7 replies to this topic

[jrtailor09]

Dear All,

I am working on the hydraulic calculation of pump for one of the ongoing project.

My client has raise the query to consider pressure loss due to vortex breaker. Till now i haven't consider pressure drop due to vortex breaker for hydraulic calculation.

Any body has come across such kind of requiremet ?

Is there any stadard for the considering pressure drop for vortex breaker ?

Please help.

Regards,

Jatin

[ankur2061]

Jatin,

The link below could prove useful:

http://eng-tips.com/....cfm?qid=268143

Regards,
Ankur.

[jrtailor09]

Dear sir,

Thanks for your immediate response.

Actually i have a sufficient margin in NPSHA but while producing document we have to show something to client which is technically acceptable.

Regards,

Jatin

[ankur2061]

Jatin,

I don't think that it will be easy to find some kind of a generalized pressure drop or equivalent length formula for a vortex breaker. I would just take the exit loss from the vessel and provide a margin on it and this should suffice.

Regards,
Ankur.

[jrtailor09]

Ankur2061,

You are right. I will proceed accordingly.

Regards,

Jatin

[katmar]

The book "Handbook of Hydraulic Resistance" by Idelchik (JAICO Books) has a whole chapter on flow past grids, screens and gratings - but no mention that I could find of vortex breakers. You could probably estimate something from one of Idelchick's formulas in this chapter. However that would be overkill in my opinion.

If you have a safe margin on your NPSH I would be tempted to model the vortex breaker as a circular orifice with the same open area as the vortex breaker (i.e. the cross sectional area of the pipe less the area taken by the vortex breaker plates) and then double the pressure drop for safety. If this comes inside your NPSH calculation that should satisfy the client - or at least allow you to sleep at night knowing that you have a workable design.

[latexman]

I can think of two possible approaches. First, would be to treat the exit as a non-circular cross section and calculate hydraulic radius and equivalent diameter. This first method has considerable technical merit. Second, to base the exit loss velocity on (the nozzle area - the cross-sectional area of the vortex breaker within the projected area of the nozzle). This second method has less technical merit, in my opinion, but it does add margin based on a technically sound concept - velocity.

[jrtailor09]

Katmar / Latexman

Thanks a lot for your input aginst my query.

Katmar : I don't have "Handbook of Hydraulic Resistance" by Idelchik (JAICO Books). I have been using CRANE " Flow of fluids through valves ,fittings & pipes ".

Regards,

Jatin