Passive flow through capacity of various Bulk Head size fittings?

[Tobe1971]

Anyone have a formula?

 I am positioning my 40 gallon Refugium next to and just above a 75 gallon that I'll be using as a frag tank. I'm drilling a hole in the side wall of the Refugium to gravity feed the Frag tank next to and below it.

Does anyone know or know how to calculate the passive flow rates of various diameter bulk head fittings?

(The Refugium will be fed from section one of my primary sump below my display tank in an adjacent room. The Frag tank will have a Life Reef Overflow to return water to section 2 the primary sump)


Thanks!

PS I've attached a quick couple of sketches to give a better picture of what I'm planning...

 Toby

[Tobe1971]

this is a more complete second sketch...

[discus513]

I have heard that a standard 1'' bulkhead gets around 600gph with a standpipe, Im not sure about how to calculate it just going off of hear say

[Gary]

Calculation is not difficult if you have volumetric flow rate and fuild velocity. You can determine volumetric flow rate from the pump size (lift height, pipe size, etc.). The velocity is dependent on pipe diameter, length, type of flow ( laminar, turbulent), drop, etc. Filling all the blanks in is the problem. There is some emperical data around that maybe more useful and easier.
Gary

[muttley000]

http://www.wetwebmedia.com/BulkheadFloRateArt.htm Great article on the subject

http://www.wetwebmedia.com/SystemPIX/PlumbingPix/Oneinchart.htm  Why not to count on a 1" bulkhead for more than 300 GPH safely

[Gary]

Those are good articles. In the tables, at some point the siphoning will begin to occur. Here is another site for gravity return pipes. It is in pounds per hour (need to divide by 8.34 pounds/gallon).

http://www.engineeringtoolbox.com/gravity-condensate-return-capacity-d_479.html

[Tobe1971]

Thanks for the replies!

[discus513]

Wow 350gph is a lot lower than I expected and also a lot less than what tank manufactures call out there overflows will handle. This marinland corner flow says it can handle up to 700gph and I am pretty sure they come standard with 1" bulkheads: http://www.marineland.com/Products/glass-aquariums-and-tanks/corner-flo-pre-drilled-aquariums.aspx