Preventing Cavitation in Process Control Valves

cutaway view industrial control valve special trim reduces cavitation
Special valve trim can help prevent
Courtesy Flowserve - Kammer
Cavitation in process control valves results from a rapid drop in pressure as liquid passes through the valve. The condition results in the formation of vapor spaces or bubbles within the valve cavity. When the bubbles move downstream into a larger cross-sectional area, velocity decreases and liquid pressure increases. The higher pressure now surrounding the bubbles causes them to implode, producing shockwaves which propagate through the liquid. These shockwaves can cause metal fatigue and excessive wear on the internals of the valve. The collapsing bubbles also make a discernible sound with accompanying vibration. The cumulative effects of cavitation can cause rapid deterioration of valve internals, resulting in reduced control function, frequent need for service, or premature failure.

There are ways to mitigate cavitation. Some involve changes in the process, others, incorporating a properly designed and selected valve with trim that reduces or prevents the conditions that cause cavitation. The paper below is authored by Flowserve, a globally recognized manufacturer of process control valves under several brand names, and provides an in depth examination of the causes of cavitation, then continues with explanation of how their specialty valves are designed to overcome the conditions that promote it. At Analynk Wireless, we are not in the valve business, but recognize many of our customers operate fluid processes and would find the knowledge useful. There are detailed illustrations showing specific valve trim features that impede cavitation.

Analynk Wireless manufactures a comprehensive line of wireless receivers, transmitters, and accessories that enable process operators to establish signal connections across the room, across the plant, and across the globe.