Sprinkler Water Flow Flapper

Have you ever wondered what the inside of a sprinkler waterflow device looked like?  Well there are a few different types of waterflow devices as far as looks but they all basically work the same.  They mount to the outside of the fire alarm sprinkler riser with U bolts but it is whats inside that does the magic.  As you are probably aware, automatic sprinkler systems have water constantly sitting in the pipes.  This is why it is commonly referred to as a "Wet System".  On the back side of the sprinkler waterflow is a flapper that fills the area of the sprinkler riser.  If a sprinkler head happens to burst in the event of a fire, the water will have a place to escape the system.  However when this is accomplished, the water in the system must be replaced.  As water is sent back into the system it flows past the flapper behind the sprinkler waterflow device and moves it up like a light switch.

The flapper switch has a retard device on it to slow down the activation time.  This is required as a switch that is too sensitive may be activated with a simple city water surge.  The back flow preventor or OS and Y (outside screw and yoke) is in place to reduce the back flow of water from the system thus resulting in fewer false alarms.  With the retard on the water flow and OS and Y the "wet system" type fire sprinkler setup is pretty full proof.