• Certification Review
ISA Certified Control Systems Technician (CCST) program

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

The Reynolds Number for a flowing fluid is most affected by which of the following parameters?

A. viscosity
B. pressure
C. friction factor
D. temperature

CCST Answer

The correct answer is A, "viscosity." The Reynolds Number for a flowing fluid can be generalized as the ratio of kinetic (or inertial) forces divided by viscous forces. Although friction factor and temperature do affect inertial forces and viscosity to some degree, and therefore, Reynolds number, viscosity has the most direct effect upon the value of the Reynolds Number.

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

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