Vacuum Relief Valve from Closed Line

Weight or Spring-Loaded Pressure/Vacuum Relief Valves

Application

Direct acting vacuum relief valves (also known as breather valves, conservation vents, or safety vents) are special types of relief valves which are specifically designed for tank protection. This unit allows vacuum relief from a closed line.

Pressure / vacuum relief valves are used extensively on bulk storage tanks, including fixed roof tanks with floating covers, to minimise evaporation loss. The valve prevents the build up of excessive pressure or vacuum which can unbalance the system or damage the storage vessel.

Principle of Operation

The valves have a cast body which is flanged for connection to the storage tank. The vacuum side is designed for connection to a closed line to allow control over the gas/vapour brought into the tank when under-pressure, thus protecting the contents of the tank from exposure to air.

The valve incorporates a pallet and diaphragm assembly which rests on an 'O' ring seal to prevent leakage. This 'O' ring can be removed and the seat machined optically flat, producing a metal to metal seating arrangement if required. The weight of the pallet pushes the diaphragm against the seat to keep it closed. When the vacuum increases, the pallet and diaphragm lifts and air/gas is allowed to flow. The vacuum side can be spring loaded for higher set pressures.

Benefits

• Vacuum relief valves provide high gas flow from a compact valve size
• Range of sizes and materials to suit a wide range of applications
• Wide range of vacuum settings to provide maximum tank protection
  whilst ensuring minimum gas loss
• Valve sizing service assists optimum valve performance/cost specification
• Multiple configuration options for venting from pipes or atmosphere
• The Elmac technical team can advise on specific location queries

General Layout

Material Specifications

* Special options and requests can be discussed with the Customer Services team.

Dimensions

^ Based on weight-loaded valve sizes. Contact Customer Services for spring-loaded valve sizes.
* Does not include pallet weights for pressure control.

Operating Limits

Variations

The pressure/vacuum relief valves are available in the following configurations:

• Pressure relief to atmosphere
• Pressure relief to closed line
• Pressure relief to atmosphere, vacuum relief from atmosphere
• Pressure relief to atmosphere, vacuum relief from closed line
• Pressure Relief to closed line, vacuum relief from atmosphere
• Pressure Relief to closed line, vacuum relief from closed line
• Vacuum relief from atmosphere
• Vacuum relief from closed line

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