601PH-M detectors react to the complete range of fire products, from slow smoldering fires, producing visible particles to open flaming fires producing large numbers of very hot smaller sized aerosols. 

The combination of optical and heat technology allows detection of clear burning fire products which hitherto could only be easily detected by ion-chamber detectors.

For normal ambient conditions the HPO behaves as a normal detector. Only when a rapid rise in temperature is detected does the sensitivity of the detector increase and the presence of smoke will confirm a fire condition which will be transmitted as an alarm level.

The 601PH-M design incorporates a unique "mousehole" optical chamber with an unrivaled signal to noise ratio providing high resilience to dust and dirt which means reduced servicing costs.

In addition a unique chamber cover actually draws slow moving smoke into the chamber to provide a more responsive detector.