Model 951C NOx Analyzer
Instruction Manual
748214-X
December 2013
Applies to analyzers with SN# F-09000034 or higher.
TABLE OF CONTENTS
Section 1: Description and specifications
Typical applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Section 2: Installation
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Voltage requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Operating on 230 VAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Connecting cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Connecting the power cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Connecting the potentiometric recorder cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Connecting the current recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Adjusting the current output to produce a zero of 0 mA . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Gas requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Air (U.S.P. Breathing Grade) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Span Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Sample requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8
Connecting gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Leak testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
Section 3: Operation
Front panel indicators and controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Range selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Blinking backlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
Sample pressure gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Ozone pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
Zero and span potentiometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Ozone interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Starting the analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
Setting up remote range switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9
Calibrating the analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
Zero calibrating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
Upscale calibrating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12
Optimizing the converter temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13
Measuring converter efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-16
Recommended calibration frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17
i
Section 4: Theory
Nitric oxide concentration is determination by chemiluminescence method . . . . . . . . . . . . . . . . . . . 4-1
Analyzer flow system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Flow of sample, standard gas or zero gas to reaction chamber . . . . . . . . . . . . . . . . . . . 4-4
Ozone generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Signal conditioning and display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Circuit functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
Analyzer thermal system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Section 5: Routine servicing
System checks and adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Adjusting the display fullscale span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Factors affecting the overall sensitivity of the analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Monitoring ozone output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Finding the cause of excessive background current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Servicing the flow system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Cleaning the sample capillary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Confirming a faulty ozone restrictor fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
Servicing the photomultiplier tube and the reaction chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
Removing or replacing the photomultiplier assembly . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
Cleaning the reaction chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11
Reconstructing the photomultiplier assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15
Photomultiplier tube and housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
Replacing the photomultiplier tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
Ozone generator assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Removing the ultraviolet lamp and lamp housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-17
Replacing the ultraviolet lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Removing the power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18
Converter assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-19
Removing the glass converter tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20
Servicing the electronic circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20
Section 6: Replacement parts
Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
Circuit board replacement policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Replacement parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Common parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Photomultiplier assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Converter assembly 654070 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
Temperature control assembly 654068 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
ii
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
representative 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
maintenance of the product.
• Install your equipment as specified in the Installation Instructions of the appropriate
Instruction 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
performance, 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.
This page is intentionally left blank.
PREFACE
Highlights the presence of a hazard which will cause severe personal injury, death, or substantial
property damage if the warning is ignored.
DANGER
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.
WARNING
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.
CAUTION
Highlights an essential operating procedure, condition or statement.
NOTE
The purpose of this manual is to provide information concerning the components,
functions, installation and maintenance of the 951C NOx analyzer.
Some sections may describe equipment not used in your configuration. The user
should become thoroughly familiar with the operation of this module before operating
it. Read this instruction manual completely.
DEFINITIONS
The following definitions apply to dangers, warnings, cautions and notes found
throughout this publication.
vii
SAFETY SUMMARY
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.
This instrument was shipped from factory set up to operate on 115 volt 50/60 Hz. For operation on
230 volt 50/60 Hz, refer to Section 2-3.
For safety and proper performance this instrument must be connected to a properly grounded threewire source of power.
DANGER
INTERNAL ULTRAVIOLET LIGHT HAZARD
Ultraviolet light from the ozone generator can cause permanent eye damage. Do not look directly at
the ultraviolet source in ozone generator. Use of ultraviolet filtering glasses is recommended.
WARNING
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, all personnel authorized to install, operate and service the this
equipment should be thoroughly familiar with and strictly follow the instructions in this
manual. SAVE THESE IN-STRUCTIONS.
viii
TOXIC CHEMICAL HAZARD
This instrument generates ozone which is toxic by inhalation and is a strong irritant to throat and
lungs. Ozone is also a strong oxidizing agent. Its presence is detected by a characteristic pungent
odor.
The instrument exhaust contains both ozone and nitrogen dioxide, both toxic by inhalation, and may
contain other constituents of the sample gas which may be toxic. Such gases include various
oxides of nitrogen, unburned hydrocarbons, carbon monoxide and other products of combustion
reactions. Carbon monoxide is highly toxic and can cause headache, nausea, loss of
consciousness, and death.
Avoid inhalation of the ozone produced within the analyzer and avoid inhalation of the sample and
exhaust products transported within the analyzer. Avoid inhalation of the combined exhaust
products at the exhaust fitting.
