The Model VSR is a vane type waterflow switch for use on wet sprinkler systems. It is UL Listed and FM Approved for use on steel pipe; schedules 10 through 40, sizes 2" thru 8" (50 mm thru 200 mm), and schedule 5, sizes 2" thru 6". LPC approved sizes are 2" thru 8" (50 mm thru 200 mm).

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.

Unique Features

  • The industries only non-corrosive insert in the saddle prevents water from coming in contact with any metal thus eliminating any possibility of corrosion
  • Field replaceable 0-90 second retard assembly with easy to read contrasting timing indications
  • Easy to read terminal strip identification to make wiring easier
  • Visual Switch Activation
  • 450 PSI rating
  • Solid metal enclosure with factory installed weatherproof gasket standard

Codes and Approvals

  • Complies with all applicable service use requirements of: NFPA 13, 13D, 13R, 72
  • UL, CUL & CSFM Listed, FM Approved

Engineering Specifications

UL, CUL Listed / FM, LPCB, VdS Approved and CE Marked vane type waterflow switches shall be furnished and installed at each sprinkler system connection to the wet pipe main where indicated on the drawings and plans and as required by applicable local and national codes and standards. The device shall consist of a saddle with factory installed non-corrosive insert, gasket and non-corrosive vane and trip stem assembly as well as a field replaceable adjustable time delay / switch mechanism to prevent false alarms from water surges. All wetted parts of the waterflow switch shall be non-metallic to resist being affected by or contributing to corrosion. The waterflow switch enclosures shall be NEMA 4 rated and the cover shall be held captive by tamper resistant screws. It shall be possible to install an optional cover tamper switch to detect removal of the enclosure. The field replaceable instantly recycling adjustable pneumatic retard shall provide a 0-90 second time delay and visual indication of activation. Expiration of the retard time shall result in the simultaneous operation of two sets of single pole double throw (SPDT) switch contacts rated at 10A, 125VAC and 2A, 30VDC. Each switch contact shall have a separate wiring chamber and separate conduit entrance to comply with the NEC requirements for separation of power limited and non power limited conductors without the need for special wire or wire methods. The device shall be listed for pressures up to 450 psi, maximum water surges of 18 fps and alarm activation by a continuous flow of 10gpm. The device shall be Listed for installation on pipe schedules from 5-40 for 2” – 6” and schedule 10-40 for 2” through 8” size. The waterflow switch shall be a model VSR manufactured by Potter Electric Signal Company LLC.

Additional information for Engineers

  • It is the only flowswitch with no metal to water contact. It cannot contribute to or be affected by corrosion. 
  • Physical barriers on switches allow easier compliance with NEC requirements for separation of voltages

Installation Tips

  • On horizontal pipe install on the top half of the pipe only. This prevents any debris in the pipe from possibly obstructing the paddle movement
  • Do not trim the paddle
  • Make sure the non-corrosive insert fits inside the hole in the pipe & tighten the U bolt evenly

Tech Tips

  • Wiring the VSR to operate a bell is the same as wiring a light switch to turn on a light. Run Neutral wire from the source directly to the neutral on ther bell. Run the hot wire to the COM terminal. Run the switched wire from the N.O. terminal to the black wire on the bell.
  • The retard can be field replaced without draining the system or removing the flowswitch

Additional Information

Click here to view more info about the VSR Series Flowswitch

For additional questions, contact customer service: sales@pottersignal.com, or tech support: tech@pottersignal.com


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