PT395 Series LEL Sensor Rev 6
29
Sensor Replacement
Before opening the sensor junction box and replacing the sensor, de-classify the area
and follow the instructions below.
1.
Verify that there are no hazardous levels of combustible gas in the air.
2.
It is recommended that power to the sensor should be turned off to avoid any
short circuit to the power supply. However, it is not necessary to turn off the
power in order to replace the sensor head.
3.
Remove the junction box cover. Unscrew the 2 thumb screws and pull the
transmitter board slowly. Disconnect the ribbon cable and to remove the
transmitter board assembly.
4.
The sensor head assembly is connected via 3 wires on the bottom terminal
labeled “SENSOR”. Disconnect the wires.
5.
Unscrew the stainless steel sensor head to remove from the junction box.
6.
Install the new sensor head. Lubricant can be used to coat the threads of the
sensor head.
Do not use the silicone based lubricant
7.
Connect the sensor head wires to the terminals as shown in figure 3. Be sure the
wires are secure and not loose.
8.
Plug in the ribbon cable to the transmitter board and secure the board with
thumb screws. Do not over tight the screws.
9.
Power up the sensor, if disconnected , and let the sensor warm-up as indicated in
the “Start up” section in this manual.
10.
Calibrate the sensor. Follow the instructions in calibration procedure in this
manual.
