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44-604 Top Mounting Liquid Level Switches
5.1.2 Check complete unit
1. Reconnect power supply and carefully actuate switch
mechanism manually (using a non-conductive tool) to
determine whether controlled equipment will operate.
Caution:
With electrical power on, care should be taken to avoid
contact with switch leads and connections at terminal
block.
2. If controlled equipment responds to manual actuation test,
trouble may be located in the level sensing portion of the
control–float(s), stem(s), and magnetic attraction sleeve(s).
NOTE: Ensure that liquid is entering the storage tank or vessel.
A valve may be closed or a pipe line plugged.
Caution:
Be certain to pull disconnect switch or otherwise ensure
that electrical circuit(s) through control is deactivated.
Close operating medium supply valve on controls
equipped with pneumatic switch mechanisms.
3. With liquid in tank or vessel, raise the liquid level above
the set points. Magnets should “pull-in” on rising level. On
Model T21 the lower float actuates the upper switch, and
the upper float actuates the lower switch. If magnets fail to
“pull-in”, lower the level and purge pressure.
a. Disconnect wiring from supply side of switch mecha-
nism(s) and remove electrical conduit or operating
medium line connections to switch housing.
b. Remove switch housing assembly by loosening hex nut,
which is located immediately below housing base.
4. With switch housing assembly removed, inspect attraction
sleeve(s) and inside of enclosing tube for excessive corro-
sion or solids buildup, which could restrict movement,
preventing sleeve(s) from reaching field of switch
magnet(s).
5. If differential has been changed in the field by reposition-
ing the lower jam nuts on the float stem, check tightness
and position of the jam nuts. Refer to Figure 6.
NOTE: Differential adjustment affects a change in the amount of level
travel between switch-on and switch-off actuation. Do not
attempt adjustment without first consulting factory for assis-
tance in computing level differential change for your control.