The Model 720 Pressure Reducing Valve is a hydraulically operated,
diaphragm actuated control valve that reduces higher upstream pressure
to lower constant downstream pressure regardless of fluctuating demand
or varying upstream pressure.
The Mode is a pilot controlled valve equipped with an adjustable, 2-Way pressure reducing pilot.
The
needle valve continuously allows flow from the valve inlet into the
upper control chamber. The pilot senses downstream pressure. Should this
pressure rise above pilot setting, the pilot throttles, enabling
pressure in the upper control chamber to accumulate, causing the main
valve to throttle closed, decreasing downstream pressure to pilot
setting. Should downstream pressure fall below pilot setting, the pilot
releases accumulated pressure, and the main valve modulates open. The
integral orifice between the lower control chamber and valve outlet
moderates valve reactions. The needle valve controls the closing speed.
The downstream cock valve enables manual closing.
The Pressure
Reducing Valve shall reduce higher upstream pressure to lower preset
downstream pressure regardless of fluctuating demand or varying upstream
pressure.
Main Valve: The main valve shall be a
center guided, diaphragm actuated globe valve of either oblique (Y) or
angle pattern design. The body shall have a replaceable, raised,
stainless steel seat ring. The valve shall have an unobstructed flow
path, with no stem guides, bearings, or supporting ribs. The body and
cover shall be ductile iron. All external bolts, nuts, and studs shall
be Duplex coated. All valve components shall be accessible and
serviceable without removing the valve from the pipeline.
Actuator:
The actuator assembly shall be double chambered with an inherent
separating partition between the lower surface of the diaphragm and the
main valve. The entire actuator assembly (seal disk to top cover) shall
be removable from the valve as an integral unit. The stainless steel
valve shaft shall be center guided by a bearing in the separating
partition. The replaceable radial seal disk shall include a resilient
seal and shall be capable of accepting a V-Port Throttling Plug by
bolting.
Control System: The control system shall
consist of a 2-Way adjustable, direct acting, pressure reducing pilot
valve, a needle valve, isolating cock valves, and a filter. All fittings
shall be forged brass or stainless steel. The assembled valve shall be
hydraulically tested and factory adjusted to customer requirements.
Quality Assurance:
The valve manufacturer shall be certified according to the ISO 9001
Quality Assurance Standard. The main valve shall be certified as a
complete drinking water valve according to NSF, WRAS, and other
recognized standards.
Network design requires establishing various
pressure zones due to topography, distances, demands, energy costs,
reservoir availability, etc. The pump supplies water to the network and
to the reservoir. System pressure is too high for the residential
neighborhood, requiring a pressure reducing system.
By-Pass Pressure
Reducing Valve saves on maintenance costs. The larger (more costly to
maintain) valve operates during peak demand. The smaller by-pass valve
cuts operating hours of the larger valve, achieving greater return on
investment. For high differential pressure systems, see BERMAD
publication 720-PD Proportional
Pressure Reducing Valve. For high
pressure systems, see BERMAD publication 820 Piston Actuated Pressure
Reducing Valve.
The gate valve is the most generally used valve in industry. Gate valves are well suitable for water, oil and gasoline services as well as a variety of other liquids. They are meant for on‐off flow control and should only be applied in the completely open or completely closed place. When completely opened, fluid through the valve is in a directly line, producing in minimum stress drop throughout the valve. China gate valve are bi‐directional and can be used for circulation in possibly way.