Selection of bleeding and venting valves

Types and sizes of the bleeding and venting valves must be chosen in accordance with the air quantity to be discharged under working pressure. The working pressure range must be within the limits of the maximum operating pressure of the plant, otherwise the bleeding valve cannot open.

  • Bleeding and venting valves for continuous operation discharge from pipelines, vessels or systems small quantities of air or gas accruing during plant operation
  • Combined bleeding and venting valves discharge from pipelines, vessels and systems large air quantities during
    filling and small quantities of air or gas during continuous operation
  • Start-up bleeding and venting valves discharge large air quantities when pipelines, vessels or systems are filled

Know-How bleeding and venting valves

Mankenberg industrial valves - red line

Start-up bleeding and venting valves

Field of Application

Pipelines, vessels or systems with high volume flows, that are frequently filled or drained (for example marine loading pipelines)

Important Note

Does not open under pressure (remains closed during operation also when liquid is no longer present)


A large seat diameter allows for extreme flow rates within a short period of time at a low differential pressure, consequently, faster and safer start-up of plants (plant sections), prevention of vacuum shocks

Bleeding and venting valves for continuous operation

Field of Application

Plants in which air / gas should continuously be introduced or air entry cannot be avoided | installations containing liquids from which gas emanates during operation (pressure
reduction, temperature change)

Important Note

Fill or drain the system slowly | reduced throughput at small pressure | possibly insufficient protection from a vacuum


Discharges air / gas, that accumulates during operation, from the system without fluid loss | ensures efficiency of the system also when operated for long periods | prevents pressure surges

Combined bleeding and venting valves 

Field of Application

In systems that are frequently started and shut down, in which air/gas accumulates during operation (for example in surface mining)

Important note

The bleeding and venting performances for start-up and continuous operation are distinctly different from each other – functions must be checked separately


Combines the advantages of start-up and continuous bleeding and prevents vacuums and pressure surges with one single device – saves space and investment costs


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