Skip to content

Waterflow Alarm Switch

UL Listed, Vane-type Waterflow Alarm Switch mount to water-filled pipes in fire suppression systems. Waterflow Alarm Switch in the pipe deflects a vane, which produces a switched output usually after a specified delay. Most of the Waterflow Alarm Switches have a pneumatically controlled mechanical delay mechanism.

Waterflow Alarm Switch usually installed in the main pipe or branch pipe of the sprinkler pipe system. When the vane detects the water flow, the water flow signal will be converted to electrical signal, and then switch on the alarm system or start the fire pump directly, at the same time, the fire zone will be indicated.

Waterflow Alarm Switch Feature

● Adjustable delay function

Adjust with rotating switch, accurate adjustable time within 0~90 seconds, high reliability.

● Air delay device with miniature bearing

Time consistency and reliability are assured

● Adjustable spring design

Convenient sensitivity adjustment, easy maintenance.

● Double micro switch design

One end can be used to operate the central control room, and the other end can be used to connect the alarm apparatus.

● Surface treatment

Red epoxy coating, high corrosion resistance performance

Specification of Waterflow Alarm Switch

Size2”/DN50 ~ 8”/DN250
Working PressurePN25/363PSI
Flow Sensitivity Range15-37.5L/MIN
Temperature Range0-68℃
Contact Rating

125/250VAC 5A

24/30VDC 3A

Waterflow Alarm Switch Assembly Diagram

Installation Guidelines

  • The water flow indicator can be mounted on horizontal or vertical pipe. On horizontal pipe it should be on the top of the pipe or the side of the pipe, do not at the bottom of the pipe on vertical.
  • pipe it should be mounted on the pipe which the water flow is upward.
  • The pipe length before and after the water flow indicator must be no less than 5 times the pipe diameter, and choose the correct water flow indicator according to the pipe nominal diameter.
  • technical parameter table. The water flow direction must be same as the arrow direction, must not be installed in opposite direction.
  • Leave enough space for easy installation and maintenance.
  • When drilling the hole with a hole saw, make certain that the center of the cut does not remain in the pipe.


  • Use vane-type waterflow detectors in wet-pipe systems only. Do NOT use them in dry pipe, deluge, or preaction systems. The sudden inrush of water in such systems may break the vane or damage the mechanism.
  • Do not use in potentially explosive atmospheres. Do not allow unused wires to remain exposed.

Field Wiring Diagam