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Relief Valves

A range of pressure only, vacuum only and combined pressure and vacuum relief valves to alleviate the problems caused by the thermal effects and the filling and emptying of storage tanks and vessels.

Pilot Operated
Relief Valves

To provide accurate pressure relief when operating near to the design pressure of the tank and also to overcome the problems of backpressure generated at the discharge of the valve due to pipework, scrubbers etc.

Tank Blanketing Valves.jpg
Tank Blankenting

Dedicated to provide inert or rich 

blanketing of storage tanks to reduce harmful fugitive emissions of products 


Marvac manufacture an extensive range of products to protect low pressure storage tanks and vessels. These products help to prevent damage to the tank and also prevent the tanks contents from escaping, ensuring the safety of personnel and the surrounding environment.

Pressure/Vacuum valves are designed to limit the maximum pressure and vacuum that can exist in a tank. When a tank is being filled the gas (air, vapour, etc.), that filled the space above the liquid is compressed and if this pressure was allowed to exceed the design pressure of the tank, then it would explode. Also, if the temperature of the tank increases, then the effect of vapourisation and expansion would cause the pressure to rise. Conversely, emptying the tank, or a reduction in temperature, causes a vacuum to be created.

Emergency Vent

To provide over pressure protection in the event of the tank being subjected to fire exposure and to provide access to the vessel from the top for internal inspection.

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