AutoQuiz: Which Control Valve Style Is More Likely to Develop a Blockage?

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

Today’s automation industry quiz question comes from the ISA Certified Automation Professional certification program. ISA CAP certification provides a non-biased, third-party, objective assessment and confirmation of an automation professional’s skills. The CAP exam is focused on direction, definition, design, development/application, deployment, documentation, and support of systems, software, and equipment used in control systems, manufacturing information systems, systems integration, and operational consulting. Click this link for more information about the CAP program. The following question comes from the CAP study guide, Performance Domain III, System Design, Design, specify, and procure the hardware/software used in the system.

Which of the following control valve body styles is MOST likely to develop blockage in a paper pulp slurry service?

a) pinch
b) characterized ball
c) butterfly
d) globe
e) none of the above

   

Click Here to Reveal the Answer

A globe valve consists of a plug on the end of a stem that moves the plug onto a seat. Because of the body design of this valve, cavities in the body can easily fill with materials and develop blockage. Ball, butterfly, and pinch valve body style have straight-through flow, and they are less likely to develop blockage.

The correct answer is D, globe.

Reference: Bela Liptak, Instrument Engineers’ Handbook – Process Control, Volume 2, CRC Press, and ISA Press.

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