Mini Temperature Switch

The mini temperature switch protects equipment with a simple mechanical trip: a sealed bulb and capillary filled with a liquid whose vapour pressure rises with temperature act on a diaphragm, which operates a snap-action microswitch at the set point. No power is needed for sensing, and the switch keeps working during a power loss, which is why mechanical temperature switches remain the norm for safety shutdowns on pumps, compressors, engines and heaters.

The mini version is built for tight spaces on skids and machinery. Five ranges between −15 and +250 °C are available, with the set point adjustable across the selected range and repeatability better than 1 % of span. The output is one SPDT microswitch rated up to 5 A at 250 VAC. The sensing bulb is 316 stainless steel, mounted directly through a ½" or ¾" thread, in a thermowell, or remotely at the end of a capillary of up to 10 m, so the switch body can sit away from heat and vibration. Pressure capability is that of the thermowell and process connection.

Accessories are capillary, compression fittings, a terminal box, mounting brackets, and helical or surface bulbs for air and surface measurement.

Applications are safety-temperature monitoring, alarms and shutdowns in chemical, power, water and wastewater and mining plants. For hazardous areas or higher contact ratings, see the compact temperature switch.