How to overcome cavitation damage in pumping applications
Cavitation is a common problem found in control valves and pumps in pumping applications. Cavitation is essentially rapid vaporisation and condensation within a liquid and occurs when the local pressure in a fluid reaches the level below the vapour pressure of the liquid.
Cavitation causes wear and tear and sometimes serious damage. This is know as Cavitation damage and it can dramatically reduce the lifetime of valves and system components.
Why is Cavitation harmful?
When local pressure falls to vapour pressure, vapour bubbles are formed. These bubbles travel to an area of higher pressure and then collapse with phenomenal force. Therefore, it is not the vaporisation which causes the damage; it is when the vapour immediately collapses after evaporation. This violent collapse and subsequent force causes noise, vibration, accelerated corrosion and limited valve flow.
What is cavitation damage?
The images below show cavitation damage in a control valve and on a pump impeller.
Cavitational damage is the side effects of Cavitation. Cavitation damage manifests itself as:
- Loud noise – the sound of popcorn crackling or gravel rumbling, resulting in noise pollution in neighbouring areas and risk of hearing damage.
- Strong vibrations – the shock waves caused by collapsing vapour bubbles produce pressure fluctuations which cause vibrations, which result in loosened bolts, fatigue metal and ultimately structural damage or valve failure.
- Erosion – cavitation can result in corrosion of the control valve and the downstream piping, which can be costly and time-consuming to replace.
- Restricted flow – as the vapour water displaced the liquid water, the capacity needed for the required flow rates can be seriously restricted.
Overcoming cavitation damage in control valves
Singer Valve’s Anti-Cavitation trim is one of the most innovative products on the market today and the most effective in overcoming cavitation damage in control valves.
Singer Valve Anti-cavitation trim
The Singer Valve Anti-Cavitation trim is comprised of 2 stainless steel sliding cages.
- The first cage directs and contains the cavitation recovery, allowing it to dissipate harmlessly.
- The second cage allows further control to a level as low as atmospheric pressure downstream.
The image below shows Singer valve’s Dual Anti-cavitation cages, which is designed to handle high pressure drops.
Each cage is designed and engineered to meet the flow/pressure differential of each application. This means the control valves are equipped to handle all flow rates and all pressure differentials, without the need of orifice plates.
Singer Valve’s Anti-Cavitation control valves mean cavitation damage can be avoided without having to increase downstream pressure by using an extra gate valve, butterfly valve or orifice plate.
To understand how Singer Valves’ Control Valves with Anti-cavitation trim overcame the problem of cavitation damage in a real life application, click here.
Has anyone had any experience of cavitation before? How did you ovecome the problem?
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