Pump cavitation is a destructive phenomenon that occurs in most pumps and the symptoms include excessive noise and high energy usage.
Cavitation is defined as the phenomenon of formation of vapour bubbles within a liquid due to rapid change in localised pressures. When a liquid flows in a region where its pressure drops below its vapour pressure, its state changes from liquid to gas, creating a bubble.
These low pressure bubbles cannot maintain their form as they are surrounded by a higher pressure fluid and they immediately collapse. Due to this collapse, a high pressure is created and the metallic surfaces surrounding it are subjected to these pressures, which subsequently causes pitting on the surface.
Ways to avoid cavitation in reciprocating pumps:
1. Design: Ensure that there are no sharp corners or curvatures of flow in the system while designing the pump.
2. Material: Cavitation resistant materials like Bronze or Nickel can be used.
3. Model Testing: Before manufacturing, a scaled down model should be tested.
4. Admission of air: High pressure air can be injected into the low pressure zones of flowing liquid to prevent bubble formation.