Performance Testing of Small Water Pumps: A Versatile and Economical Laboratory Exercise for Engineering Technology Students

A laboratory exercise based on the performance testing of small consumer-grade water pumps provides a versatile and economical platform for teaching engineering technology students the basics industrial experimental testing practices. This exercise also provides a practical means for students to learn firsthand about the basic operating characteristics of centrifugal pumps and closely related devices such as centrifugal compressors and fans. This experimental platform provides ample opportunities for students to gain experience with pre-test planning and uncertainty estimation, with unanticipated situations that may arise during tests that may introduce measurement error, and with post-test statistical analysis of the derived pump performance parameters. As an example, in this experiment flow rate is determined by measuring the time it takes for a pump to discharge a measured volume of water at a fixed pumping height. The flow rate is thus derived from measurement of two variables, volume and time, each prone to sources of experimental error that are easily visualized by the students. Such tangible examples of experimental uncertainty go a long way in helping students to understand techniques such as the Kline-McClintock method of uncertainty estimation, since the Kline-McClintock method involves mathematics (partial derivatives) to which many engineering technology students have had little or no exposure. The equipment used consists of consumer-grade submersible pumps sold in home improvement stores that are intended for use in small fountains. With maximum head rises of about four feet and maximum flow rates of a few gallons per minute, quantities of water involved are small meaning that the testing can be carried out in minimally equipped lab spaces, in classrooms, and even outdoors. Other equipment consists of readily available measuring vessels, stopwatches, and hardware grade buckets and tubing. The pumps are nearly silent in operation, creating no noise issues on campus. Because of the low cost of purchase and operation of the pumps, each laboratory group can have its own test setup. It has been found beneficial to have lab groups swap pumps after a first round of tests. Comparisons of performance results obtained by different groups with a common pump allows for reflection on discrepancies that may have resulted from differences in experimental techniques, care taken with measurements, and differences in compensation for various sources of loss (such as hydraulic friction in the pump discharge tubing) which are not necessarily directly attributable to the capabilities of the basic pump