65-2658XL-CH4-4 M2A-XL Transmitter Operator’s Manual
Chapter 7: Maintenance
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39
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 (span
for oxygen) reading.
Non-Intrusive Calibration
If the M2A-XL 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-XL’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-XL 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 a calibration if the detector is mounted remotely from the
M2A-XL. When zero air is applied to the M2A-XL during a fresh air adjustment, the M2A-XL
will freeze the display reading at the lowest response and the M2A-XL 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-XL during a span adjustment, the M2A-XL will
freeze the display reading at the highest response to the calibration gas. The calibration gas can
then be removed and the M2A-XL will continue to display this reading and retain it in its memory
until the span adjustment procedure is completed.
Adjusting the Fresh Air Reading
1. While in normal operation, press and hold the UP/YES button for 5 seconds to enter
Calibration Mode. Release the button when the following screen appears.
2. If you want to continue with calibration, press and release the UP/YES button. The display
will indicate the target gas and
CAL Mode
for a few seconds before showing
FreshAir
Adjust?
.
If you want to exit Calibration Mode, press and release the DOWN/NO button. The M2A-
XL will indicate
Leaving CAL Mode
and the M2A-XL will return to normal operation.
3. To continue with adjusting the fresh air reading, press and release the UP/YES button.
ENTER
will alternate with
FreshAir
on the top display line and the current gas reading will
be on the bottom display line.
To skip adjusting the fresh air reading, press and release the DOWN/NO button. The
display will indicate
SPAN w/Cal Gas?
. Skip to the next section, Adjusting the Span
Calib?
YES/NO
