Some flame detectors, for example, a UV tube, may have a nonfailsafe failure mode, meaning their operation needs to be verifiedperiodically. Continuous operation can be achieved by using a device containinga mechanical shutter that allows the detector to self check by simulation of ano flame condition.More modern flame detectors use more sophisticated methods forself checking. A characteristic of nearly all flames is that they flicker. Thisis a product of the fuel type, combustion process and mechanical design of theburner. Flicker frequency tends to increase with firing rate as a result ofhigher air velocity and fuel mixing at the burner head or nozzle. Flickerfrequency varies along the flame path dropping off significantly towards theend of the flame. This characteristic can be used to tune a flame detector todiscriminate one flame from another in multi-burner systems or to discriminatethe flame from other background radiation. These more intelligent flamedetectors monitor the flicker and the self check using software rather thanmechanical operation.
Siemens UV Flame detectors Models
Siemens QRA2 UV Flame Detector
Siemens QRA73.A17 110v Self Checking Flame Detector
Siemens QRA53.E17 110V Self Checking UV Cell
Siemens QRA73.A27 230v Self Checking Flame Detector
Siemens QRA55.E27 230v Self Checking UV Cell
Siemens QRA53.G17 Flame Detector
Siemens QRA53.E27 230v Self Checking UV Cell
Siemens AGG16.C Adaptor For Mounting QRA53
Siemens QRB1A A148B70B Photocell