Wet Pipe Riser
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”.
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.