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Bermad Model 790 - Burst Control Valve

The Model 790-M Burst Control Valve is a hydraulically operated, diaphragm actuated control valve that upon sensing flow in excess of setting shuts off and locks drip tight until it is manually reset. As long as the flow is lower than the setting, the valve remains fully open, minimizing head loss.


Features and Benefits

  • Line pressure driven – Independent operation
  • Mechanical flow stem
    - Field adjustable
    - No moving parts
    - No electronic components
  • Highly sensitive hydraulic pilot
    - Requires minimal valve-ΔP
    - Tight setting window
  • In-line serviceable – Easy maintenance
  • Double chamber
    - Moderated valve reaction
    - Protected diaphragm
    - No spring - Full opening
  • Flexible design – Easy addition of features
  • “Y” or angle, wide body – Minimized pressure loss
  • Obstacle free, full bore – Uncompromising reliability

Major Additional Features

  • Closing at pressure drop – 790-91
  • Pressure reducing – 792-U
  • Solenoid control – 790-55-M
  • Electric override – 790-59-M


The Model 790-M is a pilot controlled valve equipped with an adjustable, 2-Way, high sensitivity, differential pressure sustaining pilot.

The pilot [1], senses valve differential pressure.

Should that pressure rise above pilot setting, the pilot opens, introducing upstream pressure into the upper control chamber [2], causing the main valve to begin an irreversible “close & lock” process. Opening and resetting the main valve requires manual intervention by means of the manual reset valve [3]. When differential pressure is below pilot setting, the pilot blocks upstream pressure from the control chamber, and the main valve remains fully open.

The manual test valve [4] enables simulation of burst conditions and valve response. After testing, reset procedure is required. The mechanical flow stem [5] enables adjusting the closing point, to meet various flow regimes.

Pilot System Specifications

Standard Materials:


Body & Cover: Brass or Stainless Steel

Elastomers: Synthetic Rubber

Spring: Stainless Steel

Internal parts: Stainless Steel

Diaphragm Covers: Fusion bonded epoxy coated Steel or Stainless Steel

Tubing & Fittings: Stainless Steel 316 or Copper & Brass

Accessories: Stainless Steel 316, Brass and Synthetic Rubber Elastomers


  • Burst flow settings should be at least 25% higher than the maximum allowed system flow
  • Recommended continuous flow velocity: 0.3-6.0 m/sec ; 1-20 ft/sec
  • Minimum operating pressure: 1.0 bar ; 14.5 psi. For lower pressure requirements consult factory

Typical Applications

Burst Control Valves in a Network

Every water system is vulnerable to bursts, whether due to system problems or external mechanical damage. This illustration shows a reservoir feeding a downhill line with lower elevation consumers. In case of burst, each Model 790-M protects against flooding lower elevation consumers.

The Model 790-M, installed at the reservoir outlet, also protects against reservoir emptying.

Typical Installation

Technical Data

Size Range: DN40-900 ; 11/2–36”

End Connections (Pressure Ratings):

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

Threaded: BSP or NPT

Others: Available on request

Valve Patterns: “Y” (globe) & angle, globe (DN600-900 ; 24”-36”)

Working Temperature: Water up to 80°C ; 180°F

Standard Materials:

Body & Actuator: Ductile Iron

Internals: Stainless Steel, Bronze & coated Steel

Diaphragm: Synthetic Rubber Nylon fabric-reinforced

Seals: Synthetic Rubber

Coating: Fusion Bonded Epoxy, RAL 5005 (Blue) approved for drinking water or Electrostatic Polyester Powder

How to Order

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

  • Size
  • Main model
  • Additional features
  • Pattern
  • Body material
  • End connection
  • Coating
  • Voltage & main valve position
  • Tubing & Fittings materials
  • Operational data (according to model)
  • Pressure data
  • Flow data
  • Reservoir level data
  • Settings

PDF Datasheets

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Engineering Data*

2D CAD Drawing

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

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Product code

Bermad Model 790 - Burst Control Valve

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