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
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)
Advantage
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
Advantage
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
Advantage
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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