ACOEM Met One Instruments GAS-1060, Руководство пользователя

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Calibration Page 95
5.6 Precision Check
Similar to a normal zero or span calibration, a precision check is a Level 2 calibration that may be
performed using a non-certified reference. The instrument is supplied with a known concentration of
span gas (or zero air) and the instrument’s response observed. However, no adjustment to the
instrument response is made during a precision check.
Note: Ensure that the instrument has been running for at least one hour before any calibration is
performed to ensure the instrument’s stability.
A precision check can be performed either manually via the Sample Port or Calibration Port or can
also be performed automatically using the Timed Mode (refer to Section 3.4.10.2).
Procedure
1. Supply the instrument with a zero source (refer to Section 5.4 for the procedure of setting up a
zero, but do not do a
Zero Calibrate NO2 ).
2. Observe and record the measurement from the instrument.
3. Supply the instrument with a span source (refer to Section 5.5 for the procedure of setting up a
span but do not do a
Span Calibrate NO2 ).
4. Observe and record the measurement from the instrument.
5. Check both readings against your local applicable standards.
If an instrument fails a span precision check (based on the users local applicable standards), perform
a span calibration (refer to Section 5.5).
If an instrument fails a zero precision check (based on the users local applicable standards), resolve
the issue by referring to Section 7.
5.7 Multipoint Precision Check
A multipoint precision check is used to determine the linear response of the instrument across its
operating range. The instrument is supplied with span gas at multiple known concentrations,
typically a zero point and at least four up-scale points, spread across the operating range of the
instrument. The observed concentrations are compared to expected values and the linearity of the
instrument assessed against local applicable standards.
Note: The instrument is inherently linear and the instrument gain should not be adjusted at each
individual point. Non-linearity indicates a problem with the instrument or calibration system (refer to
Section 7). Ensure that the instrument has been running for at least one hour before any calibration
is performed to ensure the instrument’s stability.
Several methods for producing multiple known concentrations are available to use, such as
connecting multiple certified gas cylinders at different concentrations. However, Ecotech strongly