54
M2A Transmitter Operator’s Manual
Calibration, Oxygen Version
This section describes how to calibrate the oxygen version of the M2A. It includes procedures to prepare for
calibration, enter Calibration Mode, set the fresh air (span) reading, set the zero reading, and return to normal
operation.
NOTE:
An O
2
detector must be calibrated with 0 - 18% O
2
.
WARNING:
The M2A is not an active gas monitoring device during the calibration procedure. The 4-20
mA output signal will “freeze” at 17.4 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.
Preparing for Calibration
NOTE:
The following procedure assumes the use of a calibration kit which includes a zero air (20.9%
oxygen) calibration cylinder to set the fresh air reading, a 100% nitrogen (0% oxygen) calibration gas
cylinder to set the zero reading, a fixed flow regulator with an on/off knob, a calibration cup, and a
short piece of sample tubing to connect the regulator to the calibration cup. A cylinder with up to an
18% oxygen concentration may be used instead of a 100% nitrogen cylinder to set the zero reading.
NOTE:
While in calibration mode, 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 42 for
instructions to set the calibration time-out.
NOTE:
The following procedure assumes that the oxygen concentration in the calibration area is not normal,
20.9%, but is oxygen deficient. If a fresh air environment can be verified, applying zero air to the
detector is not necessary when adjusting the fresh air (span) setting.
1. Connect the calibration kit sample tubing to the calibration cup hose barb.
2. Screw the calibration cup onto the detector.
3. Connect the fixed flow regulator to the calibration cup using the sample tubing.
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 or zero adjustment procedure. This feature enables one person to perform a
calibration if the detector is mounted remotely from the M2A. When zero air is applied to the M2A during a fresh
www.
.com
1.800.561.8187