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WAM Middle East

Membrane Pressure Relief Valves VHS

The ultimate safety net against abnormal conditions inside bins or silos
Find out more about this product for Bakeries, Bakery Plants


Membrane Pressure Relief Valves 1
Membrane Pressure Relief Valves 2
Membrane Pressure Relief Valves 3
VHS Pressure Relief Valves are the last safety net when abnormal pressure conditions endanger the silo structure. This is why sudden excess or suction pressure inside the silo have to be dealt with instantly. Even though ideally a VHS Pressure Relief Valve should never have to go into action, it must be efficient and reliable if needed.
Innovative operating principle enabling instantaneous pressure balance
Innovative operating principle enabling instantaneous pressure balance
Time saving maintenance
Time saving maintenance
Dust emission recovery possible
Dust emission recovery possible

Technical Specs


VHS Pressure Relief Valves consist of a cylindrically shaped metal body with clamped connection spigot to the silo, an exhaust outlet spout for duct connection, an elastic membrane able to re-establish pressure balance instantaneously, a counterweight kit to keep the valve closed under normal conditions, and a weather protection cover.
Membrane Pressure Relief Valves


For some time, tighter safety regulations in industrialised countries have ensured stricter enforcement of rules regarding the safeguarding of silos and bins against excess and negative pressure. Soon other countries will probably follow this example.
The counterweight-loaded VHS-type Pressure Relief Valve has one decisive advantage over the other type offered by WAM, the VCP. Due to the moment of inertia of the helical springs on the VCP, pressure balance is re-established quickly but not instantaneously.
The VHS, on the other hand, does this in real time. Through an interplay of pressure on different surface areas on both sides of a membrane fitted inside the valve housing, perfect pressure balance is achieved. In the event of excess pressure this interaction enables air from inside the silo to flow back into the atmosphere, whereas in case of suction pressure the air penetrates from the atmosphere into the silo.


  • 304 stainless steel casing
  • Casing diameter: 273 mm (10 in)
  • Flow rate: up to 5,000 m3/h (2,950 cfm)
  • Exhaust outlet spout for connection with centralised suction system
  • Preset for maximum negative pressure of -0.005 bar (0.07 psi) and maximum excess pressure of 0.05 bar (0.72 psi).


  • Compact overall dimensions
  • Lightweight
  • Time saving maintenance
  • The operating principle of the VHS Pressure Relief Valve in itself is innovative. Its special double-acting membrane – pervious to air – sees to both excess and suction pressure relief.
  • Special properties of the membrane help avoid clogging, as well as formation of material crusts.
  • Dust emission recovery possible
  • Emission channelling


  • Non-standard settings optionally available
  • Inductive sensors
  • Bird net
  • Setting kit


VHS-C - Pressure Relief Valve
VCP VHS - Pressure Relief Valve


Here below you will find all documents regarding this product. Click "Other Languages" for translated versions.


Latest edition: January 0001
Code: 203001751
Latest edition: September 2012
French, German, Italian
Code: WAM.03042
Latest edition: September 2012
American english

Application Datasheets

Latest edition: December 2014
Latest edition: December 2014
Latest edition: April 2015
Latest edition: April 2015
Latest edition: January 2015
Latest edition: December 2014
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