Bulletin 837 Temperature Controls are heavy-duty control circuit devices used in industrial applications where the temperature must be maintained within preset limits. These devices use a vapor pressure technology to sense changes in temperature. The pressure change is transmitted to the bellows through a bulb and capillary tube. Pressure in the system changes in proportion to the temperature of the bulb. Vapor pressure technology provides excellent repeat accuracy and exceptionally long life. Bulletin 837 Temperature Controls are designed for long life and heavy duty operation. Standard controls have precision snap-action silver contacts, and are offered in three different styles. All styles make use of bulbs and capillaries filled with a temperature-responsive liquid for detecting temperature changes. The controls are available in a wide variety of enclosures. There are many options and modifications available to meet most application requirements.