Water flow - more through 45 elbows than 90 elbows?

Feb 11, 2010 32 Replies

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?


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.

I just happened to have it here: Reg 90 degree elbow =3D 0.92 to 3.6 feet of pipe (depending on joint type geom.) Reg 45 elbow =3D .45 to .71 feet of pipe (depending on joint geom.)

I studied this about 25 years ago, when I was taking some fire protection courses. The 45 are far less restrictive.

You are aware that the OP is talking about elbows, and not wives, right?

mike wrote in news: snipped-for-privacy@b7g2000pro.googlegroups.com:

I am cursed with curiosity for just about everything... what if...? what if ... ? what if ... ?

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.

The more bend, the more velocity loss which is perceived as low pressure when a faucet is open. It is beneficial to minimize the amount of bends in a run of pipe. If a large number can not be avoided, stepping up to the next larger pipe size will help compensate for the restrictions.

Talk about self-referential...

Have you ever wondered why you wonder about so much? It could take a lifetime to discover that answer.

I just built a shower with 1/2" copper. It feeds 3 shower heads. If I had to do it again, I would feed it with 3/4" to the valve. It is OK but the pressure could be better. If you turn off one of them, the other two are better. My shower valve is a 1/2" feed too with a small opening inside the valve. I thought that using the bathtub feed which is larger would compensate as it is larger than the shower outlet in the top of the valve, but it is still lacking on volume and pressure.

R

--- news://freenews.netfront.net/ - complaints: snipped-for-privacy@netfront.net ---

Common sense would be that two 45s are better than two 90s. But if they area only to feed a shower head, I don't think even the pickiest person would be able to tell the difference.

Hi, To me I wouldn't worry about it. Do you sleep good in the night?

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.

Hi, Oh, man, you're blessed. One of 3 important health indicator. The other two are eating well and eliminating well.

Tony Hwang wrote in news:guLcn.90661$ snipped-for-privacy@newsfe16.iad:

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 :-)

snipped-for-privacy@b7g2000pro.googlegroups.com:

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

.iad:

I feel for anyone sleeping with you :)

Harry K

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

Capture the result, it's a good form of alternative energy.

TDD

Use flex pipe if you want to snake.

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