With and Without - Case Studies Using Air Valves to Mitigate Transients


  • Crystal Broadbent, P.E., Bo Copeland, P.E. - Hazen and Sawyer

Computer software programs now allow for easier, more comprehensive study of transient pressures and evaluation of the devices that mitigate transients. Devices commonly used for transient mitigation include: control valves, check valves, surge relief valves, surge vessels, and air valves. When selecting and sizing these devices, it’s important to understand the functionality and limitations of each.

This paper focuses on air valves and the interaction of air valves with other surge control devices. The discussion explains several types of air valves, including air release, air/ vacuum, air combination and three stage or anti-surge air valves. The presentation demonstrates air valve applications with three case studies that:
1. Compare performance of air/ vacuum valves versus anti-surge air valves, and anti-surge air valves with and without a surge relief valve.
2. Evaluate performance of a system using a surge vessel with and without air valves.
3. Assess use of air valves, surge vessel, and check valve modifications to mitigate transients due to power loss.

The case studies show that properly selecting and sizing air valves is an essential part of a transient protection system. Air valves alone may not provide adequate protection, but air valves in combination with other devices can effectively mitigate transients.

For more information, please contact the author at cbroadbent@hazenandsawyer.com.

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