Teledyne API Model 200AU NOX Analyzer Instruction Manual, 02293, Rev. F
7-31
Table 7-17: NIST-SRM's Available for Traceability of Calibration and Audit Gas
Standards
NIST-SRM4 Type Size, at STP Nominal
Concentration
1683a
1684a
1685a
Nitric oxide in N2
Nitric oxide in N2
Nitric oxide in N2
870
870
870
50 ppm
100 ppm
250 ppm
Permeation Tubes
NIST-SRM4 Type Permeation rate,
ug/min
Concentration, ppm
at flow rates of:
1 L/min/5 L/min
1629 Nitrogen dioxide 1.0 0.5/0.1
Cylinders of working gas traceable to NIST-SRM's (called EPA Protocol Calibration Gas) are
also commercially available (from sources such as Scott Specialty Gases, Scott-Marin etc.).
7.6.12 Certification Procedures of Working Standards The NO content of the NO working standard must be periodically assayed against NIST-traceable
NO or NO2 standards. Any NO2 impurity in the cylinder must also be assayed. Certification of the
NO working standard should be made on a quarterly basis or more frequently, as required.
Procedures are outlined below for certification against NO traceable standard. The simplest and most
straightforward procedure is to certify against a NO standard.
NOTE
If the assayed concentration of NO2 impurity in the NO cylinder,
[NO2]imp, is greater than the 1 ppm value allowed in the calibration
procedure, make certain that the NO delivery system is not the
source of contamination before discarding the NO standard.