WARNING
PARTS INTEGRITY
Tampering or unauthorized substitution of components may adversely affect safety of this product.
Use only factory documented components for repair.
WARNING
HIGH PRESSURE GAS CYLINDERS
This instrument requires periodic calibration with a known standard gas. See Sections 2-5 and 3-3.
See also General Precautions for Handling and Storing High Pressure Gas Cylinders, page P-5.
WARNING
ix
TOXIC AND OXIDIZING GAS HAZARD
The ozone generator lamp contains mercury. Lamp breakage could result in mercury exposure.
Mercury is highly toxic if absorbed through skin or ingested, or if vapors are inhaled.
HANDLE LAMP ASSEMBLY WITH EXTREME CARE
If lamp is broken, avoid skin contact and inhalation in the area of the lamp or the mercury spill.
Immediately clean up and dispose of the mercury spill and lamp residue as follows:
• Wearing rubber gloves and goggles, collect all droplets of mercury by means of a suction pump and
aspirator bottle with long capillary tube. Alternatively, a commercially available mercury spill cleanup kit, such as J. T. Baker product No. 4439-01, is recommended.
• Carefully sweep any remaining mercury and lamp debris into a dust pan. Carefully transfer all
mercury, lamp residue and debris into a plastic bottle which can be tightly capped. Label and return
to hazardous material reclamation center.
• Do not place in trash, incinerate or flush down sewer.
• Cover any fine droplets of mercury in non-accessible crevices with calcium polysulfide and sulfur
dust.
WARNING
TOPPLING HAZARD
This instrument's internal pullout chassis is equipped with a safety stop latch located on the left
side of the chassis.
When extracting the chassis, verify that the safety latch is in its proper (counter-clockwise)
orientation.
If access to the rear of the chassis is required, the safety stop may be overridden by lifting the
latch; however, further extraction must be done very carefully to insure the chassis does not fall
out of its enclosure.
If the instrument is located on top of a table or bench near the edge, and the chassis is extracted, it
must be supported to prevent toppling.
WARNING
x
GENERAL PRECAUTIONS FOR HANDLING AND
STORING HIGH PRESSURE GAS CYLINDERS
• Never drop cylinders or permit them to strike each other violently.
• 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.
• 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.
• Avoid dragging, rolling, or sliding cylinders, even for a short distance; they
should be moved by using a suit-able hand-truck.
• Never tamper with safety devices in valves or cylinders.
• Do not store full and empty cylinders together. Serious suck-back can occur
when an empty cylinder is attached to a pressurized system.
• 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.
1
• 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.
1. Compressed Gas Association, Handbook of Compressed Gases, Second Edition, Van Nostrand
Reinhold Company, 135 West 50th Street, New York, NY 10020, © 1981.
xi
CONDENSED STARTUP AND CALIBRATION
PROCEDURE
The following summarized instructions on startup and calibration are intended for
operators already familiar with the analyzer.
For initial startup, refer to detailed instructions provided in “Operation” on page 3-1.
1. Review the Purchase Order and make a note of the range that was purchased—
Low Range, Mid Range, or High Range.
2. Set the Range switch on the Signal Conditioning board to position 4, 250ppm,
500ppm, or 2500 ppm.
3. On the Signal Conditioning board, verify that the correct Hi/Mid/Lo Selection
Jumpers are installed for the range that was purchased.
4. Turn on the analyzer. It will take approximately one to two hours to reach
temperature equilibrium, which is required for calibration.
5. Verify that the air cylinder’s pressure regulator is set to a pressure of 20 to 25
psig.
6. Establish the correct sample gas pressure:
a. Supply sample gas to rear-panel sample inlet at 15 psig.
b. Adjust the sample back pressure regulator so that the sample pressure
gauge indicates 4 psig.
7. Establish the correct zero gas pressure :
a. Supply zero gas to the rear panel sample inlet and set to 15 psig.
b. Note the reading on the sample pressure gauge. It should be the same as
in Step 7b. If not, adjust the output pressure regulator on the zero gas
cylinder as required.
xii
8. Establish the correct upscale standard gas pressure:
Supply pressure for sample, upscale standard gas and zero air must be the same. If not, the
readout will be inaccurate.
NOTE
It is the responsibility of the user to measure the efficiency of the NO2-to-NO converter during the
initial startup, and at intervals thereafter appropriate to the application—normally once a month.
