Specifications

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 shut down or startup of equipment, such as computers
or other second alarm devices. The flow of water into the
sprinkler system piping effectively converts the dry system
into a wet pipe system. In the event that the fire subsequent-
ly produces sufficient heat to operate a sprinkler head, water
will flow from that sprinkler, controlling or suppressing the
fire.
Dry Pilot Single Interlock Preaction Systems are used
in areas that may be subjected to freezing conditions. They
can also be utilized to obtain installed sprinkler heights and
pipe lengths greater than the allowed for wet pilot systems.
A dry pilot line installation consists of an air-pressurized line
of closed sprinklers or pilot line detectors (Reliable’s Mod-
el F1-FTR), which are located in the area to be protected.
NFPA 72 or the Authority Having Jurisdiction (AHJ) should
be consulted for spacing and elevation requirements for the
installation of dry pilot sprinklers/detectors.
In the system’s trim, the dry pilot line is connected to a
Model LP Dry Pilot Line Actuator. This actuator functions
very much like a miniature dry pipe valve. It requires only 8
to 28 psi (0,6 to 1,9 bar) of air pressure (depending on the
water supply pressure) to maintain the Model DDX Deluge
Valve in a closed position. In areas where moisture-laden air
could cause a freezing condition, or other problems in the
dry pilot line, the use of a dry, compressed gas such as nitro-
gen is suggested. Approved gas handling regulators (see
Reliable Bulletin 254) and connections are recommended.
When one of the dry pilot line sprinklers/ detectors actuates,
the air pressure in the line is reduced, thus opening the Mod-
el LP Dry Pilot Line Actuator, which in turn releases the DDX
Deluge Valve and fills the fire sprinkler piping with water.
However, water does not flow from the fire sprinkler system
until one of its sprinklers fuses from the heat of the fire.
The fire sprinkler system piping may be required to be su-
pervised (see NFPA 13) with air pressure. Loss of this super-
visory air due to a damaged sprinkler or the sprinkler piping
will not cause the Model DDX Deluge Valve to open. This is
accomplished by the ½” check valve which is located in the
valve’s trim. The check valve prevents air pressure (from the
dry pilot line) from escaping out of the Model LP Dry Pilot Line
Actuator. A low air pressure switch (System Sensor EPS40-2
or EPSA40-2) is also provided in the trim. The contacts of
this switch will close on the loss of air in the sprinkler piping,
thereby providing a low air alarm to aid in insuring the in-
tegrity of the sprinkler system piping. The pressure switch’s
low air alarm should be wired to a supervisory alarm bell or
the building’s alarm system (Note: The wiring for closing of
contacts on the loss of pressure is made on the “COM” and
“B” terminals of switch 2.)
Damage to a dry pilot line sprinkler/detector or the dry pi-
lot line piping that causes a significant loss of pressure will
cause the Model DDX Deluge Valve to open, flowing water
into the fire sprinkler system piping. The supervisory air sup-
ply for both the dry pilot line and the fire sprinkler piping can
effectively be maintained by means of pressure-switch-op-
erated, tank-mounted air compressor and a Reliable Model
A-2 Pressure Maintenance Device (see Reliable Bulletins
254). The compressor’s tank provides a reserve supply of
air, whereas the Model A-2 Pressure Maintenance Device
consistently regulates the air pressure of both the dry pilot
line and the fire sprinkler piping.
The dry pilot line sprinklers/detectors must be more sen-
sitive to the heat from a fire than the sprinklers in the fire
sprinkler system. The Model F1-FTR (Fixed Temperature Re-
lease) is specifically designed for use in dry pilot line oper-
ated sprinkler systems. Dry pilot line sprinklers are detection
devices and do not provide any water to aid in the firefight-
ing capability of the fire sprinkler system.
To fully operate a dry pilot line preaction system, the heat
from a fire must fuse a dry pilot line sprinkler/detector thereby
releasing the air pressure from the Model LP Dry Pilot Line
Actuator. The water pressure is then able to overcome the
pressure differential of the actuator, allowing water to flow
from the Model DDX Deluge Valve’s push rod chamber. As
this water pressure is lost in the push rod chamber, the sup-
ply pressure will then force the valve’s clapper open, flowing
water into the fire sprinkler system piping. Water flowing into
the system will flow through the intermediate chamber of the
deluge valve to a mechanical sprinkler alarm (optional) and/
or will simultaneously produce water pressure that causes
the transfer of contacts in the (optional) alarm pressure
switch mounted in the trim. If provided, the alarm pressure
switch can electrically initiate the shut-down or start up of
equipment, such as computer, HVAC, or other secondary
alarm devices (Note: the wiring contacts for the alarm pres-
sure switch are the “Common” and “A” contacts). The flow
of water into the sprinkler system piping converts the dry
system into a wet system. In the event that the fire subse-
quently produces enough heat to operate a fire sprinkler
head, water will flow from that sprinkler, controlling or sup-
pressing the fire.
Listings & Approvals:
(Only when used with Reliable’s Trim Sets.)
1. Reliable’s 2” (50 mm), 2½” (65 mm), 76 mm, 3” (80 mm),
4” (100 mm), 165 mm, 6” (150 mm) and 8” (200 mm) Elec-
tric Actuation Single Interlock Preaction Systems, Wet Pilot
Line Single Interlock Preaction Systems and Dry Pilot Line
Single Interlock Preaction Systems are Underwriters Labo-
ratories, Inc. Listed and UL certified for Canada (cULus)
in the Special System Water Control Valve-Deluge Type
(VLFT) category.
2. Reliable’s 2” (50 mm), 2½” (65 mm), 76 mm, 3” (80 mm), 4”
(100 mm), 165 mm, 6” (150 mm) and 8” (200 mm) Electric
Actuation Single Interlock Preaction Systems are certified
by Factory Mutual Approvals (FM). Factory Mutual does
not approve the use of smoke detectors or cross zoned de-
tectors in preaction systems.
3.