Siemens Flame sensor QRB1A-A070B70A2

Siemens flame sensor QRB1A-A070B70A2 is a burner component that verifies combustion during ignition. It belongs to the flame sensor category and is identified by type designation 4031.090. This sensor is designed for Master air heater control models 4031.090 for BV80, BV100, BV160, and BV280. During start-up, it must detect the flame within the safety time, otherwise the burner control goes to lockout.

When selecting a flame sensor of this kind, confirm the detection principle matches the burner control: ionisation for gas burners, UV or IR for luminous oil or industrial flames. Check the mounting arrangement (thread, flange, or bayonet), cable length, connector type, and mounting sleeve size. Compare these parameters against the existing installation before ordering.

Typical failure modes include a contaminated optical window, a weakened sensor cell producing a signal below threshold, and a broken sheath that lets moisture in. On the equipment, this appears as no flame confirmation within the safety time, causing burner lockout. Clean the lens first; if the signal remains weak, replace the sensor.