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

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 orifice plate is used to eliminate damming of material at the top or bottom of a pipe?

a) concentric
b) round-edged
c) quadrant-edged
d) segmental
e) none of the above


Click Here to Reveal the Answer

An orifice plate is a flow-path restriction used in flow detection. They are in a straight run of smooth pipe away from valves and fittings so they do not interfere with the restrictor and readings.

The pressures on opposite sides of the plate are different, and the difference in pressures is proportional to the flow rate.

Segmental and eccentric plates have many similarities as to function. The segmental portion of the orifice mitigates the damming of foreign materials on the upstream side of the orifice.

Eccentric orifice plates work to stop damming as well.

The best answer to this question is D, segmental.

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