Rate-of-rise heat detectors operate on the assumption that the temperature at the ceiling of a standard room will increase faster from a fire than from normal atmospheric heating.
A rate-of-rise heat detector measures temperature changes in a room using a differential pressure switch. This switch contains an air chamber separated by a flexible membrane for ambient air.
When the temperature of the surrounding air changes, the air pressure increases, creating a differential pressure across the diaphragm.
The air chamber is designed with a calibrated leak so that normal temperature and pressure fluctuations in the chamber are evened out on both sides of the diaphragm and will not cause the alarm contacts to close.
During a fire, the temperature rises faster than usual, and the indoor side of the membrane rises. The leak cannot be compensated for and the diaphragm moves closing the detector contacts.
The rate-of-rise and fixed temperature heat detector combination is also manufactured and incorporates both technologies.
Learn more about Rate-of-rise heat detectors here : https://brainly.com/question/21053740
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