Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 45)

Getting Started Model 9110TH NOx Analyzer
Teledyne Analytical Instruments 25
Even though NO gas in nitrogen could be used as a span gas, the matrix of the balance
gas is different and may cause interference problems or yield incorrect calibrations. The
same applies to gases that contain high concentrations of other compounds (for example,
CO
2
or H
2
O). The span gas should match all concentrations of all gases of the measured
medium as closely as possible.
Cylinders of calibrated NO gas traceable to NIST-standard reference materials
specifications (also referred to as EPA protocol calibration gases) are commercially
available.
Table 3-9: NIST-SRM's Available for Traceability of NO
x
Calibration Gases
NIST-SRM 4 TYPE
NOMINAL
CONCENTRATION
2627a
2628a
2629a Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
5 ppm
10 ppm
20 ppm
1683b
1684b
1685b
1686b
1687b Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
50 ppm
100 ppm
250 ppm
5000 ppm
1000 ppm
2630
2631a
2635
2636a
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
Nitric Oxide (NO) in N
2
1500 ppm
3000 ppm
800 ppm
2000 ppm
2631a
1684b Oxides of Nitrogen (NO
x
) in N
2
Oxides of Nitrogen (NO
x
) in N
2
3000 ppm
100 ppm
Note If a dynamic dilution system such as the TAI Model T700 is used to dilute
high concentration gas standards to low, ambient concentrations, make
sure that the NO concentration of the reference gas matches the dilution
range of the calibrator. Choose an NO gas concentration that is in the
middle of the dilution system’s range.