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Teledyne API Model 200AU NO
X
Analyzer Instruction Manual, 02293, Rev. F
7-31
Table 7-17: NIST-SRM's Available for Traceability of Calibration and Audit Gas
Standards
NIST-SRM
4
Type Size, at STP
Nominal
Concentration
1683a
1684a
1685a
Nitric oxide in N
2
Nitric oxide in N
2
Nitric oxide in N
2
870
870
870
50 ppm
100 ppm
250 ppm
Permeation Tubes
NIST-SRM
4
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 NO
2
standards. Any NO
2
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 NO
2
impurity in the NO cylinder,
[NO
2
]
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.