Coffee Break Training: Fire Alarms & Detection: Rate Compensated Heat Detectors   [open pdf - 168KB]

"A rate-of-rise device is a common type of heat detector that responds when there is a rapid temperature increase in the space where it is located. In some cases, however, a spot-type rate-of-rise detector may not be suitable for the environment that needs to be protected. A rate compensated detector may offer an appropriate alternative. A rate compensated detector operates when the ambient air temperature reaches a predetermined level, regardless of the rate at which it increases. The detector will operate at its design temperature during slow-building fire conditions or will respond promptly during rapid fire buildup. A rate compensated detector relies on the physical property that metals expand when heated. Rate compensated detectors have typical temperature ratings between 135 °F and 220 °F (57 °C and 104 °C). These are spot-type detectors that have a sealed, external metallic tubular casing. Inside, there is a pair of electrical contacts that are attached to the sealed end of the tube. The alloys of the external tube and internal struts are different materials that heat and expand at different rates. Designed to resist thermal energy absorption and sealed inside the outer tube, the struts respond to temperature changes more slowly."

Report Number:
Coffee Break Training - Fire Protection Series No. FP-2012-29REV
Public Domain
Retrieved From:
United States Fire Administration: http://www.usfa.fema.gov/
Media Type:
Help with citations