postheadericon What is Cavitation

postheadericon Cavitation

Changing of liquid to gas and suddenly back to liquid as a rapid collapse (implosion). Cavitation occurs when the pressure/temperature boiling point is reached, liquid turns to gas and then drops and the gas turns back to a liquid. Boiling water occurs at 212F at sea level pressure, seen as bubbles violently forming as the liquid turns to gas, however, at higher altitudes/lower pressures, water boils at a lower temperature. When the pressure drops (like inside a pump 'behind' the propeller), so does the required temperature drop to reach boiling and bubbles are violently formed, pressure returns causing the expanded liquid to gas to suddenly return to compressed liquid, tiny implosions and heat occur strong enough to erode metal.

 

postheadericon Anti-Cavitation Plate

Commonly found on water vessels (outboard boats) but is rather a miss conception. Properly named “anti-ventilation plate” as the plate helps to reduce the sucking down of air from above the propeller of a boat but can not stop cavitation. Cavitation and Ventilation both cause air gap for boat propellers to jump or jitter, the vibration causing loss of power while too much will cause the propeller to spin free referred to as “prop blow out”. Trimming down (governing top rpm) is the best defense to cavitation and the erosive damage to the propeller cavitation causes.

 

postheadericon Anti-Cavitation Valve

Liquid control valves designed to resist cavitation by reducing flow over objects and angles that create low pressure zones.

Example like Bermad's Wide Body (“Y” or Angle Pattern) valve which is Hydro-dynamically designed for efficient flow with minimal pressure loss. With a full bore valve port area clear of obstructions; no ribs or stem guides. Bermad's design increases capacity by 25% over standard globe valves.

For Mining application, the Bermad hYflow ‘Y’ Valve Body is a polypropylene constructed valve that meets rough service conditions with high chemical and resists causing cavitation. Having an end-to-end “look-through” design and full bore seat with unobstructed flow path. This anti-cavitation valve is free of any in-line ribs, supporting cage, or shafts, enables ultra-high flow capacity with minimal pressure loss.

Comparator of valve types:
Normal Throttled Isolation Valve/Orifice Plate valve type
- Very high maintenance due to cavitation and seat leakage
BERMAD Pressure Reducing Valve
+ Very low maintenance, since they are built for regulation (anti-cavitation)

Benefits or Applications:
* Protection against damage caused by cavitation
* Reducing “Noise” caused by the violent action of cavitation in valve and pipe
* Help protect against valve or pipe “Bursting”
* System maintenance savings

 

postheadericon Anti-Cavitation Cone

Primarily used in jet ski, Anti-Cavitation Pump Cone will reduce overall internal pump cavitation in an offset reduction/compression nozzle design. The manufacture's reduction and compression nozzles are offset, while the manufacturer's pump cone and bearing cap remains straight which causes uneven pressures within the pump and reduction nozzle. An Anti-Cavitation Cone is offset and reshapes the output of the reduction nozzle promoting even pressures, which will substantially reduce cavitation, increase pump grab, boost acceleration, and increase top speed and performance by pushing back against low pressure zones. See anti-cavitation devices

 

postheadericon Anti-Cavitation Check Valve

Whenever the downstream pressure of a valve falls below the vapor pressure of the liquid being controlled at the conditions of “flow (pressure) and temperature” then FLASING occurs, liquid vaporizes. Cavitation occurs when liquid goes “below” the vapor pressure level and then recover to a pressure higher than the vapor pressure level and thus returns to liquid suddenly. Anti-cavitation Check Valve monitors pressure at the low state and regulates at either the high state point or at the inlet to balance pressure levels. See Bermad 700 – C2 Anti-Cavitation Valve to understand how Bermad has solved this issue for Mining and Waterworks with high demand and chemical control in a more efficient design.

 

postheadericon Anti-Cavitation Trim

Anti-cavitation trim is a method of fighting cavitation in valves used under extreme pressure differentials and high velocity flow conditions. Seat and disc as interlocked sleeves containing radial slots that deflect internal flow to push against itself, thus dissipating potential noise and cavitation damage. Radial slots create a larger flow path than is possible with the standard drilled holes typically employed by none trimmed anti-cavitation valves.

 

postheadericon Anti-Cavitation Device

Devices designed to reduce low pressure zones caused by obstructive objects that would reduce the flow of liquids or lower the temperature of the liquid. In either case, to avoiding liquid boil to gas and eliminate the damage caused by the sudden return of gas to liquid known as cavitation. See anti-cavitation cone, anti-cavitation trim and anti-cavitation check valve.

 

postheadericon Anti-Cavitation Additive

Chemical property designed to raise the boiling temperature point and/or lower the boiling pressure point of a liquid.

 

postheadericon Anti-Cavitation Valves Hydraulic

Valves designed to reduce cavitation in hydraulic systems where the gas form of a liquid can cause loss of control, loss of power due to “air gap” or even hazardous conditions as the implosion of cavitation results in instant high temperatures.

 

postheadericon Anti-Cavitation Plate Height

See anti-cavitation plate above for explanation of this term. See also your out board motor manufacture’s website for recommendations on anti-ventilation plate heights, positioning and manufacture recommendations.