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Temperature Switch
with Terminal Block
General Instructions
The SOR® nuclear temperature switch utilizes a SAMA Class II thermal system.
NOTE: This type of system requires that the entire length of the
sensing bulb be exposed to the temperature being measured.
In considering the validity of a measurement, remember that
temperature-sensing devices respond only to the temperature that they
experience. It may be considerably different from the temperature one is
attempting to measure if the sensor is of improper size or configuration,
or if the sensor is not adequately coupled thermally to the media whose
temperature is being measured. The calibration procedures given
below will assure accurate and repeatable measurement of the set points of
SOR temperature switches. If the switch is normally mounted in a thermowell,
consideration should be given to the effect this may have on the accuracy of
the switch. It is recommended that a heat transfer paste or oil be used to thermally
couple the sensing bulb to the thermowell, both in service and during testing.
NOTE: If you suspect that a product is defective, contact the factory or the SOR
Representative in your area for a return authorization number (RMA). This product
should only be installed by trained and competent personnel.
Recommended temperature measurement procedure for switches used to sense
temperatures of liquids and steam with set points below 200°F:
1.
Use a liquid bath (ethylene glycol, water, oil, etc.) with sufficient circulation to provide a
uniform bath temperature and efficient transfer of heat from the liquid to the sensing bulb.
2 . Fully submerge the sensing bulb into the bath. Direct-mount sensing bulbs should be
submerged up to the bottom of the process connection threads.
3. Locate the tip of the temperature measuring standard (thermocouple, RTD, etc.) at the
mid point of, and adjacent to the sensing bulb.
4. Locate the sensing bulb and temperature measuring standard so that they do not touch
the sides or bottom of the bath or the heating and cooling coils.
5. When the bath temperature is within 3°F of the set points, it is recommended that the
temperature of the bath be changed at a rate of 0.1°F per 5 seconds or slower.
6. The minimum and maximum bath temperatures that the switch sees during testing
should be duplicated each time the switch is tested. It is recommended that the
temperature of the bath be changed from the normal operating temperature to the
critical set point and back to the reset. Do not overshoot the critical set point if the
switch is going to be cycled more than once during the test.
Design and specifications are subject to change without notice.
For latest revision, go to sorinc.com
Form 1473 (05.13) ©SOR Inc.
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Recommended temperature measurement procedures for switches used to sense
temperatures of liquids and steam with set points above 200°F:
Recommended procedures for set points above 200°F are identical to those for set
points below 200°F with the exception of the bath used to test the switches. We
recommend either a circulated oil bath or a fluidized sand bath. The bath should be
tested for uniformity of temperature from top to bottom and side to side. If necessary,
steps may be taken to improve the uniformity of temperature, such as altering the air
flow through a sand bath or improving circulation or stirring.
Recommended temperature measurement procedures for switches used to sense air
or gas temperature:
Switches used to measure the temperature of air or gas should be tested in such a way that
it simulates the actual service conditions as closely as possible. Chances of measurement
error are much greater in air because of its poor thermal conductivity. Rate of change of
temperature, velocity of air flow, location of sensing bulb, and location of standard must
be duplicated as closely as possible for successive calibration checks to assure repeatable
results. If the switch is being used as a room thermostat, the entire switch should be
placed in a test oven for calibration and testing. If only the sensing bulb is exposed to the
air or gas being measured, then only the sensing bulb should be inserted into the oven or
test apparatus for calibration and testing. In this case the switch housing should be kept at
room temperature.
NOTE: For switches that monitor HELB (High Energy Line Break), use “Recommended Temperature Measurement Procedure for Switches Used to Sense Temperature of Liquids and Steam” for
the most accurate results.
RT Housing
3/4 NPT(F)
Direct Mount
1/8 NPT(F)
Vent Connection
Cover Screws
Body
Process Connection
Conduit Connection
Mounting Holes
2/4
Sensing Bulb
Form 1473 (05.13) ©SOR Inc.
Mounting Hardware Fasteners per SOR Test Report 9058-102 consist of two 1/4-20,
Grade 5 screws (not supplied). Torque screws to 70 to 85 in-lbs.
Maintenance Replace cover gasket (SOR P/N 8923-181) whenever cover is removed or
minimum of once every 5 years, whichever comes first. Remove the four cover screws.
Remove old gasket. Place new gasket between housing and cover. Line up holes in cover,
gasket and housing. Insert the 4 screws and torque each to 7 to 10 in-lbs.
Installation
Refer to applicable drawing for mounting dimensions of specific model number. The
vent connection must be plugged or vented to dry atmosphere as required by application
requirements.
Direct Mount
Line mount or mount to a rigid mounting surface with process connection down (6
o’clock). If the switch must be removed from a thermowell, loosen the process connection
by placing a 1-1/4” wrench on the hex adjacent to the process threads. Do not use wrench
on the sensing body. (See drawings.)
Site Storage
Store switch in a dry area in the original shipping package. Shelf life is 10 years for a
maximum ambient temperature of 80°F, based on aging data in SOR Test Report 9058-102.
Electrical Connection
Conduit should be
installed without
applying strain to the
housing. Screw terminal
block is provided with
marked insulation as
denoted below. Tighten
screw terminals to
10 in-lbs. (1.1 N-M)
SPDT DPDT
Temperature Temperature
Form 1473 (05.13) ©SOR Inc.
3/4
Drawing 9013747
Calibration
To adjust temperature at which switch
will operate, remove cover and tighten
the hex head adjusting nut with a 3/4inch wrench to increase temperature;
loosen to reduce temperature.
Switching Element
Sighting across the top of the 3/4-inch
hex adjusting nut to the scale gives
approximate set point temperature.
Use accurate test gear external to the
temperature switch to set or check set
points. See recommended measurement
procedure on Pages 1 & 2. After
calibration is complete, reinstall the cover
with new gaskets or o-rings as required
by the maintenance instructions.
The switching element has been positioned with a dial indicator to a
tolerance of +/-.002 inches. Do not move this switching element! It’s position
has nothing to do with the set point adjustment. Any movement can either
render the switch inoperative or cause the switching element to be damaged
with over-temperature.
Adjusting Nut
Calibration Scale
Printed in USA sorinc.com
14685 West 105th Street, Lenexa, KS 66215 913-888-2630 800-676-6794 USA Fax 913-888-0767
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Form 1473 (05.13) ©SOR Inc.
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