Which of the following orientations can be used to install a Coriolis mass flowmeter to measure the mass flow of a liquid in a vertical pipe flowing up?
A. U-tube down
B. Inverted U-tube
C. Horizontal (parallel to grade)
D. Flag position
Coriolis mass flowmeters in liquid service must be completely full of liquid to measure accurately. The inverted U-tube orientation (Answer B) could accumulate gas and should not be used for liquid applications.
The U-tube down orientation (Answer A) and horizontal orientation (Answer C) could be acceptable but would entail modification of the upstream and downstream piping. The flag position (Answer D) would typically be most practical.
Additional complicating factors
Not all Coriolis mass flowmeters have U-tube geometry, and some of these geometries can allow gas to accumulate in the flowmeter.
For example, a Coriolis mass flowmeter with delta-shaped tubes can accumulate gas in the downstream (upper) portion of the tubes when mounted in a flag position (Answer D), so the upstream and downstream piping should be modified to mount the flowmeter with its delta-shaped tubes down (Answer A).
Similarly, a single-path, self-filling and self-draining Coriolis mass flowmeter that forms a loop, jumps up (sideways if mounted in flag position) and then forms another loop must be installed in the horizontal plane (Answer C) to remove all gas from the system because any other orientation can allow gas to accumulate in the flowmeter.
David W. Spitzer is a principal at Spitzer and Boyes, LLC, which offers engineering, focused market research, writing/editing white papers, strategic marketing consulting, distribution consulting, seminars and expert witness services for manufacturing and automation companies. Spitzer has written more than 400 technical articles and 10 books about flow measurement, instrumentation and process control. He can be reached at 845-623-1830 or via spitzerandboyes.com.
