RKI Instruments M2A Operator's Manual page 9

Junction Box
The M2A's cast aluminum junction box is dust and weather resistant. The junction box also protects the M2A
and all connections made to it. Use the three 3/4 NPT conduit ports to mount the detector to the junction box
(factory installed in the bottom port) and connect wiring from an external device (left port). The top port is
shipped with a factory installed and sealed conduit plug to avoid leaks into the junction box. If necessary, the
conduit plug can be removed and the top port can be used for wiring.
WARNING:
Use the junction box's two mounting holes to mount the M2A to a vertical surface at the monitoring site. The
window in the cover on the front of the junction box allows you to view the OLED display and use the magnetic
wand to actuate the magnetic control switches so you can perform non-intrusive calibration. Removing the cover
allows you to access the interior of the junction box.
Magnetic Wand
The magnetic wand is a short plastic rod with a magnet in one end. It is used to actuate the magnetic control
switches on the control PCB while the junction box cover is still installed so that non-intrusive calibration can be
performed.
Gas Detector
The gas detector senses the target gas and is mounted in a 3/4 NPT conduit port on the right bottom side of the
M2A. The IR combustible detectors are generally used instead of the catalytic combustible detectors in
applications where there may be catalyst poisons such as silicone present or where oxygen is not present in the
monitoring environment.
The IR detector has a replaceable plug-in sensor inside the detector housing. A sensor gasket seals the sensor
face to the detector housing cap.
M2A Transmitter Operator's Manual
If the top conduit port is used for wiring, be sure to seal the threads to ensure water does not
enter the junction box. See "Wiring the M2A Transmitter" on page 15 for complete wiring
instructions.
Detector Housing Body
Figure 2: Detector Component Location
Cap Gasket
Plug-In IR Sensor
Detector Housing Cap
Flame Arrestor
Guard
9