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Calibration
Zero and Span Check
Zero and Span
4-20
42iQHL Instruction Manual
2. Press the Back button to return to the Calibration menu and choose
Calibrate High Range NO
The user sets the span concentration by pressing the Edit Span
Concentration button. The New NO
show what the span coefficient will be set to if the Calibrate button is
pressed.
3. Set the high NO
NO
2
pushbuttons, and then press Calibrate to calculate and save the new
high range NO
The analyzer requires initial and periodic calibration according to the
procedures outlined in this manual. Initially, the frequency of the
Check
calibration procedure should be determined by the stability of the zero and
span checks, which may be run daily. You should generate a new
calibration curve when zero and span checks indicate a shift in instrument
gain of more than 10 percent from that determined during the most recent
multipoint calibration. You can adjust the frequency of calibration and
even zero and span checks appropriately as you gain confidence with the
instrument.
It is recommended to have a quality control plan where the frequency and
the number of points required for calibration can be modified on the basis
of calibration and zero and span check data collected over a period of time.
Note however, that the EPA requires a minimum of one multipoint
calibration per calendar quarter. Such a quality control program is essential
to ascertain the accuracy and reliability of the air quality data collected and
to alert the user if the accuracy or reliability of the data should become
unacceptable. A compilation of this kind might include items such as dates
of calibration, atmospheric conditions, calibration factors, and other
pertinent data.
Use the following procedure to perform a zero and span check.
1. Connect the zero gas to the SAMPLE bulkhead in a standard
instrument or to the ZERO IN bulkhead in a 42iQHL equipped with
the zero/span and sample solenoid valve option.
2. Allow the instrument to sample zero gas until a stable reading is
obtained on the NO, NO
readings. Unless the zero has changed by more than ±0.010 ppm, it is
recommended that the zero not be adjusted. If an adjustment larger
2
calibration gas concentration to reflect the sum of the
2
concentration generated by GPT and any NO
span coefficient based on the entered span coefficient.
2
, and NO
2
Span Coefficient.
Span Coefficient button will
2
channels then record the zero
x
impurity using the
2
Thermo Scientific
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