A deluge system is used primarily in freezers or computer rooms
and is a fail safe method of using a wet system to protect an area.
The deluge system has a special valve which holds the water from
entering the system mechanically. All other aspects of the system
are like a wet system, it is calculated as one, and performs as
a wet system. The piping in the same as a pre-action system extends
to sprinklers which are closed and ready to fuse. The system piping
can be under air pressure which it called supervisory air or it
may not be. Since the valve must be tripped by sensors in the area
of protection, it is normally done with a separate set of electrical
These detectors send and signal back to the pre-action valve which
trips the valve. This case would be a single action pre-action valve.
Upon one signal the valve would release water into the system. In
the case where a greater measure of assurance against water inadvertently
entering the system, a double action system is used. In this case
the valve must have both a signal from the detectors in the area,
and the release of air in the system piping to release water into
Main Points to Establish
* Is the main control valve open and all valves down stream of the
connection to the water supply open?
* Is this and all other valves controlling water to the system locked
in the open position or supervised and functioning?
* Supply water pressure beneath the valve should be shown.
* Pressure in the auxiliary chamber on the side of the valve.
* If there is supervisory air, there should be air pressure indicated
in the system piping. This usually is a very low pressure.
* The alarms for a pre-action system are the same as for a wet accept
all pre-action valves use a panel which monitors the detection sensors
and supervisory air. Panel receives the signals and actually trips
* This valve allows the system to be drained and is used to test
to see if the city water valve is open. This is done by opening
the valve wide open while reviewing the pressure drop on the pressure
gauge. The loss should not be significant. If it is the city water
supply should be investigated.
Fire Department Connection
* This is used to allow the fire department to pump into, using
their pumper truck to supplement the city water pressure. Threads
should be checked to see if they meet standard threads used by local
Alarm Testing Apparatus
* Since the testing of a pre-action valve involves flowing water
into an area of high concern, this testing must be done by a qualified
contractor and special testing apparatus.
* There should be a supply of extra sprinklers in the facility as
per NFPA #13 and a sprinkler wrench.
* As you walk through a facility there should be no gaps in coverage
in those areas requiring sprinklers.
* The question should be asked if any area has been changed from
one occupancy to another after original system had been installed.
* Are any sprinklers blocked or painted?
* What is the age of the sprinklers?
Certification of Inspection
* The owner, under NFPA #13A, is responsible for certain tests and
the collection of certain data to demonstrate the performance capability
of the system. The owner should have documentation of periodic testing