Larson Electronics, LLC
Phone: (877) 348-9680
Fax: (903) 498-3364
www.larsonelectronics.com
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EXP-TSTAT-125.250-60.250F-0.25-V1-15L
CALIBRATION
WARNING:
Hazard of Electric Shock. Extreme care
should be exercised during calibration adjustments
because of shock hazard due to exposed electrical
terminals. Failure to comply can result in electrical
shock or electrocution.
These controls are factory calibrated to the range indicated on
the control adjustment knob.
If calibration is required, either one of two methods may be
followed.
1.
2.
If accurate measurement standards are not available, the ther-
mostat can readily be adjusted to a known temperature standard
such as boiling water (212°). See Figure 13.
With the aid of an accurate thermometer or other temperature
measuring device, recalibration may be performed within the
process as in Figure 14.
For either method, the following general calibration procedures
should be followed.
Figure 13
CALIBRATION
DANGER:
Calibration will involve exposure of inter-
nal control terminals to ambient conditions during
some part of the recalibration procedure.
Combustible materials which cause hazardous
conditions must not be present during recalibra-
tion process — otherwise explosion may result.
1.
2.
Heat water bath or the equipment in which the control is
installed (tank, die, platen or machine) to the selected calibra-
tion temperature. The entire sensing bulb and at least one foot
of its capillary tube are to be exposed to calibrating tempera-
ture. With thermostat energized, allow process or bath to reach
setpoint. This is accomplished when thermostat begins cycling
action.
Compare adjustment knob cut off temperature indication
against actual temperature to which sensing bulb is exposed.
Figure 15 shows example of a control knob showing a control
indication of 250°F when true process temperature measured
230°F. In this example, the control knob must be rotated 20°
counterclockwise to bring the 230°F knob marking under the
index mark in order to recalibrate the control.
3.
Without disturbing the shaft setting, loosen the thermostat
knob set-screw and re-align dial setting accordingly. Retighten
knob set-screw.
4.
Recheck for thermostat operation as per steps 2 and 3 and make
further calibration adjustment if indicated.
5.
Recheck of thermostat operation following final adjustment
completes the calibration procedure.
IMPORTANT:
Under no circumstances must the temperature
range, and in particular, the maximum temperature setting of con-
trol be increased above maximum temperature indicated on control
nameplate. Such changes voids U.L. listing of the control.
Thermometer
Load (Tank, vat, die or platen)
Indicated Temp.
True Temp
250
200
A
Figure 14
Figure 15
