Quiz Corner: Measuring mass flow

Which of the following flowmeters can measure 0 to 100 kg/min of liquid flow?

Marina Demkina/iStock
Marina Demkina/iStock

Which of the following flowmeters can measure 0 to 100 kg/min of liquid flow?

A. Coriolis mass     

B. Differential pressure     

C. Magnetic         

D. Positive displacement    

E. Turbine              

F. Ultrasonic                   

G. Vortex shedder

Answer A is the straightforward answer to the literal question because kg/min is a mass flow, and Coriolis mass is the only flowmeter technology in the list that measures mass flow.

A less literal interpretation of the question would focus answers on what the flowmeter displays — not on what the flowmeter measures. In this interpretation, all of the flowmeters listed can display the flow in kg/min. However, with the exception of Coriolis mass, displaying the flow will typically be the result of a calculation based on a fixed density of the liquid. 

Additional complicating factors

The measurement of some fluids may be traditionally displayed in certain units. For example, reactor feed flows are often expressed in kg/min or lb/min — independent of what the actual flowmeter measures. This can be confusing, so we displayed mass units in our plant when the flowmeter actually measured mass flow, except where a strong precedent applied, such as steam flow.

David W. SpitzerDavid W. Spitzer

 

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.

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