Pump Characterization

Objective To characterize pump performance and to extrapolate to a geometrically similar pump.

Procedure You will need to assemble a test apparatus that is instrumented appropriately. The last time we did this lab using 3/8” OD plastic tubing on the effluent of the pump without the flow control and solenoid valves. The pumps were submerged in the 4 L reservoirs. The discharge went to the volumetric detector. A pressure sensor was installed between the reservoir and the effluent of the pump. It was necessary to take into account the kinetic energy of the fluid in the discharge line (although the kinetic energy term was small relative to the static pressure term). The maximum flow rate was very small compared with the manufacturer’s data. The data obtained also did not agree well with the manufacturer’s data and we suspect that air in the pump decreased the pump’s output. Thus we recommend that the air be removed from the pump by siphoning water through the pump while moving the pump around to dislodge any air bubbles.

1) Measure the flow rate using a volumetric detector. 2) Measure the pump head using a 200-kPa pressure sensor. 3) Adjust a valve to vary the flow rate (and increase the head produced by the pump) 4) Disassemble a pump and measure the impellor diameter.

Table 1. Manufacturer specifications of Report the 1/35 Hp, 3200 rpm pump. 1) Plot pump head (m) as a function of Hea 1 6 1 1 flow rate (mL/s) using your data and the d in manufacturers data. ft 2) Plot waterpower (watts) as a function of Flow 3 1 4 0 flow rate on the same graph (use a 2nd y in axis) using your data and the gph manufacturers data. Comment on the motor power used to drive the pump relative to the maximum waterpower produced by the pump. 3) What additional information would you need in order to calculate the specific speed of the pump? 4) Plot pump head (m) as a function of flow rate (mL/s) for two pumps in series and two pumps in parallel. At what head is the flow rate the same for the two combinations? 5) Explain why the flow rate doesn’t double when placing two pumps in parallel. Under what conditions does the flow rate almost double? 6) Plot pump head coefficient as a function of pump flow coefficient using your data.

CEE 332: Hydraulic Engineering Spring 2005 Monroe Weber-Shirk 7) Calculate the maximum head that could be produced by this pump based on the velocity of the periphery of the impellor and compare with the maximum head produced by the pump. 8) Plot pump head (m) as a function of flow rate (mL/s) using your data for a prototype pump that is twice as large and operates at ½ the rpm as the model that you tested. 9) What is the pump Reynolds number (based on rotational speed and impellor diameter)?

CEE 332: Hydraulic Engineering Spring 2005 Monroe Weber-Shirk Lab Setup We did this lab using 3/8” OD plastic tubing on the effluent of the pump. The pumps were submerged in the 4 L reservoirs. The discharge went to the volumetric detector. A pressure sensor was installed between the reservoir and the effluent of the pump. It was necessary to take into account the kinetic energy of the fluid in the discharge line (although the kinetic energy term was small relative to the static pressure term). The maximum flow rate was very small compared with the manufacturer’s data. The data obtained also did not agree well with the manufacturer’s data and we suspect that air in the pump seriously decreased the pump’s output. This lab could be improved if we could develop a method to increase the flow rate through the pump and if we carefully removed air from the pump.

CEE 332: Hydraulic Engineering Spring 2005 Monroe Weber-Shirk