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.
What flowmeter does not use an obstruction?
a) head meter
b) magnetic flowmeter
c) open channel meter
d) turbine meter
A magnetic flowmeter is a volumetric flowmeter, which does not have any moving parts and is ideal for wastewater applications or any dirty liquid, which is conductive or water based. Magnetic flowmeters will generally not work with hydrocarbons.
The operation of a magnetic flowmeter rests upon Faraday's Law, which states the voltage induced across any conductor as it moves at right angles through a magnetic field is proportional to the velocity of that conductor.
The fluid must be electrically conductive for the Faraday principle to apply.
The other meters in this list leverage some kind of wheel or obstacle that creates a pressure differential from which one ascertains a flow measurement.
The correct answer is B.
Wikimedia Credit: magnetic flow meter