Level 1 Calibrations Versus Level 2 Checks - Teledyne 400E Instruction Manual

Model 400E Ozone Analyzer
Instruction Manual

8.2. Level 1 Calibrations versus Level 2 Checks

All monitoring instruments are subject to some drift and variation in internal
parameters and cannot be expected to maintain accurate calibration over long
periods of time the EPA requires a schedule of periodic checks of the analyzer's
calibration be implemented. Zero and span checks must be used to document that
the data remains within required limits. These checks are also used in data
reduction and system validation.
A Level 1 Span check is used to document that the M400E is within control limits
and must be conducted every 2 weeks. A Level 2 Span Check is to be conducted
between the Level 1 Checks on a schedule to be determined by the user.
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 r esponse. 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.
P/N 04316 Rev: B
(Section 12 of Q.A. Handbook)
(Section 12 of Q.A. Handbook)
EPA Protocol Calibration
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