change
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 termi-
nal strip on the rear of the analyzer for
connections of the user cable.
d. Sample Pump
The basic Model 951A is designed to ac-
cept 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.
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Description and Specifications 1-3
Model 951A
1-3 SPECIFICATIONS
Catalog Number ............................ 193702 Model 951A NO/NO
X
Analyzer
Ranges .......................................... Selectable fullscale range of 10, 25, 100, 250, 1000, 2500 and
10,000 parts per million
Sensitivity ...................................... 0.1 ppm on 10 ppm range
Linearity ......................................... ±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.
Response Time (Electronic Plus Flow)
Standard Sample Capillary.... Approximately one second on all ranges except 10 ppm.
Approximately three seconds on 10 ppm range.
Auxiliary Sample Capillary..... Five seconds on all ranges.
For such applications as monitoring stack sources, where compara-
tively slow response is desired, an internal switch provides an op-
tional electronic response time of approximately 10 seconds to 90%
of fullscale on all ranges.
Precision........................................ ±5% of fullscale
Stability
Zero ....................................... 1% of fullscale in 24 hours
Span ...................................... 1% of fullscale in 24 hours
Detector Operating Temperature .. Atmospheric
Recorder Output............................ Selectable output of 10 millivolts, 100 millivolts, 1 volt or 5 volts
Ambient Temperature.................... 40°F to 100°F (4.4°C to 37.7°C)
Electrical Power Requirements ..... 107 to 127 VAC, 50/60 Hz, 1000 watts
Dimensions.................................... 9.0 x 17.8 x 22.0 inches (228.6 x 450.9 x 558.8mm) HxWxD
Weight ........................................... 76 lbs. (34.5 kg)
Instruction Manual
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March 2002
1-4 Description and Specifications Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Installation 2-1
Model 951A
SECTION 2
INSTALLATION
2-1 FACILITY PREPARATION
Sections 2-1a through 2-1c provide informa-
tion that may be required prior to installation
of the analyzer.
a. Outline and Mounting Dimensions
Significant dimensions are shown in Fig-
ure 2-1.
b. Location
Install analyzer in a clean area, not sub-
ject 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 inter-
nal temperature of the analyzer to the cor-
rect operating temperature for ambient
temperatures in the range 40
o
F to 100
o
F
(4.4
o
C to 37.7
o
C). Temperatures outside
these limits necessitate use of special
temperature controlling equipment or en-
vironmental protection.
Preferably, the cylinders of air (or oxygen)
and span gas should be located in an
area of relatively constant ambient tem-
perature.
c. Power 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 in-
strument and marked with red paint for identi-
fication. 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.
2-3 GAS REQUIREMENTS
CAUTION
HIGH PRESSURE GAS CYLINDERS
This instrument requires use of oxygen
and a known standard gas in high pres-
sure cylinders. Refer to Handling and
Storing High Pressure Gas Cylinders lo-
cated on page P-4.
a. Air or Oxygen
This is used as both (a) oxygen source for
generation of the ozone required for the
chemiluminescent reaction, and (b) stan-
dard gas for zero calibration. Gas for both
purposes may be supplied from a single
cylinder and routed through a tee. Alter-
natively, 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
ppm or less. Breathing grade oxygen or
air is recommended. Clean, dried ambient
air containing less than 0.1 ppm nitric ox-
ide may be used, provided that its dew-
point is below -10
o
F (-23
o
C). If air is
insufficiently dried, or contains excessive
nitric oxide, instrument response will not
be linear to 2500 ppm.
Instruction Manual
556383-Z
March 2002
2-2 Installation Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
b. Span Gas
This is a standard gas of accurately
known composition, used to set an up-
scale calibration point.
Alternative span gases are:
1. The usual span gas is NO in a back-
ground of nitrogen.
2. For span check or adjustment in the
NO
X
mode, the span gas may be NO
2
in a background of air or nitrogen.
3. For convenient calibration in either
the NO or NO
X
mode, the span gas
may be a cylinder gas mixture con-
sisting of known concentrations of
both NO and NO
2
in a background of
nitrogen.
