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M400E Ozone Analyzer Operator’s Manual 346BEPA Protocol Calibration
10.4.3. SYSTEM AUDIT
A system audit is an on-site inspection and review of the quality assurance activities used for the total
measurement system (sample collection, sample analysis, data processing, etc.); it is a qualitative appraisal of
system quality.
Conduct the system audit at the startup of a new monitoring system and periodically (as appropriate) as
significant changes in system operations occur.
The recommended audit schedule depends on the purpose for which the monitoring data are being collected.
For example, Appendix A, 40 CFR 58
8
requires that each analyzer in State and Local Air Monitoring Networks
(SLAMS) be audited at least once a year. Each agency must audit 25% of the reference or equivalent analyzers
each quarter. If an agency operates less than four reference or equivalent analyzers, it must randomly select
analyzers for re-auditing so that one analyzer will be audited each calendar quarter and so that each analyzer
will be audited at least once a year.
Appendix B, 40 CFR 58
9
requires that each PSD (prevention of significant deterioration) reference or equivalent
analyzer be audited at least once a sampling quarter. Results of these audits are used to estimate the accuracy
of ambient air data.
10.4.4. ASSESSMENT OF MONITORING DATA FOR PRECISION AND
ACCURACY
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 O
3
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. Those standards used
for calibration or auditing may be used.
Estimates of single instrument accuracy for ambient air quality measurements from continuous methods are
calculated according to the procedure in Appendix 15 of the Q.A. Handbook (Reference 11).
10.5. SUMMARY OF QUALITY ASSURANCE CHECKS
Essential to quality assurance are scheduled checks for verifying the operational status of the monitoring
system. The operator should visit the site at least once each week. Every two weeks a Level 1 zero and span
check must be made on the analyzer. Level 2 zero and span checks should be conducted at a frequency
desired by the user.
In addition, an independent precision check between 0.08 and 0.10 ppm may be required at least once every
two weeks.
04315 Rev. C1 181