What is rate-of-rise detector and how does it work?

RATE-OF-RISE: A temperature increase at the sensor of 15F (9C) or more per minute activates the rate-of-rise feature. This closes the contacts in the sensor to transmit the alarm condition to the fire alarm control panel. When the rate-of-rise element alone has been activated, the sensor is self-restoring.

How does a rate-of-rise heat detector work?

Rate-of-Rise Heat Detector Rate-of-rise heat detectors sense the heat in the room. The detectors register 70 degrees as a baseline; when the heat in the room rises rapidly above 70 degrees, the alarm is activated. This type of sensor is triggered by the “rate of change” rather than the temperature itself.

What is rate compensated heat detector?

Description. The Rate Compensated Heat Detectors provide accurate, positive response to fire threats. They are typically used to activate alarms and actuate extinguishing systems. They virtually eliminate false alarms. They combine the best features of both Fixed Temperature and Rate-of-Rise detectors.

At what temperature should a heat detector be activated?

135 degrees F
Heat Detectors react to the change in temperature caused by fire. Once the temperature rises above 135 degrees F (57 C) or 194 degrees F (90 C), the heat detector will send a signal to an alarm panel and trigger an alarm.

When to use a rate of rise detector?

The rate-of-rise detector, however, will function when the rate of temperature increase exceeds a predetermined value, typically around (7 to 8°C) per minute. Rate-of-rise detectors are designed to compensate for the normal changes in ambient temperature (less than [6.7°C] per minute) that are expected under nonfire conditions.

When does a rate of rise heat alarm go off?

Heat detectors have two main classifications of operation, “rate-of-rise” and “fixed temperature”. Rate of Rise Thermal Detectors triggers the fire alarm when the rate of temperature increase in the surroundings rises above a certain rate.

What happens when a rate of rise sensor is activated?

When the rate-of-rise element alone has been activated, the sensor is self-restoring. FIXED TEMPERATURE:If the temperature of the center disk rises to the sensor’s rated temperature, the fixed temperature element activates. This closes contacts in the sensor and trans- mits an alarm condition to the fire alarm control panel.

How are fixed temperature and rate of rise heat detectors designed?

Combination fixed-temperature/rate-of-rise detectors contain more than one element that responds to a fire. These detectors may be designed to respond from either element or from the combined partial or complete response of both elements.