The Model VSR is a vane type waterflow switch for use on wet sprinkler systems. It is UL Listed for use on a steel pipe; schedules 5 through 40, sizes 2? – 6? and is UL Listed and FM Approved for use on steel pipe; schedules 10 through 40, sizes 2? thru 8? (50 mm thru 200 mm). LPC approved sizes are 2? thru 8? (50 mm thru 200 mm). See Ordering Information chart. The VSR may also be used as a sectional waterflow detector on large systems. The VSR contains two single pole, double throw, snap action switches and an adjustable, instantly recycling pneumatic retard. The switches are actuated when a flow of 10 GPM (38 LPM) or more occurs downstream of the device. The flow condition must exist for a period of time necessary to overcome the selected retard period.