This month's segment in the series "The Fundamentals of Pumped Water Systems" looks at performance charts.
This is the third segment in a series on pump selection and pump performance curves and charts. In our last two articles, we discussed factors that should be considered when selecting a ground water pump, when to use a jet pump vs. a submersible, how to convert from feet of head to psi, how to read performance curves, how performance curves are generated and how to estimate the cost of operation of a pump. This month, we will look at performance charts - another way to evaluate the performance characteristics of a ground water pump.
The first two columns show the model number and HP, and the third column lists the delivery pressure in psi. This value is the pressure available to fill the pressure tank and shut off your pressure switch. You should choose a pump that has enough capacity to provide more than enough pressure to shut off the pressure switch and to allow for a drop in the pumping level and/or the eventual deterioration of the pump's performance. If you have a 20/40-pressure switch, choose a pump that gives you 50 psi at the desired flow rate and pumping level.