NOTE
a. Supply upscale standard gas to the rear panel sample inlet.
b. Note the reading on the sample pressure gauge. It should be the same as
in Step 7b. If not, adjust the output regulator as required.
9. Do the following to perform a zero calibration:
a. Set the PPM RANGE Switch to the range to be used for sample analysis.
b. Set the front panel Range 1 potentiometer to its normal operating setting, if
known; otherwise, set the potentiometer to the middle setting—that is,
halfway between the left and the right settings.
c. Supply zero gas to the rear panel sample inlet.
d. Adjust the front panel Zero potentiometer to achieve a reading of zero on a
multimeter or recorder.
10. Do the following to perform an upscale calibration:
a. Set PPM RANGE Switch at setting appropriate to the particular span gas.
b. Supply upscale standard gas to the rear panel sample inlet.
c. Adjust front panel the Range 1 potentiometer so that a reading on a
multimeter or recorder is equal to the upscale standard gas’ known NOX
concentration.
d. Adjust R25 on the signal board so that the display value and the recorder
output are equal.
xiii
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xiv
Section 1: Description and specifications
The Model 951C NOx analyzer continuously analyzes a flowing gas
sample for nitric oxide (NO) and nitrogen dioxide (NO2). The sum of
the two concentrations is reported as NOx.
The analyzer is designed to measure NO
ranges designated as Hi, Mid, or Lo.
The analysis is based on the chemiluminescence method of NO
detection. The sample is continuously passed through a heated bed
of vitreous carbon, in which NO
present in the sample passes through the converter unchanged, and
any NO2 initially present in the sample is converted to an
approximately equivalent (95%) amount of NO.
The NO is quantitatively converted to NO2 by gas phase oxidation
with molecular ozone produced within the analyzer from air supplied
by an external cylinder. During this reaction, approximately 10% of the
NO2 molecules are elevated to an electronically excited state,
followed by immediate decay to the non excited state, accompanied
by the emission of photons. These photons are detected by a
photomultiplier tube, which in turn generates a DC current
proportional to the concentration of NOx in the sample stream. The
current is then amplified and used to drive a front panel display and to
provide potentiometric and isolated current outputs.
is reduced to NO. Any NO initially
2
using one of three sets of
x
To minimize system response time, an internal sample bypass feature
provides high velocity sample flow through the analyzer.
The case heater assembly of the Model 951C maintains the internal
temperature at approximately 50° C (122° F).
1 - 1
Instruction Manual Model 951C
748214-X DECEMBER 2013
1.1 Typical applications
The Model 951C analyzer has the following specific applications:
• Oxides of nitrogen (NOx) emissions from the combustion of
fossil fuels in:
• Vehicle engine exhaust
• Incinerators
•Boilers
• Gas appliances
• Turbine exhaust
• Nitric acid plant emissions
• Ammonia in pollution control equipment (with converter)
• Nitric oxide emissions from decaying organic material (i.e.,
landfills).
1 - 2
Model 951C Instruction Manual
DECEMBER 2013 748214-X
1.2 Specifications
Repeatability Within 0.1 ppm or ±1% of fullscale, whichever is greater
Zero/Span Drift Less than ±0.1 ppm or ±1% of fullscale, whichever is greater, in 24
hours at constant temperature
Less than ±0.2 ppm or ±2% of fullscale, whichever is greater, over any
10 C interval from 4 to 40 C (for rate change of 10 C or less per hour)
Response Time
(Electronic + Flow)
Sensitivity Less than 0.1 ppm or 1% of fullscale, whichever is greater
Detector Operating
Pressure
Total Sample Flow
Rate
Sample Pressure 138 kPa (20 psig)
Ozone Generator Gas U.S.P. breathing-grade air
Ambient Temperature
Range
Analog Output
Potentiometric 0 to +5 VDC, 2000 ohm minimum load
Isolated Current Field-selectable 0 to 20 or 4 to 20 mA, 700 ohm max load
Display Digital, 4-1/2 digit LCD, readout in engineering units, back-lighted
Power Requirements 115/230 VAC 10%, 50/60 3 Hz, 570 W maximum
Enclosure General purpose for installation in weather-protected areas
Dimensions 8.7 in. x 19.0 x 19.0 in. (H x W x D)
90% of fullscale in less than 1 minute
Atmospheric
1 Liter per minute at 20 psig
4 to 40 C (40 to 104 F)
22.0 cm x 48.3 cm x 48.3 cm (H x W x D)
Weight 22.2 kg (49 lbs) approximate
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Instruction Manual Model 951C
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748214-X DECEMBER 2013
1 - 4
Section 2: Installation
2.1 Unpacking
Carefully examine the shipping carton and contents for signs of
damage. Immediately notify the shipping carrier if the carton or its
contents are damaged. Retain the carton and packing material until
the instrument is operational.
