Technical data

2.1.2 Model DDX
The Reliable Model DDX Deluge Valve is a hydraulically-operated, differential-type, latching valve with
external reset designed for use as a main system control valve in deluge, preaction and low pressure
dry fire protection systems. The Model DDX Deluge Valve can be trimmed to create several types of
systems by utilizing manual, hydraulic, pneumatic, or electrical actuation devices or combinations of
these devices. Using a Model DDX Deluge Valve as the main system control valve allows the end-user
flexibility in changing the system type by reconfiguring the trim if the need arises; a new Model DDX
Deluge Valve does not need to be purchased.
In the set position, the Model DDX Deluge Valve clapper is physically held closed by the lever and
pushrod assembly (Figure A). In this position, supply pressure acts on the underside of the clapper
and also on the push rod through the push rod chamber inlet. The resultant force on the push rod
is multiplied by the mechanical advantage of the lever and holds the clapper closed against normal
supply pressure surges. The push rod chamber supply valve remains in the open position when the
valve is in the set condition; any surge or increase in water supply pressure acting on the underside of
the clapper is equally transmitted to the push rod chamber to guard against accidental opening of the
deluge valve
24.
The Reliable Model DDX Deluge Valve may be operated by any listed or approved releasing device
which opens sufficiently to vent the push rod chamber. When a releasing device activates, the push
rod chamber vents to atmosphere through the chamber outlet. Since the pressure cannot be replen-
ished through the inlet restriction as quickly as it is vented, the push rod chamber pressure falls rapidly.
When the push rod chamber pressure approaches approximately one-third of the supply pressure,
the upward force of the supply pressure acting beneath the clapper overcomes the reduced push-rod
force allowing the clapper to open. When in a flowing condition, the clapper is pushed and held open
by the flow of water to the system (Figure B).
Figure A:
DDX VALVE SET POSITION