Does anyone actually calculate friction loss in the pipes?

[Garrik]

I am doing a bunch of design work around some Aquascape PL series pumps. I was sailing along happy that my "application head" was basically zero, until I realized that pipe and fitting friction loss was a thing, and that I needed to do some math (or find a calculator on the internet, which is what I actually did of course).

Turns out that the friction loss in 100' of 2" PVC pipe creates the equivalent of about 22' of head if you try to move 7,000 GPH through it. And that is without any fittings - each T (in flow/branch config, ie input at the center) costs another 2' of head or so. Yikes!

The PL-9 7000 that I thought was going to deliver around 7,000 GPH at zero head will only deliver 4,100 GPH into 25' of head...

Am I missing something here? Does anyone take pipe friction loss into account when designing ponds? Does anyone use 3" or 4" pipe to minimize friction loss (I only ever see 2" pipe in videos...)?

Thanks!

 

[Lisak1]

This sounds vaguely like math. so I'll stay out of that discussion. I did just hear Ed from Aquascape discussing this on a recent video though. He did recommend oversizing your pipe to reduce friction.

For what it's worth, we used 3" on our pond. It's a bit harder to work with but if my husband had known about 4" I have no doubt we would have used that.

 

[Ronfire]

I used the calculator for mine and found it very help full and I think was accurate. The corners will make a big loss, If you can use the sweeping elbows or 2- 45 instead of a 90 helps.

 

[Dowscanner]

Yes it is important to figure head loss through the system. There are some good online calculators that make this relatively easy. I was able to eliminate 3" pipe and fittings by running two 2" . I ran a 2" suction run from bottom intake and another one from skimmer combining them just before pump strainer. Discharge line was also split immediately after leaving pump. Ran 2" to bog and another 2" to fountain and jets. Otherwise both of these calc'd out to 3" pipe. I would suggest setting pump strainer and pond at same level. That way pump self primes and water does not overflow when strainer is being cleaned. Also, locate the bottom suction inlet so it is easy to clean.

 

[Garrik]

Yes it is important to figure head loss through the system. There are some good online calculators that make this relatively easy. I was able to eliminate 3" pipe and fittings by running two 2" . I ran a 2" suction run from bottom intake and another one from skimmer combining them just before pump strainer. Discharge line was also split immediately after leaving pump. Ran 2" to bog and another 2" to fountain and jets. Otherwise both of these calc'd out to 3" pipe. I would suggest setting pump strainer and pond at same level. That way pump self primes and water does not overflow when strainer is being cleaned. Also, locate the bottom suction inlet so it is easy to clean.

Great suggestions - Thanks! I have found the calculator and am doing the math!