STEMCO Capillary Switch

Thermostat Switches Monitor Hot Air Tunnel Dryers


Capillary Switch Controls, Snap Disc Limits

Capillary Switch Monitor Air Tunnel TemperatureIn a commercial or industrial hot air tunnel used for shrink wrap or for drying, a double bulb and capillary thermostat switch and a snap disc thermostat switch are commonly used.

Generally P/N 351-253890 double bulb and capillary thermostat is found in these systems, as well as P/N 351-254243 can be used in it’s place.


Thermostat Switches

Double Bulb and Capillary Switch

The double bulb thermostat switch activates the heating elements when the machine is turned on. When the temperature of the tunnel gets to maximum temperature the capillary switch shuts the heating elements down. Once the minimum temperature is hit the heating elements are turned on again and the cycle is started over.

The heating elements are wired through a second device on the capillary switch which is affixed to another bulb, and when the current draw is increased heat is created. If the second bulb senses that temperature, or the current draw is too high, the capillary switch will shut the heaters down. Parts can now be sent through the heated air tunnel by a conveyor at a controlled speed.


Snap Disc Thermostat Switches

A second limit, snap disc thermostat switch, is placed in the airstream that will sense a temperature beyond the first control switches. These switches are calibrated to the maximum temperature and will shut down the heating elements to prevent a critical event. This second temperature switch may be a manual reset requiring human intervention to re-start or automatic reset based on a pre-determined temperature.

To view our standard snap disc thermostat options, visit our website.

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