Socialize with us:

Capillary Thermostats

Capillary and bulb style thermostats use expansive liquid to open or close contacts in response to changes in temperature. No matter which style or model you choose, all capillary thermostats work with the same physics. A fluid is encapsulated in a metal tube (bulb and capillary) and when the temperature changes, the fluid expands or contracts. This fluid change moves the head, which triggers a snap-action switch, either opening or closing the circuit.

The bulb is typically a larger diameter tube mounted in the material stream being sampled. The capillary is a small tube that carries the liquid away from the bulb towards the head. The head can be a diaphragm or bellow, which moves with changes in temperature.