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Installation of a Water Flow Switch

The Water Flow Switch is mounted on a wet-pipe system only. The water flow in the pipe deflects the paddle. The deflection of the paddle produces a switched output. All detectors will activate on a continuous flow of water greater than 10 gallons per minute (gpm) but will not in subtle surges of less than 4 gpm.

Information from Potter Electric Water Flow Alarm Switch Installation Guide:

“The units should not be installed within 6″ (15cm) of a fitting which changes the direction of the water flow or within 24″ (60 cm) of a valve or drain.”

The Water Flow Switch should be mounted 6 to 7 feet above the floor to minimize the switch from being damaged.

Below are two pictures of a Wet Pipe Sprinkler Riser, One was installed properly and the other is “WRONG”.

Wet Pipe Sprinkler Riser

Incorrect Installation

Wet Pipe Sprinkler Riser

Correct Installation

I’ve been in the fire protection business for many years and when I see something like this it makes me mad. I cannot believe that a fire protection contractor can let this happen, then the AHJ approved it. I hope by showing the correct and incorrect ways of installation of fire protection equipment will help us all.

2 Responses to Installation of a Water Flow Switch

  • sprink says:

    Although this article is about the proper installation of a flow switch, I’d like to point out that there may be an issue with the installation of the water pressure switch that is installed on the top of the retarding chamber of the alarm valve in the lower photo. normally the retarding chamber is vented through the water motor gong, and piping. This installation has the pressure switch on top of the chamber with no venting. you need a tee and a resticted vent on top of the retarding chamber to allow it to drain, and prevent false alarms.

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