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Duct Construction and Uses
Discussion in fabricating and use of products that move air including spiral pipe, duct board and typical sheet metal work.
       


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  #11  
Old 10-21-2008, 06:38 PM
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I don't see any advantage in using double (aerofoil) vanes over single vanes. Anyone?
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  #12  
Old 10-21-2008, 09:21 PM
device device is offline
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Originally Posted by Dad
I don't see any advantage in using double (aerofoil) vanes over single vanes. Anyone?
the aero foil (spelt wrong am sure ) type are used for higher pressure systems..
a single blade cannot stand the high air movement and buckles also the double bladed ones act like a airplane wing to decrease turbulance and get the air even smother..
they are also used in elbows where the depth of the elbow is just so large tht using a single just is not sturdy enough..
um.. thats bout all i can remember from school
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Old 10-22-2008, 06:39 PM
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device - you must have been an excellent student! Thanks for the info. All of my work is residential or light commercial. I think I'll stick to the single vanes (simple to fabricate with vanerail).
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Old 10-22-2008, 07:21 PM
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device - you must have been an excellent student! Thanks for the info. All of my work is residential or light commercial. I think I'll stick to the single vanes (simple to fabricate with vanerail).
heh thanks dad!
i was never one to mess with hvac too much when i was getting through my apprenticeship..my hours were spent @ a truck body manufacturing plant in edmonton..but i had to learn about hvac to get my ticket..the sheet metal certification emcompassed so many different aspects of metal forming that thats the only ticket there was for me @ the time.. in retrospect i am glad i trained ther..opened my eyes to other things than just the regular mainstream sheet metal that the general public thinks!
well you know Tinbasher!..i always corrected every one and said there was no tin bashing in our shop..they are all tinsmiths !
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  #15  
Old 11-17-2009, 04:27 PM
greenman9 greenman9 is offline
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Quote:
Originally Posted by Dad
I don't see any advantage in using double (aerofoil) vanes over single vanes. Anyone?
Another advantage of the double walled vanes is the differnce in the radius of the "heel" and "throat" of the vane, kind of like an air plane wing or propeller. kind of related check this out

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  #16  
Old 11-17-2009, 04:44 PM
cactassdupree cactassdupree is offline
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Yep double vanes for me. They work better and take a little longer to build. So we all come out ahead! Right? dupree
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  #17  
Old 11-23-2009, 08:11 PM
jw223 jw223 is offline
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I could be wrong here, so please correct me if I am. I was tought that the square heal or throat made more of a difference if the fitting was used on the supply or the return. Radius heel is more important on the supply, where a radius throat is more important on the return. This is assuming that neither fitting has vanes. I perfer the look of radius fittings, and just install full length vanes. Comments? I think those pics come out of Manual D.
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  #18  
Old 11-25-2009, 12:52 PM
sheetmental sheetmental is offline
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the other thing about double wall vanes is that air flowing over the top of the vane travels farther than the air over the bottom of the vane, like an airplane wing. on a wing, it creates a pressure and velocity difference between the area above the wing and below. i would suspect the same rule would apply inside the duct. my instinct tells me it would smooth out the flow by helping to pull the air through the vanes, and keep the velocity up at the same time, while eliminating the static pool that would normally be found in the corner of the square heel. it's just my theory though, i don't know if that's actually true.
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  #19  
Old 11-25-2009, 08:25 PM
rickey rickey is offline
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In my neck of the woods double vanes are preferred because of the time of fab., we use the duro-dyne, measure-cut-install and be done with it..The single vane you have another step in rolling the vane and in commercial installs being up against high pressure you dont go wrong with a double vane but the installers here in just this company I work for have this strange way of looking at vanes. That is they think the first vane closest to the square throat should be left out. Why? I dont know im hoping someone would settle this for me but they believe its a restriction having a vane close to the throat. Now this is just here in this shop, Im hoping to get some feedback here so I can show them this valueable info among the best around, fore finding the correct answer in some text book is long standing on a shelf in the some library. Personally I like radius ells / tees but the smacna has the 1.5 x thing going on and doing the single vane lets me spend allittle time with a fitting enjoying the art. Since joining a union the time factor sometimes takes some of the joys in some aspects of the trade.
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  #20  
Old 11-25-2009, 11:16 PM
tinmetal tinmetal is offline
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the max pressure velocity on elbow that doesnt need a vane is 1000 after that you need to put a vane on it...
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