5.
Pressurizing Line Connection
The water supply for the pushrod chamber must be pro-
vided a dedicated connection to the water supply piping.
Pressurizing lines for multiple Model DDX Deluge Valve
pushrod chambers must never be manifolded together.
Each Model DDX Deluge Valve must have its own pushrod
chamber pressurizing line connection.
This connection must be made on the supply side of the
water supply control valve. This can be accomplished by:
•
Using a tapped connection directly below or next to the
main water supply control valve using a welded outlet
or the appropriate mechanical fittings. A grooved-end
outlet coupling is one way to achieve this; or
•
Using a water supply control valve that has an available
threaded (NPT) supply-side tap design to allow for a di-
rect water supply connection to the Model DDX Deluge
Valve’s pushrod chamber.
Caution:
Reliable’s DDX valve is designed with an inlet re-
striction built into the pushrod chamber. It is important not to
introduce additional restrictions into the direct water supply
connection or the discharge from the pushrod chamber by
installing additional valves or improperly installing the cop-
per lines used in the trim of the valve.
Hydrostatic Testing of DDX Valves and DDX
Systems
As required by NFPA 13, fire sprinkler systems with work
-
ing pressures up to and including 150 psi are to be hydro-
statically tested at a water pressure of 200 psi. Fire sprinkler
systems with working pressures above 150 psi are required
to be hydrostatically tested at 50 psi above the system work-
ing pressure. In addition to the hydrostatic tests described
above, dry pipe and double interlock preaction systems re-
quire an additional low pressure air test.
In some cases, hydrostatic testing (in accordance with the
NFPA 13 requirements noted above) will result in pressures
that exceed the working pressure of the valve and trim kit for
the two-hour test period.
The valve and applicable trim
kit have been tested, approved and listed under these
conditions and as such, hydrostatic testing in accor-
dance with NFPA 13 is acceptable. In addition, the
clapper can remain in the closed position and the trim
kit need not be isolated, as each has been designed to
withstand hydrostatic testing as required by NFPA 13.
Hydrostatically testing the valve and trim to pres-
sures higher than their rating is limited to the hydro-
static test as referenced by NFPA 13. It does not ad-
dress the occurrence(s) of a “water hammer” effect,
which can indeed damage the valve. A “water ham-
mer” in the water supply piping of the valve can create
pressures in excess of the rated pressure and should
be avoided by all necessary means. This condition
may be created from improper fire pump settings, un
-
derground construction work, or an improper venting
of trapped air in the water supply piping.
System Design Considerations
The automatic sprinklers, releasing devices, electric re-
leasing control equipment, fire detection devices, manual
pull stations, and signaling devices which are utilized with
the Type D Double Interlock Preaction System must be UL
or ULC Listed or FM Approved, as applicable.
Factory Mutual requires that detection devices in refriger-
ated areas be of the fixed temperature type. In addition,
they must have a temperature rating lower than that of the
sprinklers and preferably as low as possible for the given
ambient conditions.
The Deluge Valve, and all interconnecting piping must be
located in a readily visible and accessible location and in an
area that can be maintained above 40ºF (4ºC).
Note:
Heat
Tracing is not permitted.
Pendent sprinklers, other than dry pendents, used on pre-
action systems shall be installed on return bends per NFPA
13.
The solenoid valve must be operated and the system su-
pervised by a listed releasing control panel.
System Air Pressure Requirements
In accordance with NFPA 13, Double Interlock Preaction
Systems require a minimum of 7 psi (0.5 bar) pneumatic
pressure to supervise the sprinkler system. The Reliable
Model A Pressure Maintenance Device is used to maintain
the system pneumatic pressure between 7 and 10 psi (0.5
and 0.7 bar) where a dry nitrogen gas supply or a clean, de-
pendable and continuous (24 hours a day, 7 days a week)
compressed air source is available.
To adjust the system pneumatic pressure between 7 and
10 psi (0.5 and 0.7 bar) refer to Reliable Bulletin 251. The
low air pressure alarm switch is factory set to operate be-
tween 5 and 6 psi (0.3 and 0.4 bar) on decreasing pres-
sure. If necessary, adjustments can be made by following
the manufacturer’s adjustment procedure as described in
the installation and maintenance instructions.
Note:
The dew point of the air supply must be maintained
below the lowest ambient temperature to which the double
interlock preaction system piping will be exposed. Introduc-
tion of moisture into the system piping that is exposed to
freezing temperatures can create ice blockage, which could
prevent proper operation of the sprinkler system. As a mini-
mum, the air supply of air should be taken from the refriger-
ated area at the lowest temperature. The air supply sys-
tem must be carefully designed to prevent plugging by frost
deposits. Special requirements such as those in FME&R
Installation Guidelines for Refrigerated Storage may need to
be incorporated.
Each Type D Double Interlock Preaction system is provid-
ed with a Reliable Model A Pressure Maintenance Device
for individual monitoring of pneumatic pressure and proper
operation of the system. The Reliable Model A Pressure
Maintenance Device requires a tank mounted air compres-
sor.
Summary of Contents for DDX
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