Siemens Flame sensor QRB1A-A068B70B

This Siemens QRB1A-A068B70B flame sensor (photodetector) is for oil burners and operates on a photoelectric principle. It monitors flame presence in combustion processes using diesel or heavy oil, and is intended for boilers, heat generators, and burner devices. The sensor is mounted in the burner assembly and is compatible with Siemens LOA and LMO series controls. Its housing is made of heat-resistant plastic, and it is suited for automatic combustion control systems. The device provides a fast response to flame loss and accurate flame monitoring.

When replacing a flame sensor of this type, confirm the detection principle, spectral range, response time, cable length and connector type, and mounting sleeve arrangement to match the existing installation. The sensor must have a direct line of sight to the flame, so verify that the mounting position is unobstructed. Before ordering, compare the cable length with the existing harness and ensure the mounting sleeve fits the burner.

Typical failures include a contaminated viewing window, an aged sensing cell that produces a weakened signal, or a broken cable or sheath. When the sensor cannot confirm flame within the safety time, the burner control goes to lockout. Check the viewing window for dirt, the sensing element for degradation, and the cable for continuity.