Manifold Head Loss

[ohioreef]

How does a manifold affect flow loss? How do I figure that?

For ex: if I have 1000gph at the entrance to the manifold, how do I figure loss? Do I just add in the 90 bends and exits of the manifold into the head loss calculator here? Seems to me that would calculate a fairly large loss.

If I have 1.25" plumbing from the pump should the manifold also be 1.25"?

[KevinM]

Actually, to decrease your loss through the manifold, I'd make it out of 2". In fact, change to 2" right out of the pump, and don't decrease it to 1.25" until you leave the manifold.

Kev

[ohioreef]

Not sure I understand. I was thinking of ending with a closed loop manifold. I need to figure the head loss from the manifold to try to figure what size pump I need.

[dwdenny]

http://www.reefcentral.com/calc/hlc2.php here try this on the main page.

[RustySnail]

Flow restrictions on the intake side of a pump are more costly in terms of "head loss" than on the exit side. The pumps we use are not designed to generate vacuum; and flow resrtiction on the intake will cause lower pressure at the pump. If the pressure is too low, the pump impeller will cavitate. A few bends in the pipe and a short distance of standard sized pipe will not cause much restriction. Oversize the pipe from 3/4" (if that's the pump fitting size) to 1" and you should have little to worry about in terms of head/flow loss.

Also, if you are plumbing it as a closed loop, there is no vertical head loss. This is only included if you are pumping from a sump reservoir up to the tank surface. There is no "drain-back" on a closed loop, and as such there is no vertical height to account for. The net length of pipe you enter should be in the 'horizontal' column on the head loss calculator.

[ohioreef]

Thanks for the info!! I am pumping from the sump up to the tank. I was planning on putting the manifold on my return line.