Siemens „QRB1A-A070B70A2“-Flammensensor

The Siemens QRB1A-A070B70A2 is a flame sensor used in burner systems to confirm that combustion has actually started. During the ignition sequence, the burner control opens the fuel valve and energises the ignition transformer; the sensor must detect the flame within the safety time, or the control goes to lockout. This component is part of the flame-sensing loop that directly reports to the burner control, and its output determines whether the system continues to run or shuts down for safety. Parts of this type are selected primarily by detection principle—ionisation, UV, or IR—depending on the fuel and burner class. For gas burners, ionisation is common; for oil and industrial burners, UV or IR detectors are used because the flame is luminous and the sensor must have a direct line of sight. Other selection parameters include spectral range, response time, cable length, connector type, and mounting sleeve size. When replacing a flame sensor of this type, check that the detection principle matches the existing burner control and that the physical mounting arrangement (thread, flange, or bayonet) is compatible. Typical failure modes include a contaminated optical window, a weakened sensor cell that produces a signal below the detection threshold, or a broken sheath that allows moisture ingress. Clean the lens with a lint-free cloth and solvent, but if the signal remains weak, replace the sensor. The catalogue lists this article under multiple manufacturer codes, which can be cross-referenced with the burner control documentation to verify interchangeability.