Ultra-High-Temp Thermal Switches

Product Announcement from Control Products, Inc.

Ultra-High-Temp Thermal Switches-Image

These switches, with their longer probes, are highly resistant to shock and vibration, while still maintaining exceptionally close repeatability. Since the entire probe is heat sensitive, it acts as an averaging device, thus compensating for temperature gradients. These switches function as temperature controllers, safety cutoffs for equipment protection, and as indicators of overheat conditions.


· All welded stainless construction

· Glass hermetically sealed connectors where applicable

· Specific probe materials can be selected for maximum sensitivity

· Inconel X springs insure high temperature repeatability

· Platinum iridium contacts provide excellent arc erosion protection and constant contact resistance

· Special glass insulators or mica are used for thermal and electrical isolation

Factory calibrated. Depending on switch type, CPI Rod and Tube thermal switches are factory calibrated at any temperature within the range of 0° to 1850°F. They can operate in probe ambient temperatures from -65°F to 2000°F, and show excellent resistance to momentary overshoots. Drift free performance is assured throughout their long life.

Immune to problem environments. Sealed for protection against the effects of moisture, sand and dirt, these Rod and Tube thermal switches are also designed to withstand severe shock and vibration with no shift in calibration. They meet or exceed the requirements of MIL Std 810.

Torque free mounting. Over-torquing during installation will not affect calibration because the mounting threads are isolated from the temperature-sensitive probe.

Special Fine Adjustable Feature. CPI high temperature Rod & Tube switches (X-1, X-2, X-3) can be ordered with a mechanism that permits fine adjustment in the field. The simplified design eliminates the need for special tools to adjust temperature setting. Calibration can be re-set within a range of 250°F (plus or minus) of original factory setting.


CPI utilizes the differential expansion of two metals to operate the switching mechanism in our Rod and Tube thermal switches (a quartz rod is used in the X-3).

The high expanding tube pulls the low expanding rod down in the switch, allowing the hook action spring to make contact with the calibration spring and complete the electrical circuit. (Schematic shown is close on rising temperature). The hook in the spring allows for maximum undershoot temperatures required by the Military. Thermal calibration of the switches is readily accomplished by adjusting the contact spring position with the calibration screw which is then sealed and locked in place. Both the rod material and the tube material can be varied for sensitivity or differing response times in the desired temperature range.


CPI Rod and Tube thermal switches are used in harsh applications such as jet engines, gas turbines, ram air temperature systems, after-burners, railroad switch N BALL deicers, diesel stack over-heat sensors, extruders, flame detectors and electronic heating and cooling systems.