Siemens Flame sensor QRB1C-A050B40A

Photoelectric flame sensor for use with oil (diesel and heavy-oil) burners. It detects flame presence and sends a signal to the burner control unit; if the flame is lost it initiates a rapid shutdown of the fuel supply. The model has a compact design for easy installation and is specified for fast response to flame loss. The catalogue article number is 884.211.021. It is designed to fit Siemens burner controls.

When selecting a replacement sensor of this type, compare the detection principle (UV or IR), spectral response, required response time, cable length and connector type, and the mounting sleeve that fits the burner head. Position the sensor so it has a clear view of the flame core and is not exposed to excessive heat. Before ordering, verify that the burner control is compatible with the output characteristics of the sensor; if the cable length or connector differs, an adapter or a sensor with the same electrical interface is needed.

When a sensor of this class fails, the burner control often locks out and shuts the fuel valves, because no flame signal is received within the safety time. Typical causes are a contaminated or fogged optical window that reduces sensitivity, an aged detection cell that gives a weak signal even with flame present, or a broken or shorted cable. Check the optical window and signal path when diagnosing.