Conventional Smoke & Heat Detection

Series 60 Ionisation Smoke Detector

The sensing part of the detector consists of two chambers - an open, outer ,chamber and a semi-sealed reference chamber within.

Mounted in the reference chamber is a Iow activity radioactive foil of Americium 241 which enables current to flow between the inner and outer chambers when the detector is powered up.

As smoke enters the detector, it causes a reduction of the current flow in the outer chamber and hence an increase in the voltage measured at the junction between the two chambers. The voltage increase is monitored by the electronic circuitry which triggers the detector into the alarm state at a preset threshold. An externally visible LED will light up when the detector changes to alarm state.
Heat Detectors Detector Bases

Series 60 Optical Smoke Detector

Optical smoke detectors incorporate a pulsing LED located in a labyrinth

within the housing of the detector. The labyrinth is designed to exclude light from any external source. At an angle to the LED is a photo-diode which normally does not register the column of light emitted by the LED.

In the event of smoke from a fire entering the labyrinth the light pulse from the LED will be scattered and hence registered by the photo-diode. If the photodiode "sees" smoke on the two following pulses, the detector changes to the alarm state when the indicator LED will light up. The detector housing is identical to that of the ionisation smoke detector. It is distinguished from this type by having an indicator LED which is clear in quiescent state but produces red light in alarm.

The optical detectors are easy to disassemble and clean without the necessity of returning them to the factory.

We supply and install conventional or addressable Smoke and Heat Detection to BS 5839 Pt1 2002. LPCB Control Panels up to 32 Zone. Addressable form 1 to 8 Loops ( Control Panels )