ISA Certified Control Systems Technician (CCST) program

CCST

Certified Control System Technicians (CCSTs) calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables.

CCST question

A magnetic flow meter determines the flow of a process material by measuring the _____ of the fluid.

A. velocity
B. density
C. volume
D. temperature

CCST Answer

The correct answer is A: "velocity".

Magnetic flowmeters measure the velocity of conductive liquids in pipes, such as water, acids, caustic, and slurries.

Faraday’s Law states that a flow of a conductive liquid through a magnetic field will cause a voltage signal to be sensed by electrodes located on the flow tube walls. Faraday’s Law also states that the voltage generated is proportional to the velocity of the flowing liquid through the magnetic field.

Since the flow tube diameter is fixed, once the velocity is known, it can be multiplied by the cross-sectional area of the flow tube to yield a volumetric flow rate.

Reference: Goettsche, L.D. (Editor), Maintenance of Instruments and Systems, 2nd Edition (2005), ISA Press