David W. Spitzer
David W. Spitzer



What piping orientations are acceptable for a flowmeter to measure the flow of an 80/20 mixture of a liquid having a specific gravity of 0.80 and water?  

A. Flow up

B. Flow down

C. Flow horizontal

D. All of the above

Commentary
If the component liquids were miscible to form a homogeneous fluid, any orientation within the limits of the flowmeter technology would be possible.  Answer D would appear to be correct.  
    
However, oil and water are generally not miscible, so separation of the oil and water could occur in the horizontal piping upstream of the flowmeter. This can affect flowmeter performance because the liquid entering the flowmeter would not be homogeneous. Answer C is not necessarily correct. 
    
Locating the flowmeter in a vertical pipe flowing upward mitigates the potential separation problem encountered in horizontal pipe. However, it does not ensure that the flow is homogeneous because the oil and water may have already separated upstream of the vertical pipe. Answer A is not necessarily correct.  Similarly, locating the flowmeter in a vertical pipe flowing downward will cause Answer B to not necessarily be correct. 

Additional Complicating Factors
There is no definitive correct answer. Such flow measurement applications should be engineered carefully on an individual basis.  

David W. Spitzer is a regular contributor to Flow Control magazine and a principal in Spitzer and Boyes, LLC, offering engineering, seminars, strategic, marketing consulting, distribution consulting, and expert witness services for manufacturing and automation companies. David has more than 35 years of experience and has written over 10 books and 250 articles about flow measurement, instrumentation and process control. 

David W. Spitzer is a regular contributor to Flow Control magazine and a principal in Spitzer and Boyes, LLC offering engineering, seminars, strategic marketing consulting, distribution consulting and expert witness services for manufacturing and automation companies. He has more than 35 years of experience and has written over 10 books and 250 articles about flow measurement, instrumentation and process control.

Mr. Spitzer can be reached at 845 623-1830 or 
www.spitzerandboyes.com. Click on the “Products” tab to find his “Consumer Guides” to various flow and level measurement technologies.