With the NPSHr rating supplied with the pump, engineers only need to calculate the NPSHa on their own. Anyone can do this with the formula shown below:
NPSHA = HA ± HZ – HF + HV – HVP
HA is the atmospheric pressure affecting the surface of the liquid while it’s in the supply tank. Unless the system involves a closed tank, this is likely the local absolute pressure based on altitude. HZ measures the amount of vertical distance the slurry travels between the supply tank and the pump’s center line. Work from the lowest point the liquid can reach in the tank since draining the volume changes the NPSHa. HF accounts for friction caused by the piping between the tank and pump. Friction coefficients are recorded for most standard piping materials. HV reflects the velocity of the head found at the suction port. Many engineers leave this measurement out since it’s often very small. Finally, insert the HVP into the formula by measuring the vapor pressure of the liquid, which is based on its pumping temperature. Temperature fluctuates in many slurry pumping operations, so use the highest temperature since that will reflect the highest vapor pressure as well.
By using a simple formula to properly size slurry pumps with NPSH, users can keep them running for years with minimal maintenance and repairs. Preventing cavitation may take a little extra work in the beginning, but it will pay off for the entire lifespan of the slurry pump.
Through different hydrodynamic principles, EDDY Pump technology overcomes obstacles including cavitation/NPSH loss, seal failure and clogging. Cavitation, which affects a pump’s ability to deliver high percent solids while maintaining high production rates, is a constant problem in mining and other slurry pumping applications. Through different hydrodynamic principles, EDDY Pump technology can overcome cavitation, so the pump does not suffer from loss of suction or performance.
This phenomenon is accomplished through the synchronized eddy effect generated by the geometrically shaped rotor acting in sync with the hydrodynamic pattern of the volute. Tests show that there is no evidence of cavitation at speeds up to 2,000-rpm. The cumulative effect of this energy gives this pump a greater head than many pumps and the ability to pump more concentrated material over longer distances.
Instead of operating with an impeller, the EDDY Pump uses a patented rotor design, which can avoid wear and tear much longer than many traditional impellers commonly found in centrifugal and other pumps. Due to the shape of the rotor and larger tolerance between the volute, the pump ensures less abusive contact with the pumping material. Wearing plates and wear rings are also not needed to regulate efficiency, which eliminates the problem of wear rings coming into contact. When wear rings contact, it generates a high amount of friction, which produces heat that causes the rings to gall (friction weld). When galling occurs, the pump can seize.
For more information on EDDY Pumps, check out our Slurry Pump Models.
Want more information on Pump Parts? Click the link below to contact us.