2.2 Location
Install analyzer in a clean area, free from moisture and excessive
vibration, at a stable temperature within 4 to 40° C.
Figure 2-1. Panel Cutout / Installation Drawing
The analyzer should be mounted near the sample source to minimize
sample transport time.
2 - 1
Instruction Manual Model 951C
WARNING
748214-X DECEMBER 2013
A temperature control system maintains the internal analyzer
temperature at 50° C (122° F) to ensure proper operation over an
ambient temperature range of 4 to 40° C (40 to 104° F). Temperatures
outside these limits necessitate the use of special temperature
controlling equipment or environmental protection. Also, the ambient
temperature should not change at a rate exceeding 10° C per hour.
The cylinders of air and span gas should be located in an area of
constant ambient temperature.
2.3 Voltage requirements
ELECTRICAL SHOCK HAZARD
For safety and proper performance this instrument must be connected to a properly
grounded three-wire source of power.
This instrument was shipped from the factory pre-configured to
operate on 115 VAC, 50/60 Hz electric power.
2.3.1 Operating on 230 VAC
To operate the analyzer on 230 VAC, 50/60 Hz, do the following:
1. Set the voltage select switches (S1, S2, S3) on the Power
Supply Board and the voltage select switch (S3) on the
Temperature Control Board to the 230 VAC position.
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Figure 2-2. Power Supply Board voltage select switches
Figure 2-3. Temperature Control board voltage select switch
2. On the rear of the analyzer, replace the 6.25 A fuse with the
3.15 A fuse (P/N 898587) that is provided in the shipping kit.
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Figure 2-4. Rear view of Model 951C (cover removed)
2.4 Connecting cables
The power (PN# 899330) and recorder (PN# 899329) cable glands
are supplied in the shipping kit. To connect the appropriate cable to its
connector or terminal strip on the analyzer, do the following:
1. Remove the analyzer’s rear cover to access the terminals.
2. Route each cable through its cable gland and connect to the
appropriate connector or terminal strip.
Figure 2-5. Cable gland
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3. Tighten the glands.
2.4.1 Connecting the power cord
If this instrument is located on a bench or table top or is installed in a
protected rack, panel or cabinet, power can be connected with a 3wire flexible power cord.
The power cord must be at least 18 AWG with a maximum outside diameter (OD) of
48 inches.
To connect the power cord to the Model 951C, do the following:
1. Using the cable gland (PN# 899330) that is provided in the
installation kit, insert the power cord through the hole on the
Model 951C that is labeled POWER.
2. Connect the power cord leads to TB1 on the rear panel.
3. Tighten the cable gland adequately to prevent the rotation or
slippage of the power cable. Since the rear terminals do not
slide out with the chassis, no excess power cable slack is
necessary.
The following power cord and/or support feet are available:
• Power cord (PN# 634061), which contains a 10-foot North
American power cord set.
• Enclosure Support Kit (PN# 634958), which contains four
enclosure support feet for bench top use.
• Power Cord/Enclosure Support Kit (PN# 654008), which
contains a 10-foot North American power cord set and four
enclosure support feet.
If the instrument is permanently mounted in an open panel or rack, use electrical
metal tubing or conduit.
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2.4.2 Connecting the potentiometric recorder cables
Potentiometric recorder cables connect to the rear panel. Route the
cable through the cable gland in the hole on the Model 951C that is
labeled RECORDER OUTPUT and connect the cable’s leads to the
VOLT OUTPUT terminals.
Distance from recorder to analyzer: 1000 feet (305 meters) maximum
Input impedance: Greater than 2000 ohms
Cable (user supplied): Two conductor, shielded, min. 20 AWG
Voltage output: 0 to +5 VDC
2.4.3 Connecting the current recorder
Current recorder cables connect to the rear panel. Route the cable
through the cable gland in the hole on the Model 951C that is labeled
RECORDER OUTPUT and connect the cable’s leads to the CUR
OUTPUT terminals.
