65-2661RK-XX-04 M2A Transmitter Operator’s Manual
37
7. Turn the regulator’s on/off knob clockwise to close the regulator.
8. Unscrew the regulator from the calibration cylinder.
9. Disconnect the calibration adapter/splash guard’s flexible tubing from the regulator.
NOTE:
Do not disconnect the flexible tubing from the calibration adapter/splash guard.
10. Add 1 minute to the length of time determined in step 6. This is the response time for the detector. When
performing a zero adjustment or span adjustment, gas must be applied for this length of time.
Calibration
This section describes how to calibrate the M2A 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 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 is in Calibration Mode. The output signal will not indicate current readings
and the relays will not resume operating normally until the M2A is in normal operation
again.
NOTE:
The following procedure assumes the use of a calibration kit which includes a calibration gas
cylinder, a 100% N
2
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. a 0 - 5,000 ppm CO
2
detector must be calibrated with a CO
2
concentration
between 500 and 5,000 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 Parameters” on page 28 for
instructions to set the calibration time-out.
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
