Instruction manual

2.
General Description
Single Interlock Preaction Systems are designed for wa-
ter-sensitive areas that require protection from inadvertent
water flow into the sprinkler system piping.
Sprinkler piping in single interlock systems can effectively
be supervised by means of a Reliable Model B Air Compres-
sor Panel or Model C Pressure Maintenance Device. Loss
of 2 psi (0,14 bar) supervising pneumatic pressure, due to
a damaged sprinkler or sprinkler pipe will not cause water
to flow through the Model DDX Deluge Valve and into the
system piping. A significant loss of pneumatic pressure
will activate a trouble-annunciating device when the system
pressure falls below 0.7 psi (0,05 bar).
When one electrical detector senses the presence of fire,
the electrical releasing control panel activates fire alarm de-
vices and latches the normally-closed solenoid valve (175
psi (12,1 bar) or 250 psi (17,2 bar) Rated) in the open posi-
tion (Note: Arranging detectors in a cross-zoned pattern will
require operation of two detectors before the solenoid valve
can open). The solenoid valve, when closed, retains suf-
ficient water pressure in the pushrod chamber of the Model
DDX Deluge Valve to maintain it closed. Energizing the so-
lenoid valve relieves the water pressure, thus opening the
Deluge Valve and allowing water to flow into the sprinkler
system.
To fully operate a cross-zoned single interlock system, two
electrical detectors must activate and a sprinkler head must
open. During the early stages of a fire, smoke or heat ac-
tivates the first detector, which causes the control panel to
produce a local alarm and an alarm at the main fire alarm
panel. Electrical relays inside the releasing control panel
can be used to shut down air moving equipment or activate
security doors and other electrical devices when the panel
goes into the first alarm condition. Subsequent activation of
a second, nearby or adjacent, detector will cause the panel
to energize the solenoid valve open and release water into
the sprinkler system piping. Water flowing into the sprinkler
system piping will simultaneously produce water pressure
that causes the transfer of contacts in the pressure switch
mounted in the Reliable Single Interlock Preaction System’s
riser assembly. This pressure switch can electrically initiate
the shutdown or startup of equipment, such as computers or
other second alarm devices. The flow of water into the sprin-
kler system piping effectively converts the dry system into a
wet pipe system. In the event that the fire subsequently pro-
duces sufficient heat to operate a sprinkler head, water will
flow from that sprinkler, controlling or suppressing the fire.
The major benefits of a single interlock preaction system,
when compared with a wet pipe (deluge) system are as fol-
lows:
A fire alarm sounds prior to the operation of a
sprinkler head, which may enable extinguishing
the fire by handheld means before the actual op-
eration of any sprinklers and subsequent water
damage.
A trouble annunciator signals whenever the in-
tegrity of the piping or sprinklers is accidentally
or intentionally disturbed; however, no water flow
or water damage will occur at that time.
Speedy detection and an early fire alarm are pro-
vided by fire detectors, without the delay associ-
ated with water delivery time in the event of a fire.
Note that with a wet pipe system, the fire alarm is
delayed until after water has begun flowing from
an operated sprinkler head.
At the heart of Reliable’s Single Interlock Preaction Sys-
tem is the Model DDX Deluge Valve. This Deluge Valve is a
hydraulically operated, straight-through-design, differential-
type valve (see Fig. 1). System maintenance is simplified
since priming water is not required and the Deluge Valve
can be reset externally without cover removal. This is ac-
complished by pushing in and turning the external reset
knob at the rear of the Deluge Valve (see Fig. 1). This feature
provides a significant system-restoration time advantage.
The Reliable Single Interlock Preaction System trim set
(see Fig. 2) provides all of the necessary equipment for con-
nections to the Model DDX Deluge Valve’s pushrod cham-
ber inlet and outlet ports, the 1¼” main drain, alarm devices,
air supply, water supply, and required pressure gauges.
This trim set is available in individual parts, in time-saving,
segmentally assembled kit forms, or fully assembled to the
Model DDX Deluge Valve (with or without a control valve).
Listings & Approvals
Reliable 2” (50mm), 2
1
/
2
” (65mm), 3” (80mm) and 76mm
Single Interlock Preaction Systems are Underwriters Labora-
tories, Inc. Listed and UL certified for Canada (cULus) in the
Special System Water Control Valves – Deluge Type (VLFT)
category.
Reliable 2” (50mm), 2
1
/
2
” (65mm), 3” (80mm) and 76mm
Single Interlock Preaction Systems are certified by Factory
Mutual Approvals (FM). Factory Mutual does not approve
the use of smoke detectors or cross-zoned detectors in pre-
action systems.
The NYC acceptance number for this system is MEA 258-
93-E.
Reliable Single Interlock Preaction Systems are UL Listed
and FM Approved only when used with the trim components
shown in Fig. 2.
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