Distance from recorder to analyzer: 3000 feet (915 meters).maximum
Load resistance: Less than 700 Ohms
Cable (user supplied): Two conductor, shielded, min. 20 AWG
Voltage output: 0 to +5 VDC
2.4.4 Adjusting the current output to produce a zero of 0 mA
Do the following to adjust the current output to produce a zero of 0
mA:
1. Do the following to establish the correct zero gas pressure:
(a.) Supply zero gas to rear panel sample inlet.
(b.) Note the reading on internal sample pressure gauge. It
should be the same as the nominal 4 psig (28 kPa)
sample pressure indicated on the internal sample
pressure gauge.
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(c.) The internal sample pressure should remain constant
when the analyzer input sample is switched from a
calibration gas standard to a zero gas standard. This
can be assured by setting the delivery pressure from the
sample gas cylinder and the zero gas cylinder equal to
the delivery pressure of the span gas cylinder, which is
20 psig (138 kPa). If this cannot be accomplished,
adjust the output pressure regulator on the zero gas
cylinder as required.
2. Adjust R23, the zero adjust potentiometer on the power supply
board, to produce 0 mA current output.
2.5 Gas requirements
The instrument requires two gases normally supplied from cylinders:
air and span gas.
2.5.1 Air (U.S.P. Breathing Grade)
Air is used as both an oxygen source for the generation of the ozone
required for the chemiluminescence reaction, and as a standard gas
for zero calibration. Air for each purpose must be supplied from a
separate cylinder due to the different pressure requirements at the
ozonator and the zero inlets.
2.5.2 Span Gas
Span gas is a standard gas of accurately known composition that is
used to set an upscale calibration point. The usual span gas is NO or
NO
in a background of nitrogen.
2
HIGH PRESSURE GAS CYLINDERS
The Model 951C requires periodic calibration with a span gas. “Calibrating the
analyzer” on page 3-10. See also General Precautions for Handling and Storing
High Pressure Gas Cylinders, page P-5.
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For maximum calibration accuracy, the concentration of nitrogen oxide in the span
gas should be similar to that in the sample gas. Also, the span gas should be
supplied to the Model 951C’s rear panel sample inlet at the same pressure as the
sample gas. To ensure constant pressure, use a pressure regulator immediately
upstream from the sample inlet.
Each span gas used should be supplied from a tank or cylinder
equipped with a clean, noncorrosive, two-stage regulator. In addition,
a shut off valve is recommended.
Install the gas cylinders in an area of relatively constant ambient
temperature.
2.5.3 Sample requirements
The sample gas must be clean and dry before entering the analyzer.
In general, the sample should be filtered to eliminate particles larger
than two microns and should have a dew point below 90° F (32° C).
Proper supply pressure for sample, zero and span gases for the Model 951C is 20
psig (138 kPa).
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2.5.4 Connecting gas
TOXIC AND OXIDIZING GAS HAZARDS
This instrument generates ozone which is toxic by inhalation and is a strong irritant
to throat and lungs. Ozone is also a strong oxidizing agent. Its presence is detected
by a characteristic pungent odor.
The instrument exhaust contains both ozone and nitrogen dioxide, both toxic by
inhalation, and may contain other constituents of the sample gas which may be
toxic. Such gases include various oxides of nitrogen, unburned hydrocarbons,
carbon monoxide and other products of combustion reactions. Carbon monoxide is
highly toxic and can cause headache, nausea, loss of consciousness, and death.
Avoid inhalation of the ozone produced within the analyzer and avoid inhalation of
the sample and exhaust products transported within the analyzer. Avoid inhalation
of the combined exhaust products at the exhaust fitting.
Keep all tube fittings tight to avoid leaks. See Section 2-8 for Leak Test Procedure.
Connect rear exhaust outlet to outside vent by a 1/4 inch (6.3 mm) or larger
stainless steel or Teflon line. Check vent line and connections for leakage.
To connect a gas to the Model 951C, do the following:
1. Remove plugs and caps from all inlet and outlet fittings.
2. Connect the exhaust outlet to the external vent with stainless
steel or teflon tubing that has an outside diameter of at least
.25 inches (6.3 mm).
3. Connect the external lines from the ozonator air and sample
sources to the corresponding rear panel inlet ports. For sample
line, stainless steel tubing is recommended.
4. Adjust the regulator on the ozonator air cylinder to an output
pressure of 20 to 25 psig (138 to 172 kPa). At least 20 psig
should be present at the rear of the analyzer.
5. Supply sample gas to the rear panel sample inlet at
appropriate pressure: 20 psig (138 kPa).
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