All flame detectors have between 90° and up to 120° cone of vision. One can assume that the wider the cone of vision, the more area the detector can cover. However, this is both misleading and in many cases totally incorrect.

In the case of the IR3 detector, which has a 100° cone of vision but can see a 1 foot 2 inch (0.3m2) fire at a distance of 215 feet (65m), the area the detector can cover is far greater (four times) than that of a detector with a 120° cone of vision which can only see the same size fire at 50 feet (15m).

Most flame detectors are placed in the corner of a structure so as to get maximum coverage along both walls and into the area. In this scenario, the additional 30° is meaningless as it is outside the walls of the building.

When deciding installation locations, Protectowire offers a Laser Detection Area Coverage Pointer that can assist by defining the 90° cone of vision on site.