Signs that Cavitation is Happening
The most obvious signs of cavitation are vibration and noise during system operation, often sounding like the pump is being filled with bits of gravel. Other signs of cavitation include a reduction in discharge pressure or flow, increased power consumption and debris in the discharge liquid.
Applications that Feature Cavitation
While cavitation can occur in a wide variety of applications, it most often occurs when transferring fluids with high vapor pressures, such as liquefied petroleum gas (LPG), anhydrous ammonia (NH3), gasoline, acetone, various types of refrigerants and condensates, and those that are highly viscous. These applications are more susceptible to cavitation because the vapor pressure of these liquids is greater than any NPSH provided. In other words, these applications operate at a deficit from the start: the liquid demands more than what the system could ever provide.
Negative Effects of Cavitation on Pumps
If cavitation-causing conditions are present in an operation and allowed to persist, damage to the pump and its components is almost certain to occur. In fact, cavitation damage could set off a chain reaction of negative effects that can include loss of operational efficiency, elevated maintenance and part-replacement costs, pump downtime and, in the worst-case scenario, total pump failure.
Dynamic components are especially sensitive to cavitation. Specifically, the pump’s mechanical-seal faces will briefly separate as the implosions occur. The shock-wave pulsations create a condition known as “chattering,” which leads to premature wear and failure of mechanical seals. Additional failure should be expected in other wetted parts, such as bushings, impellers, back covers, volutes, casings, heads, gears, idlers, and vanes.