What happen if I had this sittuation in this system?

[Anderson Oliveira]

Hi from Brazil.

Firstly, sorry if the english it's not good.

I attached a pic to help me explain the situation.

Well, I've got a pumping system in which there are two branches in suction branch. Those branches are vertical and opened to atmosphere.

The pump is 4 meters down from branches and the opening.

Here is my doubt: If my pump is a centrifugal one, cavitation can happens from air entrance in those branches?

my e-mail: anderson.albuquerque@mdiasbranco.com.br

 

[EdStainless]

A list o f what is wrong;
These two lines will limit the head at the pump inlet which is not good
They will also assure some air entrapment in the flow, which is not good either
Are the numbers the pipe sizes? if so then your pump suction side is undersized, which is not good

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[bimr]

According to your sketch, it appears that water would drain out of the tank and exit the suction branches.

If the suctions branches are higher than the level in the tank, you would encounter air entrainment, not cavitation. You may also encounter some air binding as well.

The amount of air entrainment will depend on the relative heights, pipe diameters, and pumped flow rate, none of which you mention.

Air Entrainment

 

[LittleInch]

What a strange system.

Your sketch would be much better with some elevations and lengths of the various piping

Assuming that the top of the pipes is higher than the level in your tank ( otherwise as bimr says all your water will just flow out the open hole), then it depends on whether the head of the water tank is greater than the friction head losses in the pipework. up to the tee where the pump inlet goes off.

If it is then you shouldn't have any air entrainment as there will always be water in the braches above the tee. However it depends on how much water is present in the vertical branches when the pump is running. If its less than about 100mm, then you're likely to get some occasional gulps of air in the system, especially at start-up.

Always 100mm or more, even during the transient at start-up then you should be OK.

A bit more data would help.

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