Teledyne GFC7001T User Manual download pdf (Page 230)

EPA Calibration Protocol Teledyne API – Model T300/T300M CO Analyzer

Teledyne Analytical Instruments 230

weeks. Level 2 zero and span checks should be conducted at a frequency desired by the

user. Definitions of these terms are given in Table 10-3.

To provide for documentation and accountability of activities, a checklist should be

compiled and then filled out by the field operator as each activity is completed.

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

(Q.A. Handbook

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 1

. 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:

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

 Provide a decision point on when to calibrate the analyzer;

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Teledyne GFC7001T User Manual Page 230

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