Teledyne 6200A Manual page 127

TAI Model 6200A SO
Table 7-13: Definition of Level 1 and Level 2 Zero and Span Checks
(from Section 2.0.9 of Q.A. Handbook for Air Pollution Measurement Systems)
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
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.
Analyzer Operator Manual, 02164, Rev. G
2
are easily automated.
7-20
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
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
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.
with uncertified test
is accurately known.