Teledyne M300EM operation manual Zero And Span Checks, Q.A. Handbook1 Vol II, Part1, .3

Teledyne API – Technical Manual - Model 300E Family CO Analyzers EPA Calibration Protocol

Table 10-3: Definition of Level 1 and Level 2 Zero and Span Checks

(Q.A. Handbook1 Vol II, Part1, Section 12.3 & 12.4)

LEVEL 1 ZERO AND SPAN CALIBRATION

A Level 1 zero and span calibration is a simplified, two- point analyzer calibration used when analyzer linearity does not need to be checked or verified. (Sometimes when no adjustments are made to the analyzer, the Level 1 calibration may be called a zero/span check, in which case it must not be confused with a Level 2 zero/span check.) Since most analyzers have a reliably linear or near-linear output response with concentration, they can be adequately calibrated with only two concentration standards (two-point concentration). Furthermore, one of the standards may be zero concentration, which is relatively easily obtained and need not be certified. Hence, only one certified concentration standard is needed for the two-point (Level

1)zero and span calibration. Although lacking the advantages of the multipoint calibration, the two-point zero and span calibration--because of its simplicity--can be (and should be) carried out much more frequently. Also, two-point calibrations are easily automated. Frequency checks or updating of the calibration relationship with a two-point zero and span calibration improves the quality of the monitoring data by helping to keep the calibration relationship more closely matched to any changes (drifts) in the analyzer response.

LEVEL 2 ZERO AND SPAN CHECK

A Level 2 zero and span check is an "unofficial" check of an analyzer's response. It may include dynamic checks made with uncertified test concentrations, artificial stimulation of the analyzer's detector, electronic or other types of checks of a portion of the analyzer, etc.

Level 2 zero and span checks are not to be used as a basis for analyzer zero or span adjustments, calibration updates, or adjustment of ambient data. They are intended as quick, convenient checks to be used between zero and span calibrations to check for possible analyzer malfunction or calibration drift. Whenever a Level 2 zero or span check indicates a possible calibration problem, a Level 1 zero and span (or multipoint) calibration should be carried out before any corrective action is taken.

If a Level 2 zero and span check is to be used in the quality control program, a "reference response" for the check should be obtained immediately following a zero and span (or multipoint) calibration while the analyzer's calibration is accurately known. Subsequent Level 2 check responses should then be compared to the most recent reference response to determine if a change in response has occurred. For automatic Level 2 zero and span checks, the first scheduled check following the calibration should be used for the reference response. It should be kept in mind that any Level 2 check that involves only part of the analyzer's system cannot provide information about the portions of the system not checked and therefore cannot be used as a verification of the overall analyzer calibration.

10.2.ZERO AND SPAN CHECKS

A system of Level 1 and Level 2 zero span checks is recommended. These checks must be conducted in accordance with the specific guidance given in Section 12 of the QA Handbook Vol II Part 11. It is recommended that Level 1 zero and span checks be conducted every two weeks. Level 2 checks should be conducted in between the Level 1 checks at a frequency desired by the user. Span concentrations for both levels should be between 70 and 90% of the measurement range.

Zero and span data are to be used to:

1.Provide data to allow analyzer adjustment for zero and span drift;

2.Provide a decision point on when to calibrate the analyzer;

3.Provide a decision point on invalidation of monitoring data.

Items 1 and 2 are described in detail in Subsection 9.1.3 of Section 2.0.9 (Q.A. Handbook Vol II4). Item 3 is described in Subsection 9.1.4 of the same section.

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