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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 is from the Level I study guide, Domain 1, Calibration. Level I represents a professional who has a five-year total of education, training, and/or experience.

Hydrostatic head is another way of expressing:

a) gallons
b) pressure
c) length
d) mass
e) none of the above 

Hydrostatic head − or simply head − is the pressure that a height of liquid sitting over a given point creates at that point. Because it measures in height, the units of head are lengths-millimeters, inches, meters, feet, and the like. Engineers in the old days often referred to their steam engines as having a "full head of steam," meaning high pressure.

The correct answer is B.

Image source: Hydroelectric dam by Tomia - Own work. Licensed under CC BY 2.5 via Commons.