The Series 65 Optical Smoke Detector uses light-sensing technology to detect a fire. The external detector moulding has an indicator LED which is white in the quiescent state but produces red light in alarm.
- Wide-operating voltage of 9–33 V DC
- Wide-operating and storage temperature of -20°C to +60°C
- Can be used on security systems
- Electrically and mechanically compatible with Series 60
- Proven detection performance
- Responds well to slow-burning, smouldering fires
- Well-suited to bedrooms and escape routes
- Unaffected by wind or atmospheric pressure
- Flashing LED and magnet operated test switch option
The Series 65 Optical Smoke Detector has a moulded self-extinguishing white polycarbonate case with wind resistant smoke inlets. Nickel plated stainless steel wiper contacts connect the detector to the base. Inside the case a printed circuit board has the optical system mounted on one side and the signal processing electronics on the other. The sensing chamber is a black moulding configured as a labyrinth which prevents penetration of ambient light. The labyrinth has a fine gauze insect-resistant cover. The chamber houses an infrared light emitting diode (LED) and a photo-diode which has an integral visible-light filter as extra protection against ambient light.
When smoke enters the chamber, a fraction of the collimated light is scattered onto the photo-diode. If the resulting signal from the photo-diode is above a preset threshold, the LED emits two more bursts of light, this time at two-second intervals. If light is scattered onto the photo-diode by both these pulses – due to the presence of smoke – the detector signals an alarm state by switching the alarm latch on, increasing the current drawn from the supply from about 40μA to a maximum of 75mA. This fall in the impedance of the detector is recognised by the control panel as an alarm signal.