RKI Instruments M2A - Manual (Page 47)

M2A Transmitter Operator’s Manual 42
Calibration, Combustible Gas, CO
2
, and Toxic Versions
This section describes how to calibrate the combustible gas, CO
2
, and toxic gas versions of the
M2A. 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. See the next section,
“Calibration, Oxygen Version” for instructions to calibrate an oxygen M2A.
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.
Preparing for Calibration
NOTE: The following procedure assumes the use of a calibration kit which includes a
calibration gas cylinder, a zero air cylinder, a fixed flow regulator with an on/off knob,
a calibration cup for the appropriate sensor, and a short piece of sample tubing to
connect the regulator to the calibration cup.
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 31 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 (span
for oxygen) reading.
1. Connect the calibration kit sample tubing to the calibration cup hose barb.
2. Screw the calibration cup onto the detector.
NOTE: For an ESM-01 detector, you must unscrew the removable splashguard from the
detector housing cap so you can push the appropriate calibration cup onto the ESM-01
sensor. Make sure to use the correct calibration cup for the sensor being used. There is a
Cl
2
type calibration cup for a Cl
2
sensor, an NH
3
type calibration cup for an NH
3
sensor, and a general type (usually labeled SO
2
) calibration cup for all other ESM-01
sensors.
3. Connect the fixed flow regulator to the calibration cup using the sample tubing.
NOTE: When calibrating an NH
3
ESM-01, the 0.25 LPM flowrate regulator must be used. All
other M2As require a 0.5 LPM flowrate regulator.