Tuesday, September 29, 2015

What Cavitation Looks Like, and How It Effects Your Valve

Cavitation is the formation of "bubbles" caused by rapid changes in pressure. It is a significant cause of wear metallic on surfaces in process piping, valves, pumps and instruments. As the rapid change in pressure takes place, the bubbles (voids in the liquid) collapse (implode), and expose the surrounding metal surfaces are repeatedly stressed by these implosions and their subsequent shock wave.

The consequences for a control valve as well as for the entire control process vary and are often destructive and may include:
  • Loud noise
  • Strong vibrations in the affected sections of the plant
  • Choked flow caused by vapor formation
  • Change of fluid properties
  • Erosion of valve components
  • Destruction of the control valve 
  •  Plant shutdown
This video provides a visual demonstration, through clear piping and valve housing, what actually happens inside the piping system.

Here is an excellent paper by Samson Controls on cavitation and its effects on control valves.