Heat detector

Heat Detector

A Heat detector is a type of fire alarm system component designed to respond when the convected thermal energy of a fire increases the temperature of a heat sensitive element. The thermal mass and conductivity of the element regulate the rate flow of heat into the element. All heat detectors have this thermal lag. Heat detectors have a low false alarm rate but are slow to respond to fast-growing fires. Heat detectors are not meant to replace smoke detectors. They are often placed in kitchens and attics where smoke detectors are prone to false alarms.

Types of Heat Detectors

There are two main types of heat detectors: rate-of-rise (ROR) heat detectors and fixed temperature heat detectors.

Rate-of-Rise Heat Detectors

Rate-of-Rise (ROR) heat detectors are designed to respond when the temperature increases rapidly within a short period of time. These detectors measure the rate at which the ambient temperature is increasing. The alarm is triggered when the rate of temperature increase exceeds a predetermined value.

Fixed Temperature Heat Detectors

Fixed temperature heat detectors are designed to respond when the ambient temperature reaches a predetermined value. These detectors are activated when the temperature reaches a specific threshold, typically set at 135-140 degrees Fahrenheit.

Applications

Heat detectors are commonly used in environments where smoke detectors may cause false alarms, such as in kitchens, garages, and attics. They are also used in environments that are naturally dusty or dirty, where smoke detectors may not function properly.

Limitations

While heat detectors are less likely to cause false alarms compared to smoke detectors, they are also slower to respond to fires. They are not suitable for areas where rapid fire detection is required.

See Also

• Fire alarm system
• Smoke detector
• Fire safety