Enclosure 6N Pressure Switches
Page 7
CHAPTER
4
TROUBLESHOOTING
In-service problems are unlikely, but the following paragraphs suggest ways to verify any
problems that might arise:
1.
Pressure Switch Leaks
If a leak is suspected, isolate the pressure switch from the rest of the system. Connect
the switch and a calibrated pressure gauge downstream from a pressure source and
shutoff valve. Apply normal system pressure, isolate the gauge and Pressure Switch
from the pressure source with the shutoff valve for at least one minute, and check for
leaks as evidenced by a drop in the gauge reading.
If a leak is verified, return the unit for repair. Contact ITT directly, or your local sales
representative or distributor (see
2.
Failure to Switch
If application of pressure or vacuum 10% greater than the adjusted setpoint fails to
produce actuation, first check for contamination in the process connection, and verify
that the expected pressure is reaching the sensing diaphragm or piston.
If the Belleville spring can be heard to audibly snap, but an ohmmeter indicates no
electrical switching, the cause is probably stuck or burned switch contacts, or the
switch element has moved away from the position where it was synchronized with
the snap action. Return the unit for repair.
If application of pressure or vacuum 10% greater than the adjusted setpoint fails to
produce an audible snap of the Belleville spring, there is probably a mechanical
failure or binding due to contamination. Return the unit for repair.
3.
Calibration Shifts
If it is suspected that the setpoints have shifted, recheck them per paragraphs 4 and 5
of Chapter 3. If you verify unstable or drifting setpoints, return the unit for repair.