The model VSR-AT is an electronic vane type waterflow switch foruse on wet sprinkler systems. It is UL Listed and FM Approved foruse on steel pipe schedules 10 thru 40 sizes 2" thru 8". See orderingInformation chart.The VSR-AT may also be used as a sectional waterflow detector on largesystems. The VSR-AT has two sets of alarm contacts and an adjustableinstantly recycling electronic retard. The alarm contacts are actuatedwhen a flow of 10 GPM (38 LPM) or more occurs downstream of thedevice. The flow condition must exist for a period of time necessary toovercome the selected retard time.The VSR-AT may be remotely tested without flowing water by usingthe optional auto test Control model ATC-1or ATC-4 or the use ofaddressable relays and monitor modules as part of a listed addressable fire alarm panel.