Cavitation

[kevn]

Hello all,

Looking for some help in understanding cavitation in water pumps from cause, effects and prevention.

Thanks,

Kev

[nike123]

Did you tried wikipedia?
http://grundfos.com/web/grfosweb.nsf...ag/UGRD-5AUGZP

[Brian_UK]

Looking for some help in understanding cavitation in water pumps from cause, effects and prevention.

Cause As Nike's link states, lack of sufficient head pressure at the pump suction will allow cavitation to occur.

The pump will develop a suction pressure that is not being satisfied by the amount of water available at the pump inlet due to the low NPSH (Net Positive Suction Head)

Effects When this happens the air (O²) in the water will come out of solution and implode on the pump impellor.

This action causes erosion of the impellor and eventual impellor failure.

Prevention Ensure that the NPSH is above the minimum required by the pump and as specified by the pump manufacturer.

Also, throttling the pump back can reduce cavitation but will, of course, reduce the pump flow as well.

[kevn]

Thanks for link Nike

So am I right in thinking cavitation wont happen in water chilled systems.

Got an interview next week and would really like to understand this some more.

Thanks

Kev

[Brian_UK]

It doesn't really matter what the water system is, if the pressures are wrong then it can happen.

[kevn]

This process occurs in regions inside of a pump where the pressure drops below the vapour pressure of the fluid (the vapour pressure of the fluid is the pressure at which a fluid begins to boil or vapourize)

This bit was causing some confusion. Sorted now.

Cheers appreciate the help.

[nike123]

It doesn't really matter what the water system is, if the pressures are wrong then it can happen.

I would say pressure and temperature!

[kevn]

I would say pressure and temperature!

Yeah thats how it clicked.

[kevn]

What the **** is this. Oh right theres the edit button