Siemens Flame sensor QRB4B-C036B40B

The Siemens QRB4B-C036B40B is a flame sensor (photodetector) designed for monitoring flame presence in liquid fuel burners. It operates on the photoelectric principle, detecting light emission from the flame and transmitting a signal to the burner control. The sensor is made of heat-resistant plastic and features a compact design for easy installation. It is intended for use with diesel fuel and heavy oil, and is compatible with Siemens LOA and LMO burner controls. The device is manufactured in Germany and is integrated into the burner, aimed at the combustion zone.

When selecting a replacement flame sensor of this type, ensure the detection principle (UV or IR) matches the burner control's input requirements. The sensor must be compatible with the mounting sleeve design on the burner and the cable length and connector type must fit the existing setup. Verify that the sensor's spectral range and response time are suitable for the application. Always check the physical mounting arrangement and confirm compatibility with the burner control before ordering.

Common failure modes for this kind of sensor include contamination or soot on the sensor window, which can weaken the signal and cause intermittent lockouts. A damaged cable or cracked sheath can also lead to signal loss. An aged sensor cell may produce a weakened signal, resulting in the burner control entering lockout and closing fuel valves. Check the sensor window for dirt, inspect the cable for damage, and ensure the sight path to the flame is unobstructed.