Zero And Span Checks; Table 8-4: Definition Of Level 1 And Level 2 Zero And Span Checks - Teledyne 100E Instruction Manual

EPA Protocol Calibration
In addition, an independent precision check between 0.08 and 0.10 ppm must be carried
out at least once every two weeks. Table 8-3 summarizes the quality assurance activities
for routine operations. A discussion of each activity appears in the following sections.
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 8-4: 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 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.

8.3. ZERO and SPAN Checks

A system of Level 1 and Level 2 zero span checks (see Table 8-4) is recommended. These
checks must be conducted in accordance with the specific guidance given in Subsection
9.1 of Section 2.0.9 (Q.A. Handbook). It is recommended Level 1 zero and span checks
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Model 100E Instruction Manual
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.
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