maintenance pump shall have a capacity and pressure rating of [_____]
L/second gpm at a discharge pressure of at least [_____] kPa psi.
2.17.6
Pressure Balancing Valve
**************************************************************************
NOTE: This valve is used in pumped proportioning
systems that do NOT utilize in-line balanced
pressure proportioners (ILBP).
**************************************************************************
Pressure balancing valve shall be diaphragm type for balancing AFFF
concentrate with water pressure. Valve body and other metallic components
normally in contact with the AFFF concentrate shall be of bronze or
stainless steel. Unit shall be rated for working pressure of 1379 kPa 200
psi and shall include a manual bypass and duplex gauge for monitoring water
pressure and AFFF concentrate pressure.
2.17.7
Pressure Sustaining Valve
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NOTE: A regulating valve is used in pumped
proportioning systems to maintain constant pressure
to in-line balanced pressure proportioners (ILBP).
Delete this paragraph for applications using
pressure balancing valves instead of ILBP's.
**************************************************************************
Pressure regulating valve shall be a pressure sustaining back pressure
type, hydraulically operated, pilot controlled, modulating type arranged to
maintain constant upstream pressure in the AFFF concentrate piping system
as the flow rate varies. Valve body and other metallic components normally
in contact with the AFFF concentrate shall be of bronze or stainless steel
construction. Valve body shall be designed with flat-faced flanges to
match flanges of the same nominal size. Valve shall pass the unused
portion of the AFFF liquid back to the storage tank under low system flow
conditions. Valve shall be sized to pass the full AFFF liquid pump output
of a single foam concentrate pump.
2.18
BALANCED PRESSURE PROPORTIONER (RATIO CONTROLLER)
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NOTE: Edit this paragraph to suit the type and size
or sizes of proportioners required. In-line type
proportioners can be used only with concentrate
pumping systems. The size of the foam proportioner
(ratio controller) used in closed-head sprinkler
systems is critical. If the proportioner is too
large, it may not correctly proportion at low flows,
and if it is too small, it may not correctly
proportion at high flows. A 150 mm (6-inch)
proportioner will be appropriate for most sprinkler
applications.
**************************************************************************
The proportioner shall be [a standard] [an in-line] balanced pressure type
unit capable of proportioning AFFF liquid at 3 percent, (3 parts
concentrate to 97 parts water by volume solution) at flow rates within the
flow range of the proportioner. Major components of the proportioner,
SECTION 13955A
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