RKI Instruments 65-2398RK - Manual (Page 7)

65-2398RK Combustible Gas Transmitter • 3
Infrared LEL Detector
The infrared LEL detector consists of the detector housing body, detector housing cap, cap
gasket, and the plug-in sensor.
Figure 2: Infrared LEL Detector Component Location
Detector Housing Body
The detector housing body protects the electronic components within the housing. Use the
mounting threads at the top of the housing to screw the IR LEL detector into the 3/4” NPT
hub on the bottom of the junction box. 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 amplifier.
The housing includes three sockets installed on a circuit board. These sockets accept the
plug-in sensor’s three pins to provide an electrical connection for the sensor. The circuit
board with the sockets conditions the sensor’s signal before the signal reaches the
amplifier.
Housing Cap & Cap Gasket
The housing cap screws onto the detector housing body. It retains the plug-in sensor and
protects it from damage. A foam gasket is installed inside the housing cap that seals
against the sensor face. A hydrophobic membrane on the outside of the cap face keeps
water and particulates away from the sensor face behind the cap. Unscrew the detector
cap to access the plug-in sensor for maintenance or replacement. A cap gasket seals the
interface between the housing body and cap.
Plug-In LEL Sensor
The plug-in sensor is secured in the detector assembly by the housing cap. The sensor pro-
duces a millivolt output that corresponds to the detection range of the transmitter.
Plug-In IR LEL Sensor
Detector Housing Cap
Cap Gasket
Hydrophobic
Membrane
Detector Housing Body