The one where CW and GBBUDD argue about pipe sizing.

[combatwombat]

According to the charts you must have at least a 4" pipe to flow 11000 gph @ ~5ft/s. But if we increase the flow velocity to 34 ft/s it will happily move 11000 gph through a 1.5" pipe. It's all relative: flow rate- flow velocity- pipe size- head - and pressure. All those must be taken into account.

But of course…

 

[DanielleB]

Well I was planning to put 2 in everywhere in the event of upsizing later but now I'm thinking I need to go to 3. LOL.

 

[combatwombat]

Well I was planning to put 2 in everywhere in the event of upsizing later but now I'm thinking I need to go to 3. LOL.

If you're doing 5,000 gph+ through a single line or long runs (or both), then you may benefit from 3" as it will significantly reduce your dynamic head. But if I remember right, you have a very short run from intake bay to bog.

 

[DanielleB]

I do plan to have a very short run so probably wont be an issue in my case. However I did see this clip where John Adams from modern design aquascaping says that upsizing will increase your pumps efficiency even when the outlet is smaller than your piping.

 

[combatwombat]

I do plan to have a very short run so probably wont be an issue in my case. However I did see this clip where John Adams from modern design aquascaping says that upsizing will increase your pumps efficiency even when the outlet is smaller than your piping.

Right on. Engineers designing pump systems don’t pay any attention to the size of the outlet on the pump. They design to a pipe size for a specific flow rate.

Larger pipe will reduce dynamic head, allowing more GPH at the end of the pipe than a smaller. But pumps actually use more power as you exert less head on them. You’ll notice when reviewing pumps that some report power at max flow and at max head. And max flow is always way higher.

So in terms of efficiency, it’s kind of 6 of one, half dozen or another.

 

[netvine]

hey folks, Im studying up on my head calc charts and wondering, why do male female adapters cause so much head loss? equivalent of 4.5 ft of head on a 2" pipe. Makes me wonder If I should stick to using slip/slip bulkheads rather than fpt.

 

[combatwombat]

hey folks, Im studying up on my head calc charts and wondering, why do male female adapters cause so much head loss? equivalent of 4.5 ft of head on a 2" pipe. Makes me wonder If I should stick to using slip/slip bulkheads rather than fpt.

I think you're misinterpreting the charts. a 2" adapter adds the equivalent of 4.5' of 2" pipe not 4.5' of head. The 4.5' of pipe will equate to different amounts of head pressure depending on flow rate. For instance, at 5,000 gph, a male female adapter = 4.5' of pipe = about 0.5' of additional head.

If you're pumping at a different flow rate, the amount of added head will be different, but a 2" male/female adapter will always add the equivalent of 4.5' of 2" pipe

PVC Pipes - Equivalent Length and Pressure Loss in Fittings

Minor loss in PVC and CPVC fittings expressed as equivalent length of straight pipe.

www.engineeringtoolbox.com