601CH detectors are generally faster than ion-chamber and optical detectors in responding to fires that start by smoldering. They are also more tolerant of positioning and can be mounted in locations where there are likely to be obstacles to free smoke plume movement.

Heat detectors offer an acceptable, but less sensitive alternative to smoke detectors if environmental conditions rule out their use. 601H-R (rate-of-rise) and 601H-F (fixed temperature) detectors detect abnormally high rates of rise of temperature and abnormally high (static) temperatures respectively.

601P detectors are capable of detecting the visible smoke produced by materials which smoulder or burn slowly, i.e. soft furnishings, plastic foam etc; or "smoke" produced by overheated but unburnt PVC.

601PH 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.

The 601F point type flame detectors form part of the 600 series of conventional detectors. Both the 601F and the 601FEx are full featured solar blind flame detectors for indoor use and boast a high degree of false alarm immunity.