Sealed Bimetal Snap Disc Thermostats
2570 Series Sealed Thermostat Switch
A large US based military vehicle company contacted us about a version of our thermostat that they could use in a harsh environment, high temperature application. They needed the device to be very rugged and robust but based on common commercial products with a long experience of performance in the field and quick availability.
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For more information about our epoxy sealed thermostats, contact our direct technical support at 715-831-6353.
The application was to improve the cold start ability of their approx 500hp diesel engine. They needed the thermostat to trigger a cold start process when the engine oil temperature was near or below freezing. The key requirement was to have the snap disc thermostat mount in a 1/2 NPT thread hole that they already had on their equipment.

Credit to Garett Mizunaka
We didn’t have any bimetal thermostats that met their description on our shelf, but were able to quickly adapt a unit for this application. The unit below was machined and tested in a few weeks to get them test samples. This included using their specified high temperature cables. (200ºC 16AWG)
These devices were calibrated to insure the temperature performance in the new housing was consistent. The large contact surface with the engine allowed the limit style snap switch to match the temperatures very closely. These ‘limit’ style switches turned the system on at or below 32 degrees and turned the cold start system off once the temperature increased to 42 degrees F.
Our temperature switches work by using a bimetal disc. The bimetal disc in the switch reacts to heat, and opens or closes a set of contacts based on what the ambient temperature is. This is works because the different metals in the disc react to heat in different ways, which causes the disc to bend.