Thermo Scientific 42iQLS, Instruction Manual

Page: 186 / 318

Calibration
Zero and Span Check
4-20 42iQLS Instruction Manual Thermo Scientific
2. Press the Back button to return to the Calibration menu and choose
Calibrate High Range NO
2
Span Coefficient .
The user sets the span concentration by pressing the Edit Span
Concentration button. The New NO
2
Span Coefficient button will
show what the span coefficient will be set to if the Calibrate button is
pressed.
3. Set the high NO
2
calibration gas concentration to reflect the sum of the
NO
2
concentration generated by GPT and any NO
2
impurity using the
pushbuttons, and then press Calibrate to calculate and save the new
high range NO
2
span coefficient based on the entered span coefficient.
The analyzer requires initial and periodic calibration according to the
procedures outlined in this manual. Initially, the frequency of the
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 42iQLS
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
2
, and NO
x
channels then record the zero
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
Zero and Span
Check