Pumps - More Than The Basics : Whitley Burchett

Pumps: More than the Basics
(Presented at CWEA San Francisco Bay Section Professional Development Seminar,
Berkeley, CA, August 2005)

Tom Hendrey: Whitley, Burchett & Associates

ABSTRACT

How Systems Affect Pumps: The topic presented the importance of looking at a range of potential system curves when selecting pumps and developing pump control strategies. Often pumps are selected on the basis of a single calculated system curve. In fact, the friction resistance of a system will not be known with certainty during design and even if it was known, it will likely change over the many year operating life of the system. Similarly, static heads are frequently not static but rather they vary over a range of "static" heads. If these uncertainties are not considered during pump selection, the pump may end up operating far away from its best efficiency point with greater potential for damage and reduced pump life. Even with a well selected pump, the control of multiple pumps in parallel must consider the shape and uncertainty in the system curve to develop the best operating strategy of when to add or delete multiple pumps or to change the speeds for variable speed pumps. An example of the effect of system curve on control strategy was presented.