Plumbing ? Are 2 45s better than 1 90

[Liquid Hobby]

I try to stay away from 90 elbows whenever possible, however, I do need some... So, is it better to put 2 45s together to get to 90? Would there be less flow disturbance this way?

[abwcandy]

I've thought about this in the past and I would think two 45s are better. Even better though would be to get some curved electrical PVC conduit. They have nice 90 degree curved sections. 3/4" pipe has about a 6 inch radius and one end is flanged so that eliminates one of your connector pieces.
However that large radius will require more careful planning of the pipe routing if space is tight. Well worth it IMO

[Pickupman66]

yes, you will get much less restriction with 2x 45 than a single 90.

[abwcandy]

Really, anything you do to lessen the sharpness of the turn will lessen restriction. Just think of taking a curve in your car. You can take a gradual curve much faster than a sharp curve. Same idea.

[PurdueWaterGuy]

Unfortunately most PVC 45 degree ells have about 1/2 the resistance as a 90 degree, so you typically don't gain anything, flow-wise. Some manufacturers make "sweeping" ells, that have a larger radius for just this sort of situation. As you might guess, they are low-volume items, so the price is higher....

Not to endorse them, but the Ryan Herco catalog has all sorts of tables for PVC pipe data. At least the paper version does, I can never find what I am looking for on their web site.

[Stroob]

According to the head loss calculator on the main page it is better for 1 90 than 2 45s.

[nixer]

http://www.engineeringtoolbox.com/pvc-pipes-equivalent-length-fittings-d_801.html

[Liquid Hobby]

http://www.engineeringtoolbox.com/pvc-pipes-equivalent-length-fittings-d_801.html

Interesting. If I'm reading that chart correctly, a 1" 90 has a friction loss of 2.5 where a 45 has a loss of 1.4. So, putting 2 45s together creates more friction loss! That's counter intuitive.

This is for a closed loop outlet line, so no electrical grade curves... I like the plumbing to be overbuilt!

[GlassReef]

I can verify the conclusion that is being reached here. A 90 is better than two 45s. When I was building my system, an engineer, that works with this kind of thing PMed me and advised me of the fact. Who woulda thought?

[nixer]

I can verify the conclusion that is being reached here. A 90 is better than two 45s. When I was building my system, an engineer, that works with this kind of thing PMed me and advised me of the fact. Who woulda thought?

also 2- 1" pipes are not better than one 2"

you gotta watch those engineers also many dont know dirt!