M-20 Operation And Maintenance Manual
83550-003-001 Revision C
2008-01-03
15
Item
Name
Item Range
Default
Description/Function
“Span Cal”
2500ppm ± 50ppm
2500ppm
NOTE:
Please refer to the
Calibration
section in
the text
below for more information.
EXCEPTION:
It is also possible to calibrate the span
with a different span gas concentration
than 2500ppm. In such cases, replace
2500ppm in this procedure with the
chosen span gas concentration (e.g.:
5000ppm). The unit will have non-linear
response for span calibration above
5000ppm.
PROCEDURE:
1) Apply 2500ppm CO
2
(balance
Nitrogen) to the unit, using an M-20
calibration kit.
2) Press Enter and see the * appear on
the bottom LCD line.
3) Wait for the concentration to stabilize,
it should be 2500ppm ± 1000ppm.
4) Press Dn (or Up) to set the indicated
concentration to 2500ppm ± 50ppm.
As you get closer to 2500ppm, reduce
the number of Up or Dn key presses
between measurements.
5) If the concentration changes and re-
stabilize more than 50ppm from
2500ppm, press Up or Dn to trim the
concentration.
6) Repeat step 5) until the concentration
shows a stable pattern between
2450pm and 2550ppm.
7) Press Enter to accept (* disappears).
