Cavitation....

[Eric'n'Ernie]

I've got a shower pump, plumbed it in, wired it up and all is well and working fine.
However, before I happily tile up the shower cubicle I have a nagging worry I need to sort out.

The shower mixer MI's say that if the pump has non-return valves I should remove the non-return valves from the mixer "to avoid cavitation".

I can't work out if the pump I have has got non-return valves or not, so while I try to work that out, I thought I'd ask on here to see if any of you good people can tell me :

1) What is cavitation?
2) Do I need to worry about it?

 

[hi-spec plumbing heating]

with out going into detail cavitation is do with air.
yes it does matter.
what pump and model have you?

 

[Eric'n'Ernie]

It's an Altech "Shower Booster Pump 50".

 

[Eric'n'Ernie]

...twin impeller, 1.5 bar max variable speed pump, £129 from Grahams.

 

[Eric'n'Ernie]

Scrub this query - I found out from th e manufacturer that the pump doesn't have non-return valves.

See new topic for next installment.

 

[chrishutt]

with out going into detail cavitation is do with air.

No, it's nothing to do with air. It's to do with vapourisation of the fluid being pumped (in this case water) at the pump impeller due to a low static pressure combining with further pressure drop due to high pipework resistance (e.g. from NRVs).

 

[hi-spec plumbing heating]

with out going into detail cavitation is do with air.

No, it's nothing to do with air. It's to do with vapourisation of the fluid being pumped (in this case water) at the pump impeller due to a low static pressure combining with further pressure drop due to high pipework resistance (e.g. from NRVs).

.

Cavitation is a general term used to describe the behavior of voids or bubbles in a liquid. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Such cavitation often occurs in pumps, propellers, impellers, and in the vascular tissues of plants. Non-inertial cavitation is the process where a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths and can also be observed in pumps, propellers etc.

 

[chrishutt]

Congratulations on your cut and paste job from Wikipedia, hi-spec. It is normal to give an acknowledgement when you copy things from another author.

Unfortunately for you it says nothing to support your assertion that cavitation is to do with air. The voids or bubbles referred to are full of vapour (i.e. steam when water is being pumped), not air.

 

[bengasman]

And I though it was what you get if you don’t brush your teeth

 

[ChrisR]

You only get it if the waters above about 60 degrees.

(makes your gums go pink, that)