Teledyne 9110T Certification of Working Standards, Precision Check Procedure

Model 9110T NOx Analyzer EPA Protocol Calibration

∙Zero/Span checks through remote contact closure can be initiated through remote contact closures on the rear panel. See Section 9.4.3.3 of this manual.

∙Zero/span checks can also be controlled through the RS-232 port. See Section 8 of this manual for more details on setting up and using the analyzer’s RS-232 port.

10.8.4. PRECISION CHECK

A periodic check is used to assess the data for precision. A one-point precision check must be carried out at least once every 2 weeks on each analyzer at an NO2 concentration between 0.08 and 0.10 ppm.

∙The analyzer must be operated in its normal sampling mode, and the precision test gas must pass through all filters, scrubbers, conditioners, and other components used during normal ambient sampling.

∙The standards from which precision check test concentrations are obtained must be traceable to NIST-SRM SRM. Those standards used for calibration or auditing may be used.

10.8.4.1. Precision Check Procedure

Connect the analyzer to a precision gas that has an NO2 concentration between 0.08 and 0.10 ppm. An NO2 precision gas may be generated by either GPT or a NO2 permeation tube. If a precision check is made in conjunction with a zero/span check, it must be made prior to any zero or span adjustments.

∙Allow the analyzer to sample the precision gas until a stable trace is obtained.

∙Record this value.

∙NO and NOX precision checks should also be made if those data are being reported. Information from the check procedure is used to assess the precision of the monitoring data; see in Section 12 of the Q.A. Handbook6 for procedures for calculating and reporting precision.

10.9.CERTIFICATION 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 which is the simplest and most straightforward procedure.

To assure data of desired quality, two considerations are essential:

∙The measurement process must be in statistical control at the time of the measurement and;

∙Any systematic errors, when combined with the random variation in the measurement process, must result in a suitably small uncertainty.

Evidence of good quality data includes documentation of the quality control checks and the independent audits of the measurement process by recording data on specific forms or on a quality control chart and by using materials, instruments, and measurement procedures that can be traced to appropriate standards of reference.

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