PT495 Series Detector
(Ultra1000)
Rev 5.11
36
Sensor Sensitivity
Sensor should always be calibrated in fresh air using recommended calibration
gas. When calibrated properly if the sensor reaction is slow then the sensor head
assembly should be replaced. Refer to Parts List for sensor head part number.
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 2 thumb screws on the transmitter
board face plate and pull the board slowly. Disconnect the ribbon cable and
to remove the transmitter board assembly.
4.
Disconnect the sensor wires from the terminal block on the connection
board.
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 4. Be sure
to follow the color code as labeled on the terminal and to ensure that 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.
