65-2670XL-XX-07 M2A-XL Transmitter
Chapter 7: Maintenance
•
41
Calibration
This section describes how to calibrate the M2A-XL transmitter. It includes procedures to prepare
for calibration, enter Calibration Mode, adjust the fresh air (zero) setting, adjust the span setting,
and return to normal operation.
WARNING: The M2A-XL is not an active gas monitoring device during the calibration
procedure. The 4-20 mA output signal will “freeze” at 3.5 mA and all relays will
remain in their non-alarm state while the M2A-XL is in Calibration Mode. The
output signal will not indicate current readings and the relays will not resume
operating normally until the M2A-XL is in normal operation again.
NOTE:
The detector must be calibrated with a gas concentration between 10% and 100% of the
channel’s full scale value (ie. a 0 - 500 ppm NH
3
detector must be calibrated with an
NH
3
concentration between 50 ppm and 500 ppm).
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-XL
Parameters” on page 31 for instructions to set the calibration time-out.
Special Note About Calibrating a ClO
2
Detector
There are two ways to calibrate a ClO
2
detector: using a ClO
2
generator or using a Cl
2
cylinder
and a 0.4 factor.
• If a Cl
2
cylinder is used for calibration, RKI Instruments, Inc. recommends using 2 ppm of
Cl
2
and setting the ClO
2
reading to 0.8 ppm.
• If a ClO
2
generator is being used, the generator’s flow rate should be set to 0.5 LPM.
RKI Instruments, Inc. recommends that 0.5 ppm ClO
2
be used. The steps related to use of
a calibration gas cylinder in the following instructions can be disregarded.
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.
