Siemens QRA4.U UV Flame Detector

The Siemens QRA4.U UV Flame Detector delivers reliable ultraviolet flame sensing for burner control and combustion safety, detecting UV radiation in the 190–270 nm range from gas and oil flames to verify ignition and trigger safe shutdown if flame is lost. It is intended for direct burner or boiler mounting using a ¾”-14 NPSM threaded connection and includes a ~1.8 m cable with a weight of about 0.18 kg, suited to compact industrial installations. Operating from -20°C to +60°C with an IP54-rated enclosure (installation dependent) and a maximum combustion chamber pressure of 150 mbar, the QRA4.U is compatible with Siemens burner controllers in the LFL, LME, LGB, and LMV series. Common applications include industrial boilers, gas burners, oil-fired systems, furnaces, thermal processing equipment, and power generation units where flame safety monitoring and ignition verification are essential.