Looking for COTS or Surplus U-Bend Fittings

Hello
I am looking for u-bend fittings with a round or square cross section. It's for a heat-exchanger design ... COST-SENSITIVE. I have put up images, Solidworks generated, of either fitting at -
http://www.geocities.com/wwswimming/ubendround.jpg
http://www.geocities.com/wwswimming/ubendsq.jpg
the first prototype used 3/4" square tubing. In the images linked to here, center to center distance, between the 2 apertures of the U-bend, is nominally 4 inches/ 10 centimeters.
But that's very nominally - the design is fluid at this stage. I really do not want to use custom fabbed parts for the U-bend transition, at least not for prototypes & LRIP, low rate initial production.
Material - aluminum, copper, brass, plastic, rubber.
I did a web search for this and am swimming in data for right-angle transitions. But to get a U-bend out of 2 swept right-angles, I might need to add a third piece, which increases part count.
Thanks.
I heard about a guy in Arizona with 20 dishwashers in his multi-acre backyard. I'm hoping there's a surplus or plumbing vendor with these kind of parts in quantity.
Roger
wwswimming at yahoo.com

how about using two standard 90 degree long elbows? Mcmaster sells them from stock for a couple dollars each
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hi michael
thank you for the suggestion.
the design will have 20-60 U-bends. i may end up constructing it from "long elbows" <== i think i just learned a new tech. term !
but, if the U-bends were "out there" and available off the shelf, well, it's worth looking, i figure.
Roger

snipped-for-privacy@yahoo.com says...
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Try also - wrot copper return - for example, at the bottom of this page... http://www.nibco.com/cms.do?id=2&pIdH
Don't ax me why wrought is spelled "wrot" when referring to copper fittings.
Ned Simmons

You may have more success using '180 return' as your search term or calling local pipe/tube supply houses.
Don't know a thing about this vendor, but here's a copper tube 180 return sweat fitting: http://www.rparts.com/Catalog/Installation_Components/fittings/copper_t&f.asp (about 1/3 down the page).
Lance *****
snipped-for-privacy@yahoo.com thought carefully and wrote on 12/7/2005 9:06 AM:
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Thanks for the help - "180 return" it is. Looks like there are some that are real close to what I need .
Roger

A couple of ways to fab what you want. 1) For the round tubing, a hydraulic tube bender. You can get 'em at Northern Tool or Harbor Freight for cheap, but they only bend 90 degrees. If you'll look at the design of them, though, you could probably put together a jig which would work for 180 degree bends by using using a cheap hydraulic car jack, some plates and a specially machined forming tool similar to the ones used with the off-the-shelf benders. 2) For the square tubing, laser or water-jet cut top and bottom profiles welded to thin strips which are bent to conform to the inside and outside diameters.
Some steel suppliers will bend your tubes for you, either square or round, within some limits. You still have to weld on the reduced size ends, but that should be no big.
Mark 'Sporky' Stapleton Watermark Design, LLC www.h2omarkdesign.com
snipped-for-privacy@yahoo.com wrote:
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thank you, sporkman & everybody else !
sporkman, it looks like you use Solidworks. I bought it about a year ago & I like it.
I also bought Pro-E. I don't like it yet.
Regards,
Roger
http://www.wwswimming.com /