2.
Measure the resistance. If the resistance is more than 1.0 ohm, remove the switch from service.
3.
Connect the meter to the NC and COM contacts.
4.
Cause a low-pressure fault condition using one of methods below:
NOTICE
Do not simulate fault conditions while the burner is firing.
• Turn the pressure switch set point counter-clockwise until the switch trips.
• De-pressurize the volume of gas the low-pressure gas switch is sensing.
• For FRI/6 regulators, open the side tap on the opposite side of the FRI/6 regulator.
• For DMV and MBC safety shutoff valves, open the port 1 pressure tap.
5.
When the fault occurs, measure the resistance. If the resistance is more than 1.0 ohm, remove switch
from service.
6.
Allow the burner to go through a startup sequence, and then verify that the burner faults and is not
allowed to light.
7.
When testing is complete, close all pressure test points used.
8.
Open the upstream ball valve SLOWLY to allow gas pressure to gradually re-enter the system.
NOTICE
Opening the upstream ball valve too fast can permanently damage the pressure switch.
High-pressure gas switch
Perform these tasks to check the resistance of the high-pressure switch both in normal operation and in a
fault state.
NOTE
A resistance of more than 1.0 ohm indicates that the switch contacts are starting to either corrode or
carbonize.
Service and maintenance
Global Finishing Solutions
34
239-062 rev 5
