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Cavitation Demystified. STP (Standard temperature and pressure). Phase Diagram of Water. Cavitation – A Simple Process. Cavitation is the formation and subsequent implosion of vapor bubbles in a fluid Caused by significant pressure gradients within process equipment

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cavitation a simple process
Cavitation – A Simple Process
  • Cavitation is the formation and subsequent implosion of vapor bubbles in a fluid
    • Caused by significant pressure gradients within process equipment
    • Pressure gradients typically generated by high velocity flow around
      • Valves – throttling (partially closed valves)
      • Vanes – moving portions of pump impellers
      • Protrusions – pitot tubes, vortex shedders, etc.
pressure gradient formation
Arrows indicate flow direction

Fluid is compressed above vane creating a high pressure region

Fluid is rarified below vane creating a low pressure region

Behind this low pressure region is another high pressure region

Pressure Gradient Formation
  • Vapor bubbles do not implode symmetrically
  • Because of pressure gradients, they tend to implode towards hard objects
microjetting high speed photograph
Microjet has formed

Vapor bubble is in the

process of imploding

towards the nearby hard


Shockwaves generated by microjetting can be up to 145,000,000 psi

This pressure vastly exceeds the compressive strength of any metal alloy

Microjetting – High Speed Photograph
the alternative to rigid elastic
The Alternative to Rigid - Elastic
  • Cavitation energy can be dissipated two ways
    • Into a rigid metallic substrate
      • Plastic deformation
      • Ultimate compressive failure
    • Into an elastic substrate
      • Hook’s Law
  • We modified our Durable & Abrasion Resistant Elastomer to better withstand cavitation
belzona 2141 acr fluid
Belzona 2141 (ACR-Fluid)
  • Project sprung from a US Coast Guard request
    • Products had to survive 16+ hours in a high speed test
    • At the time, the best product lasted 12 hours
    • Second formulation Belzona submitted lasted 20 hours
    • Coast Guard currently in the process of coating all rudders with Belzona 2141 (ACR-Fluid) to resist the severe cavitation of their service


Hydro Runner at a small Canadian Power Plant


Mild cavitation was decreasing generating efficiency


Runner was coated with Belzona 2141 (ACR-Fluid Elastomer) to restore and maintain efficiency. After 2 years it is still in perfect condition.



ITT 3480 Impeller


Severe cavitation was necessitating a full rebuild every 3 months


Impeller received two coats of Belzona 1321 (Ceramic S-Metal) and a final coat of Belzona 2141 (ACR-Fluid Elastomer). Impeller now lasts 28 months between rebuilds!


Thank You Very Much