NOTE
For maximum calibration accuracy, the
concentration of NO and/or NO
2
in the
span gas should be as near as possi-
ble 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 regula-
tor may be utilized immediately up-
stream from the SAMPLE inlet.
Preferably, each gas used should be sup-
plied 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 cylin-
ders in an area of relatively constant am-
bient temperature.
2-4 SAMPLE REQUIREMENTS
The Sample must be relatively clean and dry
before entering the analyzer. In general, be-
fore admission to the analyzer, the sample
should be filtered to 2 microns and should
have a dewpoint below 90
o
F (32
o
C). The fac-
tory can provide technical assistance if de-
sired .
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 SAM-
PLE 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 SAM-
PLE 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.
2-5 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 oxy-
gen) cylinder and sample source to corre-
sponding rear panel inlet ports. For
sample line, stainless steel tubing is rec-
ommended.
4. Adjust regulator on air (or oxygen) cylin-
der for output pressure of 35 to 40 psig
(251 to 276 kPa).
5. 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.
Instruction Manual
556383-Z
March 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Installation 2-3
Model 951A
Figure 2-1. Model 951A Outline and Mounting Dimensions
19.0
[482]
8.7
[222]
9.0
[228]
1.0
[25.4]
20.2
[513]
1.25
[32]
6.0
[152]
1.25
[32]
4.5
[
114
]
2.0
[51]
7.0
[178]
8.7
[221]
2.8
[70]
4.6
[118]
6.6
[
168
]
18.3
[465]
18.3
[465]
18.3
[465]
18.3
[465]
18.3
[465]
8.5
[216]
∅
.25
[63]
6 PLC'S
RECOMMENDED PANEL CUTOUT
3. ALLOW 16 INCHES IN FRONT OF INSTRU-
MENT FOR DOOR SWING.
2. ALLOW 12 INCHES MINIMUM CLEARANCE
ABOVE INSTRUMENT FOR MAINTENANCE..
1. RECOMMENDED MOUNTING HARDWARD:
10-32 MACHINE SCREWS (SUPPLIED BY
CUSTOMER).
DIMENSIONS
Inch
mm
Instruction Manual
556383-Z
March 2002
2-4 Installation Rosemount Analytical Inc. A Division of Emerson Process Management
Model 951A
Thermocouple
Connector TB9
Sample Inlet
A
ir Inlet
Exhaust
Fuse F1 Fuse F2
Recorder Connection TB4-2
Range I.D. Connec-
tor J10 (option)
Cable Gland For Re-
corder Cable
AC Power Cable
Recorder Connection TB4-1
Figure 2-2. Front Panel Indicators and Controls
Figure 2-3. Controls and Adjustments Located Behind Swing Out Front Panel
Figure 2-4. Rear Panel
FLOW
BALANCE
OZONE
OZONE
OFF
B
Y
P
A
S
S
ON
OFF
SPAN
ZERO
CONVERTER
ADJUST
PPM RANGEMODE
250
100
25
10
1000
2500
10000
AUTO
NO NOx
Rosemount Anal
y
tical
Model 951A NO/NOx Anal
y
zer
PPM Range Switch
Bypass Flowmeter
Ozone Pressure
Gauge
Meter
AC Power
On/off Switch
Mode
Switch
Converter Adjust
Converter Indicator
Span Adjust
Zero Adjust
Sample Pressure Gauge
Rosemount Anal
y
tical
Model 951A NO/NOx Anal
y
zer
FLOW
BALANCE
OZONE
OZONE
OFF
B
Y
P
A
S
S
10
100
MV
REC
5
1
V
OUTPUT
FAST SLOW
RESPONSE
R22
R34
CALIB
R16
R33
CALIB
R31
CALIB
R32
CALIB
R6
INPUT
Ozone Off Push-
button Switch
Photomultiplier High
Voltage Interlock
Switch
Recorder Output
Select Switch
Response Time Selector Switch
Bypass Needle Valve
Ozone Pressure
Regulator
Flow Balance Needle Valve
Sample Backpressure Regulator
Bypass Flowmeter
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