Which of the following can be used as a flow calibration technique?
A. Compare a flowmeter with a flow laboratory standard.
B. Compare a flowmeter with a master meter.
C. Compare a flowmeter with a meter under test (MUT).
D. Verify electronic adjustments (zero/span).
E. Verify flowmeter dimensions.
Comparing a flowmeter with an MUT (Answer C) is incorrect because the flowmeter would be compared with itself.
Comparing the flowmeter with a flow laboratory standard (Answer A) and comparing the flowmeter with a master meter (Answer B) are wet calibration techniques in which the fluid actually flows through the flowmeter.
Verifying electronic adjustments (Answer D) and verifying the flowmeter dimensions (Answer E) are dry calibration techniques that are performed without flowing the fluid through the flowmeter.
Additional complicating factors
Wet calibrations are usually more difficult to perform, but they are generally more effective than dry calibrations. However, dry calibrations are used extensively on some flowmeter technologies, including the calibration of orifice plate flowmeters for the custody transfer of natural gas.
David W. Spitzer is a regular contributor to Flow Control and a principal in Spitzer and Boyes LLC, which offers engineering, seminars, strategic, marketing consulting, distribution consulting and expert witness services for manufacturing and automation companies. Spitzer and Boyes is also the publisher of the Industrial Automation INSIDER. He has more than 40 years of experience and has written more than 10 books and 400 articles about flow measurement, instrumentation and process control. Spitzer may be reached at 845-623-1830 or via spitzerandboyes.com. Click on the Products tab to find his Consumer Guides to various flow and level measurement technologies.
