Low NSPH Centrifugal Pumps for Educational Research Flume System

Enquiry from a Manufacturer of Educational Flow Channel Systems

It is important for engineering students to see real life examples of fluid mechanics for both educational and research purposes. Flume systems are a great way of displaying the practical impacts of altering the flow rate and pressure of pumps in an enclosed circuit. Having a transparent viewing screen, the effects of wave generation and regulating solids content can be displayed safely in real time.

A manufacturer of educational flow channel systems approached us with an unresolved problem they were facing, hoping that we had a solution. Their products are installed in various Universities and Colleges throughout the World and the centrifugal pump is a vital component, it is crucial that it is robust, reliable, and fit for purpose. Their current models were wearing prematurely due to cavitation and mechanical seal failure, a problem that other pump manufacturers were unable to solve.

Specifying our XCN100/160 Centrifugal Pump as a Long Lasting Solution

By discussing the issues with the customer, studying their design and the existing pump specifications, it was evident what the causes were. The installed inlet tank is small, and the pipework run is short, this does not change when either operating a closed loop or open loop experiment. The combination of these factors can lower the amount of NPSH available for the centrifugal pump, a very common cause of cavitation and dry running. The existing models were running at high speeds with 2 pole motors, meaning they were unable to operate correctly at low head/pressure and the NPSH requirements were too high for the flume systems. It is also possible for experiments to use sand particles on occasion, they are in small quantities, however over time these can wear a standard mechanical seal and cause loss of pressure and leakage, also damaging the motor if not discovered quickly.

With all the pertinent information we were able to specify a more suitable and long-lasting solution. Due to the low head requirements, low NPSH available and as these pumps can often run for several hours a day, we selected a larger unit installed with a slower 4 pole motor. The combination of a larger pump and slower motor lowers the discharge head and decreases the NPSH required, this significantly reduces the chances of cavitation and increases the lifespan of the wearing components inside the casing. In additional, we installed our XCN100/160 centrifugal pumps with hard faced mechanical seals and fitted the inside of the casing with a ceramic coating to make them more resistant to abrasion from the sand content present in certain tests.

Below are the specifications of the pumps that were supplied: 

Read our guides on Vortexing and the effects of low NPSH