Explain bulkhead size to pvc and other fittings

[Jankees]

For a 90gal FO 860gal pump what size, how many, and size fittings. I was told 2", 1 3/4", 0ne 1" will do just fine. The problem that I have is snail blocking U tube, and the overflo can't handle full pressure of the pump. Someone was selling me 1" bulkhead, L pvc. and screen for $7.

[ADS]

1" should be fine on a 90g. 2" is unecessary. The hole for a 1" bulkhead will be 1 3/4-2" depending on bulkhead manufacturer.
Aquaticecosystems has nice charts for sizing.
Adam

[skearse]

Warning-"Dork" engineer response attached-read with caution!!

FWIW, this is the sort of stuff I do every day for my job (piping design, pump curves, etc. ) If you want to, get me the pump model, approximate height of the return line (from the pump to the tank), and I can get you a pretty good idea of the flow you could expect and the line sizing.

As a rule of thumb, you'll want to keep the velocity of the water moving between 1 and 5 ft per second, probably around 2-3 ft/sec-this gives you good flow without a lot of discharge pressure. For schedule 40 PVC, and 860 gallons (per hour, I assume, on the pump), the velocities at the different pipe sizes are about:

2" PVC: 1.37 ft/sec
1-1/2" PVC: 2.26 ft/sec
1-1/4" PVC: 3.08 ft/sec
1" PVC: 5.32 ft/sec

Based on this, you'd be OK with 1", 1-1/4", or 1-1/2". If the pump is rated for 860 gph @ 0' of head, you will not be getting this flowrate-you will have some head pressure develop if you are pumping the water up to the tank. (With the pump model type and height I can pull a pump curve & tell you a little more accurately what the flow would be). With 4' of head (height of tank & stand, and some friction in the pipe), you'll probably end up closer to 550-600 gpm. Then, the velocity in the 1" pipe comes closer to 3.7 ft/sec.

All of this, to tell you that I agree with Adam-you should be fine with 1" pipe.

[Tomzpc]

See! I told all of you guys that Stacy was good for "something"!

[nine9d]

LOL, I hear he can build a mean sump too.

[skearse]

OK, so Tom & Ross get the 'special' treats at the meeting...