SERIES 65 heat detector A1R

The SERIES 65 heat detector is a conventional detector composed of a self-extinguishing, white polycarbonate housing. Nickel plated stainless steel wiper contacts connect the detector to the base. Inside the case a printed circuit board holds the signal processing electronics.

The SERIES 65 heat detectors are ideal for environments that are dirty or smoky under normal circumstances and can be used for applications where smoke detectors are unsuitable.

In the A1R, BR and CR variants a pair of NTC thermistors are mounted on the printed circuit board in such a way that one thermistor is exposed to give good thermal contact with the surrounding air while the other thermistor is thermally insulated.

Under stable conditions both thermistors are in thermal equilibrium and have the same value of resistance. If air temperature increases rapidly the resistance of the exposed thermistor becomes less than that of the insulated thermistor. The ratio of the resistance of the thermistors is monitored electronically and an alarm is initiated if the ration exceeds a factory pre-set level. This feature determines the 'rate of rise' response of the detector.

The SERIES 65 heat detectors switch to the alarm condition in the event of an inadmissible rise in air temperature and in the event of exceeding a fixed alarm threshold of 65°C for the A1R detector, 85°C for the BR detector and 100°C for the CR detector.

The SERIES 65 heat detector CS uses a single NTC thermistor, which provides a voltage proportional to the surrounding air temperature. This detector only switches to alarm status when a fixed alarm threshold of 100°C is exceeded.