Vortex

[hatanaka]

Pls, does anyone has a methode for determination of the required minimum static head above a exit pipe in order to avoid a vortex? The use of vortex breaker is unavailable.
The fluid is hot water (240 Celsius)
Thanks.

 

[friartuck]

If water acts the same as smoke, then the effect will also depend on the size of the hole. I can't help you any more than that.

PS
a.Why can't you use a vortex breaker?
b.Whats wrong with having a vortex?
c.Is the outlet an overflow? or a feed pipe.

Can you fit a grid on the inlet to the outlet to increase the outlet area. or have a large outlet which reduces.


Friar Tuck of Sherwood

 

[25362]

I don't have supporting evidence.

However, as told by colleagues, ROT's for minimum static heads of liquid to avoid vortex formation at the bottom outlet would be:

One source: 2 ft of head for every fps of velocity in the outlet nozzle when the level is kept constant.

Another source (probably the "safest"): a minimum of 15 ft, in particular if the level is falling.

One last source: the above minimum levels should be increased by an undefined amount if the liquid enters the vessel tangentially.

Friartuck comments and questions are highly logical and it would be advisable you consider them and revert.

At the end, economics, or even safety reasons, may dictate the installation of vortex breakers to reduce the liquid hold up and the concomitant large dimensions of the vessel.

Good luck.

 

[rmw]

I, too, do not have a definative answer to give you, but, if you were pumping this fluid with a vertical pump in a sump, then the pump MFG would dictate certain minimum submergence depths to you to prevent vortex formation in the sump. These might well be useful to you as a guideline.

Lots of pump sites to go to for vertical pumps. Try a site search on this site first.

It would be interesting to see how those values, the minimum submergence of the pumps correlated to the values 23562 gave you above.

rmw

 

[unclesyd]

Depending on what problems the vortex is causing downstream the following or similar device might work. We used this type device and others on pump inlets and the like.

http://www.vortab.com/Index.htm

Also if you have an outlet flange you can buy or make one that insert in the pipe from the out side. If you go this way make sure it is heavy enough.

 

[quark]

Perhaps my post in this thread378-78114 and a link of a preceeding post will be of help to you. No harm in trying.

Regards,

 

[tkdhwjd]

If you are in doubt, I suggest installing a low pressure drop vortex breaker. You may also want to check the liquid superficial downward velocity. I don't think many research works have been done (or I just have not heard any) on this topic. But I remember reading some research papers that if the velocity exceeds certain limit, excessive vortexing would result even in presence of a breaker.