The Waterflow Indicator is a vane-type waterflow switch designed to detect a sustained flow of water exceeding 10 gpm. It is intended for use on wet-pipe sprinkler systems only. The Model VSR has a built-in adjustable pneumatic retard device delays actuation of the electrical switches to reduce the possibility of false alarms caused by one or more transient flow surges. The Model VSR-S does not have a retard to prevent false alarm, therefore, it should NOT be used on systems with variable water pressure, except in the case of elevator recall. The unit includes two single-pole double-throw snap action switches used to operate local alarms, indicate signals to annunciator panels, trip municipal fire alarm boxes, start fire pumps, or any other function that can be initiated or controlled by the opening or closing of an electrical switch. The device may be installed on the main riser to give a system waterflow signal or on branch feed mains, cross mains, or branch lines to give a waterflow signal by zone or area.