|David W. Spitzer|
My initial gut reaction is that this piping installation was laid out by a piping designer with minimal or no input from an instrumentation engineer or instrument designer.
Why? People familiar with flow measurement know that most flowmeters require a good velocity profile upstream of the flowmeter to measure accurately. Insufficient downstream straight run can affect the measurement but not nearly as much. As such, instrumentation engineers and instrument designers tend to increase the upstream straight run and reduce the downstream straight run. In short, their objective is to measure flow accurately.
Piping designers route pipes to transport fluids from Point A to Point B. Although they may be aware of straight run myths (such as 10D upstream and 5D downstream), they are not focused on accurate measurement. Given free reign, they often locate flowmeters (and other devices) in the middle of the straight run—often for easy access and/or aesthetic purposes. In short, their objective has little to do with measurement accuracy.
Additional Complicating Factors
My initial assessment above is sometimes not correct. Certain flowmeters have no straight run requirements. They can be located anywhere in the run, but they can be easier to access and more aesthetically appealing when located in the middle of the run.
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. Spitzer and Boyes is also the publisher of the Industrial Automation Insider. 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.