RKI Instruments 65-2649RK-HC-04 - Manual (Page 9)

65-2649RK-HC-04 M2A Transmitter Operator’s Manual 4
M2A Junction Box
The M2A’s cast aluminum junction box protects the terminal PCB and wiring connections
made to the terminal PCB. Use the three 3/4 in. conduit hubs to wire the remotely installed IR
LEL detector and connect wiring from an external device, typically an RKI controller. The top hub
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 hub can be used for wiring.
WARNING: If the top conduit hub 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 11 for complete wiring instructions.
Use the junction box’s two mounting slots 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.
Detector Junction Box
The detector junction box is intended to be installed remotely from the M2A junction box.
The IR LEL detector is factory installed in the bottom 3/4” NPT conduit hub. A terminal
strip is provided for wiring connections and the detector is factory wired to one side of
this terminal strip. The other side of the terminal strip is for user-supplied wiring to the
detector terminal strip located in the M2A junction box. This wiring should go through
the top 3/4” conduit hub. Three spacers installed on the back of the junction box controls
the distance of the junction box from a mounting surface.
Infrared LEL Detector
The infrared LEL detector is made up of a miniature infrared combustible gas LEL
detector housed and encapsulated in a pipe nipple. The pipe nipple has 3/4” NPT threads
on each end and a 1 1/4” hex that allows removal or installation of the detector with a
wrench. A porous flame arrestor that is coated with a hydrophobic film that repels liquids
is on one end of the detector and allows sample gas to enter the detector. Four color coded
leads, red, white, green, and black, extend from the other end of the detector. The leads
allow you to connect the detector to the terminal strip.
Calibration Adapter/Splash Guard
A calibration adapter/splash guard is installed on the IR LEL detector. A fitting at the
bottom of the calibration adapter/splash guard allows a length of tubing to be connected
for calibration and routed to a more easily accessible location (near the M2A junction box
is optimal for ease of calibration). The calibration adapter/splash guard also protects the
detector from splashing water or direct water spray.
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.