Quiz Corner: Coriolis mass flowmeter orientation for vapor applications, part 1

Which of the following orientations can be used to install a Coriolis mass flowmeter to measure the mass flow of a condensable vapor in a horizontal pipe?    

1. U-tube down
2. Inverted U-tube
3. U-tube horizontal (parallel to grade)

Coriolis mass flowmeters in vapor service must be completely full of vapor to measure accurately. The U-tube down orientation (Answer A) could accumulate liquid and should not be used for vapor applications.

Few Coriolis mass flowmeters are mounted in the horizontal plane (Answer C), so mounting the flowmeter with an inverted U-tube orientation (Answer A) that hydraulically removes liquid from the flowmeter would be practical.

Additional complicating factors

Not all Coriolis mass flowmeters have U-tube geometry, and some of these geometries can allow liquid to accumulate in the flowmeter.

For example, a single-path self-filling and self-draining Coriolis mass flowmeter that forms a loop, jumps up and then forms another loop must be installed in the horizontal plane (Answer C) to remove all liquid from the system because any other orientation can allow liquid 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.