8
46-635 External Cage Displacer Actuated Liquid Level Switches
3.1.2 Inspect switch mechanisms, terminals, and
connections monthly
1. Switches should be inspected for excessive wear on actuat-
ing lever or misalignment of adjustment screw at point of
contact between screw and lever. Such wear can cause false
switch actuating levels. See switch mechanism bulletin
supplied with control should switch adjustment or replace-
ment be necessary.
2. DO NOT operate your control with defective or mal-
adjusted switch mechanisms (refer to bulletin on switch
mechanisms furnished for service instructions.)
3. Level controls may sometimes be exposed to excessive heat
or moisture. Under such conditions, insulation on electrical
wiring may become brittle, eventually breaking or pealing
away. The resulting “bare” wires can cause short circuits.
Check wiring carefully and replace at the first sign of brittle
insulation.
4. Vibration may sometimes cause terminal screws to work
loose. Check all terminal connections to be certain that
screws are tight.
5. On units with pneumatic switches, air (or gas) lines sub-
jected to vibration, may eventually crack or become loose
at connections causing leakage. Check lines and connec-
tions carefully and repair or replace, if necessary.
NOTE: As a matter of good practice, spare switches should be kept
on hand at all times.
3.1.3 Inspect entire unit periodically
Isolate control from vessel. Raise and lower liquid level to
check for switch contact and reset.
3.2 What to avoid
1. Never leave switch housing cover off the control longer
than necessary to make routine inspections.
2. Never place a jumper wire across terminals to “cut-out”
the control. If a “jumper” is necessary for test purposes, be
certain it is removed before placing control into service.
3. Never attempt to make adjustments or replace switches
without reading instructions carefully. Certain adjustments
provided for in level controls should not be attempted in
the field. When in doubt, consult the factory or your local
representative.
4. Never use lubricants on pivots of switch mechanisms.
A sufficient amount of lubricant has been applied at the
factory to ensure a lifetime of service. Further oiling is
unnecessary and will only tend to attract dust and dirt
which can interfere with mechanism operation.
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