Water flow - more through 45 elbows than 90 elbows?

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Here is a somewhat more esoteric question. I have to snake around some stuff, and I can do it with two 90 degree elbows, or two "45" degree elbows. In the end, will using the 45 elbows give noticably increased water flow? The pipe goes into a shower valve that is 1/2 inch, and the interior of the valve is even more restricted, so I'm thinking in this case it won't make any difference.
But out there in the real world where we bend this way and that way, does it matter how sharp the bend is wrt water volume?
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Don't worry about it.
But I can tell you're an obsessive type, so if you want, you can look up the equivalent friction loss of a 90 degree and 45 degree elbow with regard to pipe diameters in a fluid dynamics book at the library or on Google books if you don't believe me. From what I recall, neither is significant, and you won't notice a difference.
Worry about low-flow shower heads instead.
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I just happened to have it here: Reg 90 degree elbow = 0.92 to 3.6 feet of pipe (depending on joint type geom.) Reg 45 elbow = .45 to .71 feet of pipe (depending on joint geom.)
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wrote:

I am cursed with curiosity for just about everything... <ggg> what if...? what if ... ? what if ... ?
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wrote:

Proly not the biggest deal, but certainly two 45s are more elegant. Slightly more expensive than one 90, but certainly more correct. And the effect of pressure loss will be proportional to flow -- truly insignificant with a low-flo shower head, perhaps noticeable in something like a high-flo garden hose.. 90s in air conditioning have a pretty substantial effect, and 45s would be a good idea there.
--
EA



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wrote:

Personally, I always use a 45 degree elbow when I have a choice. For example to change directions and elevations at the same location, such as when a pipe is traveling parallel to and between joists and must make a 90 degree turn and drop below the joists, I always use the 45 to angle down to below the joist and then a 90 to turn across the bottom of the joist. If I am going around something such as another pipe where one would need 4 90s to get around the obstruction, I always use 4 45s to accomplish it, if the obstruction is only slight, I will try to use "street" 45s to accomplish the offset. To me it looks better, it does improve the water low and also reduces noise at a high water flow.
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wrote:

Ah, there is something I hadn't thought of. How much more likely are the pipes to hammer because of 90 degree elbows, versus 45? I would bet that 45's are quite unlikely to cause hammering problems. though two 45's in a row might hammer just the same as a 90. Just guessing - I'm way outside of my area of expertise here. I don't want to do plumbing long enough to actually get good at it :-P
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In wrote:

Not likely to make any difference, I don't think. Hammering is more the effect of quickly turning a faucet off quickly which lets the water's inertia try to move the whole pipe system and thus "hammers". If anything, 90 would improve it by adding some damping or slowing to the "hammer" action.
HTH,
Twayne
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Zootal wrote:

Talk about self-referential...
Have you ever wondered why you wonder about so much? It could take a lifetime to discover that answer.
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Zootal wrote:

To me I wouldn't worry about it. Do you sleep good in the night?
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Like a baby :-)
Better than a baby - my kids always woke up at all odd hours of the night. Maybe like a log would be a better analogy.
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Zootal wrote:

Oh, man, you're blessed. One of 3 important health indicator. The other two are eating well and eliminating well.
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I was pretty busy tonight, so I didn't get a chance for dinner until late. I had a bowel of cottage cheese, and another bowl with kimchi, kimchi radish, and a few slices of some summer sausage left over from Christmas. I can hear the EEEWWWs already....
I'll decline to comment on the third health indicator :-)
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.iad:

I feel for anyone sleeping with you :)
Harry K
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Zootal wrote:

Capture the result, it's a good form of alternative energy.
TDD
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Zootal wrote:

I once told this gal that she wouldn't want to sleep with me. She asked why not, I answered, because I sleep like a baby, I wake up crying every two hours and want to nurse.
TDD
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Per mike's research, it appears that 2 45 are so close to identical to 1 90 that....
In any case, the additional 'drag' on your flow will be so small as to not be noticeable unless system pressure is so low as to be considered a failure anyhow.
Harry K
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I studied this about 25 years ago, when I was taking some fire protection courses. The 45 are far less restrictive.
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Christopher A. Young
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You are aware that the OP is talking about elbows, and not wives, right?
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EA

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On Feb 10, 7:35pm, "Stormin Mormon"

They quote the flow restriction of the various fittings by the amount of equivalent pipe length they add. And while the 45s are individually about 5x less restrictive, you do need to then use two of them and the net effect in the given application isn't enough to make any noticeable difference. For example, a 1/2" 90deg elbow is equivalent to 3.6 feet of pipe. A 1/2" long radius 90 is equiv to 2.2 feet. A regular 45 elbow is .7 feet.
So, using two 45's, you get 1.4 feet versus 3.6 feet, saving equivalent to 2.2 feet of additional pipe run. If you used a long radius 90 elbow, you'd only be saving .8 feet of equiv pipe.
Those numbers were for screwed fittings, but similar effects are going to apply to copper as well.
http://www.engineeringtoolbox.com/resistance-equivalent-length-d_192.html
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