Siemens Flame sensor QRB1B-A035B40A

This photoelectric flame sensor (flame sensor / photodetector) is intended for diesel fuel and heavy oil burners. It is built into burner equipment and detects the light emission of a flame, sending an output signal to the burner control. It is designed for automatic combustion control systems in boilers, heat generators, and burner devices. The housing is made of heat-resistant plastic and the sensor is compatible with Siemens LOA and LMO controls.

Flame sensors for burner systems are selected by matching the original detection principle, spectral range, response time, cable length and connector type, and the required mounting sleeve. The sensor must be mounted so it has an unobstructed line of sight to the flame, and it must be wired to the burner control (flame safeguard), which uses its signal to confirm ignition and sustained combustion. When choosing a replacement of this class, confirm the flame detector in front of you has the same electrical and physical interface as the one being replaced.

Common failure modes for this type of sensor include a contaminated optical window, an aged sensing cell that outputs a weakened signal, or a broken sheath. If the sensor fails, the burner control may not detect a flame; after the safety time, the control initiates a lockout. The burner may fail to start or stop mid-operation even with a healthy flame, so check the optical window for dirt and the sensor alignment before replacing parts.