Impeller balancing and inspection are imperative to the smooth operation of your pump

Impeller balancing and inspection are imperative to the smooth operation of your pump

Impeller balancing and inspection are imperative to the smooth operation of your pump. John A Kozel, President of SIMS Pump Company, shares some insights on how impeller imbalance can cause premature bearing, ring, mechanical seal and motor failure.

Like the pendulum on a clock, the impeller acts as a weight at the end of the shaft and starts to wobble, or deflect, explains Kozel. "Any corrosion, erosion, or cavitation increases the pendulum effect problem! The motor bearings cannot hold the stresses that are set up by the pendulum effect and the mechanical seals, sleeves, bushings, motor bearings, and motor fail prematurely. In extreme cases, the shaft can even break." He says it does not matter whether a pump is horizontal, or vertical, the weight, and inherent mechanical and hydraulic imbalance of cast metallic impellers (even when they are brand new) sets up a condition for premature bearing, ring, mechanical seal and motor failure.

“Bearing and mechanical seal failures are directly proportional to the rotor weight, speed, the amplitude of the mechanical imbalance, as well as the radial loading on the shaft as a result of hydraulic imbalance. Cast impellers have several problems, which directly relate to premature bearing and seal failure.” According to Kozel, the extremely high rotational speed of an impeller means that if it is vibrating, this could be the result of misalignment and unbalance, causing critical damage to other components and bearings. Speaking during a recent conference Kozel asked how long a motor would last without an impeller. "The answer is indefinite if it does not have a heavy unbalanced impeller at the end of the shaft. If it has a lightweight impeller that does not go into imbalance mechanically or hydraulically then it will last indefinitely," he said. "And that is the goal." The American headquartered Sims Pump Company has been a leader in pump technology for a century. The company has an excellent reputation for offering innovative solutions for marine and industrial pump applications and specialises in solving balance, cavitation, corrosion,