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Does anyone have or know where I can get some information on a rate of rise algorithm for a heat detector i.e. how does it determine when 8 degrees C per minute rate of rise has been exceeded. Also, where can I get some information on what the temperature does in a real fire e.g. if the temperature jumps by 15 degrees and then doesn't increase any further, can this happen in practice and would a rate of rise heat detector give an alarm for this.

Thanks in advance.

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Rate of rise detectors have a chamber in them that is filled with air. The chamber has a small h*** in it that "breathes" as the temperature changes. Since air expands when it gets warmer, the air leaves the chamber as it is heated (ie. influenced by fire). The design is such that if the temperature increases more then the prescribed rate (generally 6 celcius per minute if I recall correctly), the h*** in the chamber cannot equalize the difference in pressure quickly enough, and pushes a set of contacts together, providing a short on the circuit, and setting the panel into alarm.

Rate of rise detectors also have a fusible element as well that fuses when a certain temperature is reached (Most of the time 57C/135F)

Hope this helps

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