March 2006 -- The IRA-E420SW1 and IRA-E420SW2 operate by detecting the precise intensity of infrared. The infrared signal emitted by a fire has a peak wavelength of approximately 4.4um, compared to around 2um for other high temperature objects and 0.5mu m for sunlight.
An optional optical (4.3mu m bandpass) filter is available which promises a better than 80 percent transmittance of the peak wavelength for the IRA-E420SW2 and better than 70 percent for the IRA-E420SW1. Previous versions of the sensor achieved just 60 percent transmittance.
Directivity of the new devices has been improved to 50 degrees, a 25 percent improvement on earlier infrared sensors. The high sensitivity and excellent signal to noise ratio, gives these PIR sensors a significant performance advantage over thermistor or UV sensor-based fire detection systems.
Supply voltage is 3 to 15V and operating temperature is -25 to 70 deg C.
The devices measure just 9.2mm in diameter with a profile of 4.5mm.
Murata
