Not all Bulbs, Probes and Capillary Tubes use a fluid fill, some use a gas. There are a large number of different fluids and gases used. This is based on:
- What material is being sensed for temperature
- Temperature range of the switch
- Other external requirements to the switch
There are also other engineering and design requirements that are taken into account when a fill material is chosen. A large number of capillary tubes use a variation of an alcohol fill. Some even have odors added so a leak can be detected.
No matter which style or model you choose, all of the capillary thermostat switches operate using the same physics. A fluid or gas is encapsulated in a metal and when the temperature changes it either expands or contracts. This change moves a diaphragm which is in touch with a snap action switch and either opens or closes a circuit.
STEMCO Capillary Switches
Our capillary style thermostat switches are high limit switches. A limiting device is installed in a piece of equipment with an adjustable or fixed temperature setting, 0-700°F, that when the temperature is met either opens or closes a circuit. These temperature switches are available as an automatic or manual reset. Capillary thermostats are typically installed as a back-up or secondary control to prevent the equipment from exceeding a specified temperature, high or low.
For more information about STEMCO capillary switches, click here to contact us.