65-2646XL-05-04 M2A Transmitter Operator’s Manual
Chapter 7: Maintenance
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42
NOTE:
The following procedure assumes the use of a calibration kit which includes a
calibration gas cylinder, a zero air cylinder and a fixed flow regulator with an on/off
knob.
NOTE:
The detector must be calibrated with a gas concentration between 10% and 100% of the
channel’s full scale value (ie. between 30 ppm and 300 ppm CO).
NOTE:
While in the calibration program, if there is no switch activity for the calibration time-
out period the unit will return to normal operation. See “Viewing & Changing M2A
Parameters” on page 30 for instructions to set the calibration time-out.
NOTE:
The following procedure assumes that the target gas is present in a high enough
concentration to affect the fresh air (zero) reading. If a fresh air environment can be
verified, applying zero air to the detector is not necessary when setting the zero reading.
Non-Intrusive Calibration
If the M2A is installed in a classified area and non-intrusive calibration is required, follow the
instructions below, but do not remove the junction box cover. Use the magnetic wand accessory to
actuate the magnetic switches instead of pushing the control switch buttons. To actuate a magnetic
switch and perform the same operation as pressing a control switch button, touch the magnet in
the end of the magnetic wand to the M2A’s glass cover directly above the magnetic switch you
wish to actuate. Touching the glass and removing the wand is the same as pressing and releasing a
button. Touching the glass and keeping the wand in place is the same as pressing and holding a
button.
Calibration Gas Response Memory Feature
The M2A has the capability to “remember” the detector’s response to the calibration gas after the
gas is removed from the detector during the fresh air and span adjustment procedure. This feature
enables one person to perform calibration if the detector is mounted remotely from the M2A.
When zero air is applied to the M2A during a fresh air adjustment, the M2A will freeze the
display reading at the lowest response and the M2A will continue to display this reading and
retain it in its memory until the fresh air adjustment procedure is completed. When calibration gas
is applied to the M2A during a span adjustment, the M2A will freeze the display reading at the
highest response to the calibration gas. The calibration gas can then be removed and the M2A will
continue to display this reading and retain it in its memory until the span adjustment procedure is
completed.
