Field testing to verify manufactures performance claims is a sensible thing to do, but often difficult to perform. It’s difficult because:

  • Your recording instruments are not always accurate. They should be calibrated at regular intervals,
  • Velocity measurements are often difficult to take, and as a result are often ignored, but they are necessary, especially in low head pumps.
  • Pressure gauges must be placed at the proper points. They should be proceeded by at least five diameters of straight pipe and have no sharp edges at the inside wall of the pipe.
  • Pay close attention to the height of your gauges. If Bourdon gauges are used, the Z measurement is made from the center of the gauge.
    • If the pump takes its suction from an open surface, point 1 should be taken from on the surface of the liquid.

To get an accurate reading, all terms in the following total head equation must be considered.