Bathtup-type vortex 2

[JStephen]

If you have a pipe drawing fluid from a reservoir, there is a possibility that a vortex can form, allowing air to enter the pipe, even though the pipe entrance is fully below the fluid surface. Example: A bathtub draining. Question: Does anyone have any information on minimum depth or maximum flow rates required to avoid this?

I'm familiar with anti-vortex plates and diffusers intended to prevent this, but have never seen any actual test or theoretical data to show that they would work.

Thanks!

 

[CanuckMiner]

JStephen,

Goulds Pump Manual has a section on suction pipe design. The following link should take you to an excerpt of the manual that illustrates recommended pipe submergence.

http://www.gouldspumps.com/pag_0006.html

Cheers,
CanuckMiner

 

[quark]

In case of pumping water, you can use the following equation for the minimum submergence.

S = D+[(0.574Q)/D^1.5]

Where S is the submergence in inches
D is suction pipe diameter in inches
and Q is flowrate in USGPM.

 

[JStephen]

Canuck, that looks like some very useful information. Thanks.

Quark, do you have a reference or source for that equation? Thanks.

 

[quark]

ANSI/HI 9.8 – 1998, Section 9.8.7 (I actually picked this one from Thread407-19111

Also visit

http://www.fluidedesign.com/help11.html