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Model 9110T NOx Analyzer Calibration Procedures
Teledyne Analytical Instruments 196
The same applies to gases that contain high concentrations of other compounds (for example, CO
2
or H
2
O).
Note The span gas should match all concentrations of all gases of the
measured medium as closely as possible.
Cylinders of calibrated NO
x
and NO gas traceable to NIST-standards specifications (also referred to as EPA
protocol calibration gases or Standard Reference Materials) are commercially available. For a list of these
gases see Table 3-8).
9.1.2.3. Span Gas for Multipoint Calibration
Some applications, such as EPA monitoring, require a multipoint calibration where span gases of
different concentrations are needed. We recommend using an NO gas of higher concentration combined
with a gas dilution calibrator such as a Teledyne Model T700. For more information see Section 3.3.2.1
and Section 10.
9.1.2.4. NO
2
Permeation Tubes
TAI offers an optional internal span gas generator that utilizes an NO
2
permeation tube as a span gas
source. The accuracy of these devices is only about ±5%.
Whereas this may be sufficient for quick, daily calibration checks, we recommend using certified NO
gases for accurate calibration.
Note The use of permeation tubes is not approved by the US EPA as calibration
sources for performing actual calibration of the analyzers used in EPA
mandated monitoring.
CAUTION!
Insufficient gas flow allows gas to build up to levels that will contaminate
the instrument or present a safety hazard to personnel.
In units with a permeation tube option installed, either the tube must be
removed and stored in sealed container (use original container that tube
was shipped in) during periods of non-operation, or vacuum pump must
be connected and powered on to maintain constant gas flow though the
analyzer at all times.
(See Figure 3-6 for location and Section 11.3.6 for instructions on how to remove the
perm tube when the unit is not in operation).
9.1.3. DATA RECORDING DEVICES
A strip chart recorder, data acquisition system or digital data acquisition system should be used to record
data from the serial or analog outputs of the 9110T.
If analog readings are used, the response of the recording system should be checked against a
NIST traceable voltage source or meter.