Potter Releasing Systems - Manual (Page 16)

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Basic Sprinkler Systems and Water Flow Alarm Devices
Wet Pipe Sprinkler Systems
There are three basic types of wet systems
#1. Straight Pipe Riser:
This type of system does not have an alarm valve. There is either a riser check valve or backflow preventer
which isolates the sprinkler water from the supply water. The main riser is fed directly from the water supply
and branches out throughout the protected premises. These systems must use a vane (paddle) type flow switch.
Due to constant fluctuations in water pressure, the waterflow switch should have a time delay or retard to
prevent false alarms. The retard time is used to overcome water surges.
As the main riser extends upward, there may be branch lines going out to various floors or other areas of the
protected structure. Depending on local or national requirements, there may be a water control valve and
waterflow switch on the branch line. The valve would allow that branch to be shut down for maintenance or
other reasons while leaving the rest of the system functional. The purpose of the waterflow switch would be to
add another zone to the system to better locate the open sprinkler.
Note: All water control valves shall be supervised per NFPA13 2010 8.16.1.1.2.1.