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Model 9110T NOx Analyzer EPA Protocol Calibration
Teledyne Analytical Instruments 223
10.2.2. CALIBRATION GAS AND ZERO AIR SOURCES
10.2.2.1. Zero Air
Devices that condition ambient air by drying and removal of pollutants are available on the commercial
market such as the Teledyne M701 zero air generator.
10.2.2.2. Span Gas
NO and NO
x
calibration gases supplied either directly from pressurized bottles of calibrated gas of
different concentrations (see Table 3-8 or from a single source of high concentration gas then mixed to
create various lower concentrations. In the latter case, we recommend using a gas dilution calibrator
such as a Teledyne M700E.
In ALL cases, the gases and instrument(s) used must be calibrated and that calibration must be traceable
to an EPA/NIST primary standard.
10.2.3. DATA RECORDING DEVICE
Either a strip chart recorder, data acquisition system, digital data acquisition system should be used to
record the data from the 9110T RS-232 port or analog outputs. If analog readings are being used, the
response of that system should be checked against a NIST referenced voltage source or meter. Data
recording device should be capable of bi-polar operation so that negative readings can be recorded. Strip
chart recorder should be at least 6” (15 cm) wide.
10.2.4. RECORD KEEPING
Record keeping is a critical part of all quality assurance programs. Standard forms similar to those that
appear in this manual should be developed for individual programs. Three things to consider in the
development of record forms are:
Does the form serve a necessary function?
Is the documentation complete?
Will the forms be filed in such a manner that they can easily be retrieved when needed?
10.3. CALIBRATION FREQUENCY
A system of Level 1 and Level 2 zero/span checks is recommended (see Section 10.4). Level 1 zero and
span checks should be conducted at least every two weeks. Level 2 checks should be conducted in
between the Level 1 checks at a frequency determined by the user. Span concentrations for both levels
should be between 70 and 90% of the reporting range.
To ensure accurate measurements of the NO, NO
X
, and NO
2
concentrations, calibrate the analyzer at the
time of installation, and recalibrate it:
No later than three months after the most recent calibration or performance audit that indicated the
analyzer calibration to be acceptable.
An interruption of more than a few days in analyzer operation.