Flame Detector

What the flame detector does

The flame detector tells the program controller that a flame is genuinely there. Depending on the burner it is an ionisation probe, an ultraviolet cell or an infrared flicker detector, and a high-temperature variant of the same device is used where the detector has to sit in a hot furnace environment instead of in the burner air box. The detector and the supervision logic that reads it have to be matched to the controller.

Most flame failure lockouts are not detector failures. Dirty or misaligned optics, an ignition cable leaking high voltage into the probe circuit, poor earthing, wrong electrode position and an inadequate pre-purge are all more common causes and all cheaper to fix. Before replacing a detector it is worth checking the sighting position, the lens, the cable routing and the earth connection; a detector that has genuinely aged out tends to fail intermittently rather than cleanly.

• Types in service: ionisation probe, ultraviolet cell, infrared flicker detector, with high-temperature variants for hot furnace mounting.
• Send the detector code and the program controller type together — the two have to be matched as a pair.