The Model 735-M Surge Anticipating Valve is an off-line, hydraulically operated, diaphragm actuated valve. The valve, sensing line pressure, opens in response to the pressure drop associated with abrupt pump stoppage. The pre-opened valve dissipates the returning high-pressure wave, eliminating the surge. The Model 735-M smoothly closes drip tight as quickly as the relief feature allows while preventing closing surge. The valve also relieves excessive system pressure.
The abrupt stopping of a pump produces a pressuredrop as the traveling column of water, with its inherentmomentum, continues to travel along the line,generating severe low pressure.When the traveling column of water loses itsmomentum, it travels back towards the pump. Shouldit hit the closed check valve, a very high pressuresurge is created and travels throughout the systemas a damaging wave at velocities of up to "Mach 4".No quick relief valve can react quickly enough toeliminate it.
Eliminating surge requires anticipation and pre-action. The Model 735-M is well suited to this task. The Low Pressure (LP) pilot [1] senses the initial pressure drop and opens. This immediate reaction allows remaining line pressure to quickly open the main valve.
The already opened Model 735-M releases the returning column of water, minimizing the line pressure rise. Should the relief rate be insufficient, and the pressure exceed the High Pressure (HP) pilot [2] setting, the pilot immediately opens, further opening the main valve.
As system pressure stabilizes again at static pressure, both pilots close and the main valve begins closing. Should line pressure rise during main valve closing, the HP pilot briefly stops the process, preventing the pressure from continuing to rise. The flow stem [3] limits the relief flow to prevent column separation and preserve closing pressure.
Cock valve [4] serves for selecting operating and sensing source:
In this system, a pump battery supplies the main line through a manifold. The Model 735-M:
Surge is the result of many factors: designed flow rate, pumping system, main line characteristics, etc. By using advanced mathematics and computer software, BERMAD’s experienced engineers can perform the desired analysis. For best analysis, all of the following data is required.
For systems with multiple pumping stations and/or multiple consumers along the supply line, the following data is also required:
This surge analysis indicates that without protection the system is exposed to:
Simulated surge protection recommends:
With full surge protection, the simulation shows no surge and minimal vacuum.
The Surge Anticipating Valve shall open in response to the pressure drop associated with abrupt pump stoppage to dissipate the returning high pressure wave, eliminating the surge. It shall smoothly close drip tight as quickly as the relief feature allows, while preventing closing surge. The valve shall also relieve excessive 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 two adjustable 2-way pilots, a needle valve, a flow stem, a cock valve, and a filter. All fittings shall be forged brass or stainless steel. The assembled valve shall be hydraulically tested.
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.
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)
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)
Standard Materials:
Accessories:mBronze, 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
Please specify the requested valve in the following sequence: (for more options, refer to Ordering Guide)
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