Gene Vogel
EASA Pump & Vibration Specialist
It’s common to find pump impellers with significant surface damage. The three most common causes of surface damage are erosion, corrosion and cavitation. For each of these there are characteristics which will help indicate the primary cause of the damage.
A brief description of each of the three phenomenon will be helpful:
- Erosion is the simplest; it is simply the wear to the impeller surfaces from abrasive materials suspended in the pumpage.
- Corrosion is also straightforward; corrosion is a chemical reaction between ionized molecules in the pumpage and metallic elements of the impeller. Oxidation is the most common corrosion on pump impellers.
- Cavitation is a more complex phenomenon. Cavitation is all about bubbles forming and imploding in the pumpage due to the pressure changes that occur as the pumpage flows through the impeller. Low pressure at the suction allows vapor bubbles to form and then these bubbles implode as the pressure increases through the impeller.
The appearance of the damage to the impeller surfaces reflects the characteristics of the each of these three phenomenon.
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