The Model VSR-S is a vane type waterflow switch for use on wet sprinkler systems that use 1" (25mm), 1¼" (32mm), 1½" (38mm) or 2" (50mm) pipe size. The unit may also be used as a sectional waterflow detector on large systems.

Unique Features

  • Works on commercial or residential systems
  • NEMA 4 weatherproof rating
  • Rated for 300 psi

Codes and Approvals

  • Complies with NFPA 13, 13D, 13R, 72

Engineering Specifications

Small Pipe Waterflow Alarm Vane Switches: UL Listed waterflow alarm switches shall be furnished and installed at each sprinkler system branch line connection to the wet pipe main where indicated on the drawings, and as required by NFPA Standards. Mounting shall be by means of a 1 inch TEE fitting installed in the branch line. Vanes shall be field installed on the switch from a selection supplied with the switch and fit pipe sizes 1 inch through 2 inches. Waterflow switches shall be capable of operation in system pressures up to 300 PSI, maximum surges of up to 18 FPS and alarm activation at 10 GPM. Switch configuration shall consist of two sets of single pole double throw (S.P.D.T.) Form C synchronized sets of contacts rated at 10A, 125 VAC and 2A, 30 VDC. Switch enclosure shall meet NEMA 4 rating and shall be equipped with an instantly recycling adjustable retard with a 0-90 second range. Enclosure cover shall be held captive by tamper resistant screws or supervised for removal by a cover tamper switch. Waterflow alarm vane switch shall be Model VSR-S manufactured by Potter Electric Signal Company.

Additional Information for Engineers:

  • This one device works on any 1" - 2" tee for commercial or residential installations indoors, outdoors or areas that get hosed down. There's no need to inventory multiple devices depending on the installation
  • The two switches are completely seperated to provide compliance with NEC regarding the separation of low and high voltage in an enclosure. There is no need for special wire or wire procedures

Installation Tips

  • Make sure the correct paddle is used for the TEE it will be installed in
  • The bull portion of the TEE must be factory 1" NPT. Reducing bushings and mechanical TEEs are not allowed
  • Make sure the VSR-S is screwed into the TEE to the proper depth, 1 11/16 from the top of the bull portion of the TEE to the base of the VSR-S

Tech Tips

  • The retard/switch assembly is field replaceable if necessary
  • Either switch can be connected to a fire panel or used to switch voltage to a local bell
  • Do not connect 120 vac directly to the switch. It does not require power. It is just a switch to activate a fire panel or switch voltage to turn on a bell, the same way a light switch is used to turn on a light

Additional Information

If there is a shut off valve in line with the VSR-S it should be monitored. Closing this valve can prevent an alarm.

Click here to view more information on the VSR-S, including its datasheet and other resources.

For additional questions, contact customer service:, or tech support:

Back to Latest News