The Siemens QRA4.U is a UV phototube flame detector for supervising gas flames and yellow- or blue-burning oil flames, and for ignition spark proving, sensitive to ultraviolet radiation in the 190-270nm range so it stays unaffected by glowing refractory or daylight. Housed in an aluminium body with a 3/4"-14 NPSM mounting thread and 1.8m connecting wires, it fits directly onto the burner or boiler front for intermittent-operation flame supervision. Rated IP54 with a nominal UV cell life of about 10,000 hours at 50°C, it is built by Siemens for use with a wide range of Siemens burner controls including the LFL, LFE and LMV series, alongside compatible flame safeguard units such as the Siemens LFS1.11A2.
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