Reliable DDX-LP PrePak Instructions For Installation, Operation Care And Maintenance page 4

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, ap-
proved and listed under these conditions and as such, hy-
drostatic testing in accordance 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 de-
signed to withstand hydrostatic testing as required by NFPA
13.
Subjecting the valve and trim to pressures higher than
their rating is limited to the hydrostatic test as referenced
by NFPA13. It does not address the occurrence of a "wa-
ter hammer" effect, which may damage the valve. A "water
hammer" in the water supply piping of the valve can cre-
ate 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, underground con-
struction work, or an improper venting of trapped air in the
water supply piping.
System Supervisory Pressure Requirements
The DDX-LP PrePak includes gauges indicating the air/
nitrogen and water pressures on the Model DDX-LP sys-
tem. Table A specifies the air or nitrogen pressure to be
maintained in the sprinkler system piping based on the wa-
ter supply pressure. The factory installed Pressure Mainte-
nance Device in the unit automatically regulates makeup air
or nitrogen flow to maintain pressure with normal leakage
from system piping, while restricting the flow of makeup air
or nitrogen to the system. Please note that when the optional
Model B1 Accelerator is to be utilized to expedite water-de-
livery time, the air or nitrogen pressure must be not less than
15 psi (1.0 bar).
Table A
Water Pressure Supervisory Air or Nitrogen Pressure in
psi (bar)
Maximum Not Less Than
20 (1.4)
50 (3.4)
75 (5.2)
100 (6.9)
125 (8.6)
150 (10.3)
175 (12.1)
200 (13.8)
225 (15,5)
250 (17.2)
Note: During system setup, a higher pneumatic pressure
may be required in order to properly set the Model LP Dry
Pilot Actuator.
The dew point of the air supply must be maintained below
the lowest ambient temperature to which the dry system will
be exposed. Introduction of moisture into the system piping
exposed to freezing temperatures can create ice blockage
which could prevent proper system operation. As a mini-
mum, the air supply should be taken from the area of lowest
temperature within the protected area. The air supply sys-
tem must be carefully designed to prevent plugging by frost
deposits. Special requirements, such as those in FME&R's
Sprinkler System, psi (bar)
Not More Than
10 (0.7) 14 (0.9)
12 (0.8) 16 (1.1)
13 (0.9) 17 (1.2)
15 (1.0) 19 (1.3)
16 (1.1) 20 (1.4)
17 (1.2) 21 (1.4)
18 (1.2) 22 (1.5)
19 (1.3) 23 (1.6)
21 (1.5) 25 (1.7)
22 (1.5) 26 (1.8)
"Installation Guidelines for Refrigerated Storage" may need
to be incorporated.
Nitrogen used in refrigerated area systems minimizes the
possibility of ice build-up and blockage inside the system
piping that could inhibit proper system operation. The dew-
point of nitrogen compressed to 20 psig (1.4 bar) pressure
is -46°F (-43.3°C), and -52°F (-46.7°C) when compressed
to 10 psig (0.7 bar). High-pressure nitrogen cylinders can
typically be rented from a local source, with rental fees vary-
ing by supplier and cylinder sizes. The calculated nitrogen
supply in lbs (kg) to pressurize various system capacities to
10 psi (0.7 bar) at different freezer temperatures is shown in
Table B.
If the Reliable DDX-LP PrePak is to be used with Nitrogen,
a Nitrogen kit is available as an option. A pressure switch is
used to monitor the nitrogen supply; the electrical contacts
on the pressure switch close when the nitrogen supply falls
to 100 psi (6,9 bar). The nitrogen source should be replaced
promptly upon operation of the pressure switch. If the nitro-
gen supply is not replaced, make-up air will come solely
from the unit's air compressor (if installed). Compressed air
is not considered dry air, and may create ice plugs in the
sprinkler system piping.
Table B
Freezer Temperature
System
Capacity
20°F 0°F
Gal. (L)
(-6.7°C) (-18°C)
250 1.90 1.90
(946) (.86) (.86)
500 3.64 3.80
(1891) (1.65) (1.72)
750 5.50 5.70
(2840) (2.50) (2.60)
1,000 7.30 7.60
(3785) (3.30) (3.44)
Note: To obtain required nitrogen supply (lbs.) for 15 psi (1.0
bar) or 22 psi (1.5 bar), multiply the tabulated values by
a factor of 1.5 or 2.2 respectively.
(1 bar = 100 kPa)
* When filled with the Rapid Air – Fill Shutoff Valve open.
If the air compressor in the Model DDX-LP PrePak is to
be used to initially fill the sprinkler system with air, the steel
enclosure door should remain open in order to provide maxi-
mum intake air flow to the air compressor. The air compres-
sor is connected to a storage tank. This tank functions as
a reservoir, providing make-up air to compensate for small,
intermittent leaks in the sprinkler system. It should be not-
ed that significant leaks may overburden this storage tank,
thereby causing the air compressor to continuously cycle
on and off.
The factory-installed system low air pressure switch may
need on-site adjustment to correspond with the air pressure
values found in Table A. Adjustment, if required, should be
made according to Potter Bulletin 5401564 included with the
4.
Approx.
Fill Time
-20°F -40°F -60°F
(-29°C) (-40°C) (-51°C)
2.00 2.10 2.20
(.90) (.95) (1.00)
4.00 4.20 4.40
(1.81) (1.91) (2.00)
6.00 6.30 6.60
(2.72) (2.86) (3.00)
8.00 8.33 8.80
(3.62) (3.78) (4.00)
(min.)*
1
2
3
4