•
Low air pressure switch to indicate loss of air pressure
in system piping. Pressure switch shall be [cULus List-
ed][ FM Approved] and of the bellows activated type
enclosed in a weatherproof NEMA 4/4X rated enclosure
incorporating tamper proof screws. There shall be two
sets of SPDT (form C) contacts rated 10.0 A @ 125/250
VAC and 2.5 A @ 6/12/24 VDC. The pressure switch
shall have a maximum service pressure rating of 250
psi (17.2 bar) and shall be factory adjusted to operate
at a pressure of 4 to 8 psi (0.27 to 0.55 bar) with adjust-
ment up to 15 psi (1.03 bar). Switch shall be provided
with a ½” NPT male pressure connection. Low air su-
pervisory switch shall be Potter PS10-2.
•
Pressure alarm switch to indicate water flow in system.
Pressure switch shall be [cULus Listed] [FM Approved]
and of the bellows activated type enclosed in a weather
proof NEMA 4/4X rated enclosure incorporating tamper
proof screws. There shall be two sets of SPDT (form
C) contacts rated 10.0 A @ 125/250 VAC and 2.5 A @
6/13/24 VDC. The pressure switch shall have a maxi-
mum service pressure rating of 250 psi (17,2 bar) and
shall be factory adjusted to operate at a pressure of 4
to 8 psi (0,27 to 0,55 bar) with adjustment up to the 15
psi (1,03 bar). Switch shall be provided with a 1/2” NPT
male pressure connection. Pressure alarm switch shall
be Potter PS10-2.
•
Pressure maintenance device for maintaining a con-
stant pneumatic system pressure regardless of pres-
sure fluctuations in the compressed air (or nitrogen)
source. The pressure maintenance device shall consist
of galvanized trim and brass parts, including a strainer,
a field adjustable air pressure regulator and associated
pressure gauge. The pressure regulator shall have an
adjustable outlet pressure range of 5 to 100 psi (0.34
to 6.8 bar). The pressure maintenance device shall
have a working pressure of 175 psi (12.1 bar). Recom-
mended supervisory pressure shall be 7 to 10 psi (0.5
to 0.7 bar). Pressure maintenance device shall be Reli-
able Model A.
Double Interlock Preaction System shall be Reliable Dou-
ble Interlock Type D Preaction System, Bulletin 750.
Pneumatic Supervisory Pressure Supply Op-
tions
Note:
See Reliable Bulletins 254 and 251 for complete infor-
mation on air and nitrogen regulating equipment.
Owner’s Air supply
Supervisory air supply shall be provided by an owner sup-
plied air system in conjunction with a listed automatic pres-
sure maintenance device, capable of maintaining a con-
stant system pressure regardless of pressure fluctuations in
the compressed air source.
Compressed Air Supply
Supervisory air supply shall be provided by an automatic
tank-mounted air compressor sized for the capacity of the
double interlock preaction system piping, and be capable
of restoring normal air pressure in the system within the
time limits specified by NFPA 13. Unit shall include a mo
-
tor mounted, oil-less, piston compressor, pressure gauge,
pressure switch, check valve, drain valve and safety relief
valve. Single-phase motor shall have internal thermal pro-
tection.
Nitrogen
Nitrogen cylinders provided by an approved source shall
provide the nitrogen supply. The nitrogen cylinder pressure
shall be regulated and supervised through the use of nitro-
gen regulating device and low-pressure trim kit. This device
shall consist of a brass, single stage pressure regulator,
equipped with high pressure inlet and low pressure outlet
gauges, and ¼” copper connection tubing with galvanized
¾” x ¼” reducer bushing. This kit shall include a low-pres-
sure switch with associated galvanized connection trim. As-
sembly shall be a Reliable Nitrogen Regulating Device. This
device is to be used in conjunction with the Reliable Model
A Pressure Maintenance Device.
Optional System Accessories
System Control Valve
Preaction system control valve shall be a slow close, [cU-
Lus Listed] indicating butterfly type valve with a pre-wired
supervisory tamper switch assembly. The valve shall be
rated for a working pressure of [300 psi (20.7 bar)]. System
control valve shall be for a [2” (50 mm)] Reliable RBVG But-
terfly Valve or [2½” (65 mm)][3” (80 mm)][4” (100 mm)][6”
(150 mm][8” (200 mm] - Reliable BFG-300 Butterfly Valve.
Detection System
To initiate actuation of the preaction system’s deluge valve,
a supplemental electric detection system shall be provided
[Insert applicable product specification].
Releasing/Control Panel
A releasing/control panel shall be used to operate the
preaction system. The releasing/control panel shall be a
conventional, microprocessor-controlled panel containing
two initiating device circuits, and waterflow and supervi-
sory inputs. Output circuits shall include alarm, waterflow,
supervisory, and releasing circuits. Mode of operation shall
be set for cross zoned operation, requiring both a detec-
tion device input and a low air pressure switch input (sprin-
kler operation) to energize the solenoid valve, causing the
deluge valve to operate. Releasing/control panel shall be
equipped with a local tone alarm to annunciate loss of AC
power, system trouble, circuit trouble, and low auxiliary DC
power supply. Panel shall be [cULus Listed] [FM Approved]
and be capable of providing power for compatible detectors
and auxiliary devices used. Audible alarms shall be able to
be silenced at releasing panel. Auxiliary DC power supply
shall consist of (2) 12-volt lead acid batteries of the same
ampere-hour rating, providing [60 hours – cULus Listed]
[90 hours – FM Approved]. Dry contacts shall be provided
for remote annunciation of alarm, trouble, and supervisory
panel signals. Main power supply to be a dedicated a 120
VAC / 60 Hz circuit.
7.
Summary of Contents for DDX
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