AutoQuiz is edited by Joel Don, ISA’s social media community manager.

Today’s aAutoQuiz20150515utomation industry quiz question comes from ISA’s new course, Control Valve Mechanics and Operations from Analog to Digital. The class, which is offered June 22-26, takes a deep dive into the control valve’s mechanical composition, actuation and positioning accessories, including a detailed study of digital valve controllers. The class is hands-on and lab intensive, and is designed to offer a real-world, working knowledge of valve mechanical configurations, valve operations and positioner calibrations.

There is a two-stage phenomenon in liquid flow. The first step is the formation of voids and cavities within the liquid system when the line pressure falls below the vapor pressure. The second stage is the collapse or implosion of these cavities back into an all-liquid state when the line pressure recovers above the vapor pressure and this stage is called:

A) Cavitation
B) Abrasion
C) Erosion
D) Flashing
E) None of the above

Quiz Bonus: Use coupon code JUNTS18 when you register for the Control Valve Mechanics and Operations class and get a special 50% social media follower discount. Register at this page:


Click Here to Reveal the Answer

The correct answer is A.

The definition of cavitation:

  •  A two-stage phenomenon of liquid flow involving the formation of vapor bubbles and their subsequent collapse
  • The implosion of the vapor bubbles results in noise and can cause extreme damage to the valve
  • Under severe cavitating conditions, extremely hard control valve components have failed in a matter of hours

The steps to avoiding cavitation:

  •  Use anti-cavitation valves
  • Select high FL type trim (selecting a hardened trim will only prolong the service)
  • Relocate valve to a point of higher static pressure
  • Place an additional restrictor downstream
  • Size valve properly
  • Place valves in series

Want to learn more about control valves?  Sign up for ISA’s new course, Control Valve Mechanics and Operations from Analog to Digital. Use the special quiz discount code JUNTS18 when you register for the course to get the class for half off. Register at this page:


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