Today’s automation industry quiz question comes from ISA’s technical training course, Control Valve Mechanics and Operations from Analog to Digital. The course takes a deep dive into the control valve’s mechanical composition, actuation and positioning accessories, including a detailed study of digital valve controllers. Training 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.
When the percentage of flow through a valve equals the percentage of plug movement, a valve has:
A) Linear flow characteristic
B) Equal percentage flow characteristic
C) Quick opening flow characteristic
D) Curved flow characteristic
E) None of the above
Click Here to Reveal the Answer
If a valve with a linear flow characteristic is open to 20% of its maximum, then the flow through the valve is 20% of its maximum. As to an equal percentage valve, choice B, if it were open 20%, the flow would be less than 20% of its maximum. It might be only 5%, for instance.
Choice C, quick opening flow characteristic, would describe a valve that lets a lot of flow go through the valve just as it is opening. At 20% of full open for instance, the flow might already be 60% of its maximum-ergo the name quick opening. Choice D is not a flow characteristic.
The answer is A, linear flow characteristic.
Want to learn more about control valves? Sign up for ISA’s training course, Control Valve Mechanics and Operations from Analog to Digital.
About the Editor
Joel Don is the community manager for ISA and is an independent content marketing, social media and public relations consultant. Prior to his work in marketing and PR, Joel served as an editor for regional newspapers and national magazines throughout the U.S. He earned a master's degree from the Medill School at Northwestern University with a focus on science, engineering and biomedical marketing communications, and a bachelor of science degree from UC San Diego.