Photo-electric smoke detectors incorporate a pulsing LED located in a chamber within the housing of the detector. The chamber 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 chamber, the light pulse from the LED will be scattered and hence registered by the photo-diode. If the photo-diode “sees” smoke on the two following pulses, the detector changes into the alarm state and the indicator LED lights up. IP rating = IP23D
ADVANTAGES
• Features: Flashing LED; Alarm indication: Clear LED, Red in alarm; Supply voltage: 9 to 33V
• Average stand-by current at 24V: 45uA; Average stand-by current at 9V: 40uA
• Alarm current at 24V: 52mA; Alarm current at 9V: 17mA
• Ambient temperature: 32 to 100°F; Max wind continuous: not affected
• Remote output (R-) characteristics: Current sink to -ve line, limited to 17mA. Note: when using a remote indicator a current-limiting series resistor may be required.