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Waterworks

Bermad Model 770 - Flow Control Valve

The Model 770-U Flow Control Valve is a hydraulically operated, diaphragm actuated control valve that maintains pre-set maximum flow, regardless of fluctuating demand or varying system pressure

PRODUCT CODE:
770-XXX
SIZE RANGE:
40-1200mm

Features and Benefits

  • Line pressure driven – Independent operation
  • Hydraulic flow sensor (upstream installation)
    - No moving parts
    - No electronic components
    - No need for flow straightening
  • In-line serviceable – Easy maintenance
  • Double chamber design
    - Moderated valve reaction
    - Protected diaphragm
  • Flexible design – Easy addition of features
  • Variety of accessories – Perfect mission matching
  • "Y" or angle, wide body – Minimized pressure loss
  • Semi-straight flow – Non-turbulent flow
  • Stainless Steel raised seat – Cavitation damage resistant
  • Obstacle free, full bore – Uncompromising reliability
  • V-Port Throttling Plug – Low flow stability

Major Additional Features

  • Solenoid control – 770-55-U
  • Solenoid control & check feature – 770-25-U
  • High sensitivity pilot – 770-12-U
  • Pressure Reducing – 772-U
  • Level & flow control valve – 757-U
  • Pump & flow control valve – 747-U
  • Pump circulation & flow control valve – 749-U
  • Electronic control valve – 718-03

Operation

The Model 770-U is a pilot controlled valve equipped with an adjustable, 2-Way flow pilot and an orifice assembly. The needle valve [1] continuously allows flow from valve inlet into the upper control chamber [2]. The pilot [3] senses the differential pressure across the orifice plate [4]. Should this differential pressure rise above pilot setting, the pilot throttles, enabling pressure to accumulate in the upper control chamber, causing the main valve to throttle closed, and limiting flow to the pilot setting. Should orifice differential pressure fall below pilot setting, the pilot releases accumulated pressure causing the main valve to modulate open.

The needle valve controls the closing speed. The downstream cock valve [5] enables manual closing.

Engineer Specifications

The Flow Control Valve shall maintain pre-set maximum flow, regardless of fluctuating demand or varying system 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 flow pilot valve, an orifice plate, a needle valve, isolating cock valves, and a filter. The orifice shall be attached to main valve inlet. 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.

Typical Applications

Distribution Networks

System design starts from expected flow range that determines major system components:

  • Pump stations: Characteristics, location, quantity
  • Supply lines: Layout, class, size
  • Reservoirs: Location, volume, head

Significant deviation from designed flow range might disrupt water supply or even damage system components. Appropriate design, placement, and use of the Model 770-U protects the system from excessive flow. When pressure reducing is also required, choosing the Model 772-U, instead of the Model 770-U, completes the solution.

Pump Overload and Cavitation Protection

Protection against excessive demand that causes pump overload and cavitation damage, is achieved by sustaining pump flow within design specifications.

Since pump specifications vary, so do the required solutions:

  • When the pump curve (flow vs. ΔP) is relatively steep, pressure sustaining valves Models 730, 730R, and 736 are the most suitable.
  • When the pump curve is relatively flat, pump protection with respect to pressure is not sufficient. Protection according to flow is recommended. The Model 770-U is the most suitable.

Technical Data

Dimensions and Weights

Main Valve

Valve Patterns: “Y” (globe) & angle

Size Range: 11/2–32” (40-800 mm)

End Connections (Pressure Ratings):

Flanged: ISO PN16, PN25 (ANSI Class 150, 300)

Threaded: BSP or NPT

Others: Available on request

Working Temperature: Water up to 80°C (180°F)

Standard Materials:

Body & Actuator: Ductile Iron

Internals: Stainless Steel, Bronze & coated Steel

Diaphragm: NBR Nylon fabric-reinforced

Seals: NBR

Coating: Fusion Bonded Epoxy, RAL 5005 (Blue) NSF & WRAS approved or Electrostatic Polyester Powder, RAL 6017 (Green)

Control System

Standard Materials:

Accessories: Bronze, Brass, Stainless Steel & NBR

Tubing: Copper or Stainless Steel

Fittings: Forged Brass or Stainless Steel

Pilot Standard Materials:

Body: Brass, Bronze or Stainless Steel

Elastomers: NBR

Springs: Galvanized Steel or Stainless Steel

Internals: Stainless Steel

Orifice Assembly Standard Materials:

Body: Fusion bonded epoxy Steel or Stainless Steel

Orifice Plate: Stainless Steel

Sensing Ports: 1/8” NPT

  • Standard (calculated) differential pressure: 0.4 bar (5.5 psi)

Flow Pilot Valve Selection

  • Pilots are modified to differential remote sensing-model “DR”.
  • When minimum head loss is essential and flow velocity is higher than 1.0 m/sec, consider using the Model 770-j equipped with a pitot tube flow sensor and high sensitivity flow pilot #7.

Flow Chart

How to Order

Please specify the requested valve in the following sequence: (for more options please contact us)

Manual
Datasheet
Engineering Data*
* Note: For some products Manual or Engineering Data are available only upon request.

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Product code

Bermad Model 770 - Flow Control Valve

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