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Today's automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for information about the CCST program. This question comes from the Level I study guide, Domain 3, Troubleshooting. Level I represents a professional who has a five-year total of education, training, and/or experience.
Which of the following parts of a globe valve serves the same purpose as the disk in butterfly valve?
a) seat
b) plug
c) packing rings
d) packing flange
e) none of the above
A butterfly valve has a circular body and a rotary-motion disk-closure member, which pivots on a stem, which runs up the middle of the disk. This disk with the stem looks roughly like the wings of a butterfly and thus its name. The disk physically blocks the flow of fluid through the valve body.
The parallel and the physical blocking mechanism in a globe valve is the plug. A globe valve has a linear motion, push-pull stem, and the plug closes to a seat to block the passage of fluid.
The plug and disk are both "closure members." The correct answer is B.