Approximately how much pressure head must a pump located at grade produce to pump water to a tank located 20 meters above grade?
A. 1 Bar
B. 2 Bar
C. 3 Bar
D. 4 Bar
This may look like a straightforward question, but looks can be deceiving. This question is grossly incomplete because it does not include whether the top, bottom, top of its influent piping, or some other reference is 10 meters above grade or if the tank is pressurized. In addition, flow rates and pipe sizes that affect friction losses are not presented.
That said, 10 meters of water column is equivalent to approximately one atmosphere, which is approximately 1 Bar so in this application approximately 2 Bar of pressure will be needed to begin to start flow (if friction losses are neglected). Answers A and B can be eliminated.
It is reasonable to conclude that more than 2 Bar of pressure will be required. How much more is dependent upon the details of the application.
Additional complicating factors
Additional factors can add to the pressure required. For example, what if a flowmeter and flow control valve are in the piping system? What if the piping takes a tortuous route to the tank? Pump sizing can be a multidiscipline activity that can quickly get complicated.
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. Spitzer has more than 40 years of experience and has written more than 10 books and 300 articles about flow measurement, instrumentation and process control. He may be reached at 845-623-1830 or at spitzerandboyes.com.