46-624 Series 3 Liquid Level Switches ASME B31.1 Construction
13
4.2
What To Do — Every 12 Months (minimum)
4.2.1 Switch Corrosion Inspection
For every 12 months in service, conduct the following
maintenance and inspection checks in addition to cus-
tomer specific or code requirements.
NOTE: Conduct this inspection every 3 months for applications
where the switches are exposed to corrosive environments.
1. Disconnect power to the switch.
2. Remove switch housing cover to inspect switch mecha-
nisms for visible signs of corrosion on terminals and wires.
NOTE: When removing switch housing cover, secure housing base to
prevent rotation of the base and enclosing tube. If cover
proves difficult to remove, loosen housing base set screws
before using a crossbar to free the cover. Loosening the set
screws will prevent accidental rotation of the enclosing tube
and possible leakage of process media.
3. Dry contact switches should be inspected for excessive
wear on actuating lever or misalignment of adjustment
screw at point of contact between screw and lever. Such
wear can cause false switch actuating levels. Adjust switch
mechanism to compensate (if possible) or replace switch.
4. Controls may sometimes be exposed to excessive heat or
moisture. Under such conditions, insulation on electrical
wiring may become brittle, eventually breaking or peeling
away. The resulting bare wires can cause short circuits.
Check wiring carefully and replace at the first sign of
brittle insulation.
5. Vibration may sometimes cause terminal screws to loosen.
Check all terminal connections to be certain that screws
are tight. Refer to
Figure 15
.
6. Conduct a continuity test for switch contacts, using a low
voltage DC circuit with an indicator.
7. Switches that are corroded or that failed the contact conti-
nuity test should be replaced. DO NOT operate your
control with defective or maladjusted switch mechanisms
(refer to bulletin on switch mechanisms furnished for
service instructions.)
8. Verify that switch housing cover and conduit seal are
properly closed after each inspection of the switch
mechanism(s).
NOTE: In applications with presence of salt-laden air or corrosive
vapors, contact MAGNETROL for possible alternate switch
mechanisms.
Mechanism
clamping screw
Terminal screws
Figure 15
