This example shows a well jet pump installation. The well jet pump installation presented in this example consists of a surface-mounted centrifugal pump and a jet pump installed in the well below the surface of the water.
In this well jet pump installation, the distance between the centrifugal pump and water level is 36 feet. The jet pump installed in the well 1.5 feet below the surface of the water. See the schematic below.
The centrifugal pump discharge pressure is 20 psi and its delivery at nominal conditions is expected to be about 130 gallons/min. The pipe between the centrifugal pump output and the jet pump inlet has a 2 inch diameter and is 37.5 feet long. The diameter of the pipe connecting the jet pump output and centrifugal pump input is 4 inches, and it is 36 feet long. The centrifugal pump output is divided into two parts: one goes through the check valve into the tank, and the rest is diverted to the inlet of the jet pump. The delivery of the pump assembly must be greater than 25 gallons/minute. The centrifugal pump NPSH must be greater than 2 psi.
The jet pump parameters were initially determined based on recommendations provided in the Pump Handbook by Karassic, I. J., et al (third edition, 2001), and then modified to simplify the calculations. As a result, the primary flow rate () of the jet pump is 104.5 gpm, the secondary flow rate () is 26.5 gpm, and the output of the pump assembly () is 26.5 gpm.
The plots below show flow rates into and out of the jet pump and the volume of the water tank.