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Part II - Adjustments
5/16" open end wrench (2 required for 822e only)
afTer coMpleTIng adjusTMenTs on all 120 serIes
TeMperaTure conTrols, be sure To re-InsTall adjusTMenT
cover. do noT over TIghTen cover screws.
NOTE: for set point adjustments and recalibration, connect control to a
calibrated temperature source and stabilize unit.
Types C120, F120
NOTE: adjust set point by holding plunger with 3/16" open end wrench and
turning the calibrating screw with another 3/16" open end wrench (see
figure 5). Turn clockwise (left) to increase or counter-clockwise (right) to
decrease setting.
Adjustment Procedure
for C120/F120
Figure 5
Types B121 and E121
adjust set point by turning external knob and pointer to desired setting on
scale (see figure 6).
Types B122 and E122
Individual switches may be set together or apart up to 100% of range.
when not set together, the front (low) switch cannot be set higher than the
rear (high) switch. Turning external knobs will increase or decrease each
switch setting independently (see figure 6).
Type E122P
Individual switches may be set together or apart by up to 60% of range.
The front switch is set by turning the internal calibrating screw to the
right for lower set point and turning to the left for higher set point. when
not set together, the front switch must be set higher than the rear switch.
Turning the external knob will increase or decrease each switch setting
simultaneously without disturbing their relationship (see figure 6).
Figure 6
TOOLS NEEDED
3/16" open end wrench (2)
1/4" open end wrench
5/64" allen wrench
external knob and
pointer adjustment
IMT120-10
Indicating Temperature Switch Types 820E & 822E
NOTE: prior to making any controller adjustments, the cover and adjustment
knob should be removed. when adjustments are completed, all applicable
parts should be replaced.
Type 820E
Move the set point adjustment pointer up scale beyond the brown Indicating
pointer. This permits checking the set point by moving the lever arm upward
with a finger or tool simulating thermal assembly movement. connect test lights
to indicate switch operation or listen for the switch to click. loosen adjustment
"a" and move the adjustment pointer until it agrees with the Indicating pointer.
when the switch clicks re-tighten the screw.
NOTE: Type 822e has a single knob and pointer for both switches. both
switches are standardly, factory set together within 5% of the dial range.
Turning the knob positions both switches simultaneously, maintaining a
constant separation between them.
Type 822E
remove the explosion-proof die-cast cover to permit access to the switches.
Move the adjustment pointer up scale beyond the Indicating pointer by an
amount greater than the difference between the switch settings by moving
the actuating lever upward with a finger or a tool simulating thermal assembly
movement. connect test lights to indicate switch operation or listen for the
individual switch clicks.
The set point of switch #1 is determined by the red adjustment pointer. The
set point of switch #2 may be adjusted by up to 25% of the range span
below the switch #1 set point by turning adjustment "d" in (clockwise).
see back page for 822e dual switch adjustment. The set point of switch #2
should not be above that of switch #1.
To align switch #1 to the adjustment pointer, loosen adjustment "a" and set
the adjustment pointer to the scale, then re-tighten adjustment "a".
NOTE: Indicating pointer deflection (820e, 822e): The indicating pointers
will read slightly low when the bulb temperature is 15° above the controller
setting. This deflection is normal and repeatable (approximately 0.5% of
scale range on single switch models) and is due to the transference of the
switching mechanism load to the thermal system. It can be measured by
moving the setting pointer from the high to the low end of the scale and
observing the resultant indicating pointer deflection.
NOTE: Indicating pointer adjustment (820e, 822e): use an accurate test
thermometer such as a thermocouple with its probe mounted directly to the
center of the sensing bulb. before making any adjustments, allow process
temperature to stabilize; i.e., successive on-off cycles repeated.
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