Plumbing question

[banditpowdercoat]

Originally Posted by Myka

Ooooooh but that was my point!!! If it's 1200 psi out of a 1/8" nozzle, it ain't gonna be 1200 psi out of a 4" tube.

OH. LOL I had to many beers last night

[banditpowdercoat]

But back to the basic question. Does head pressure change at the pump, when using larger diameter pipes for tank return.

NO, it remains the same. The pressure the pump see's is equivalent to the weight of water equaling the volume of a pipe the same diameter as the pump outlet, times the head height.

Now as far as friction losses, they are regardless of head height. Friction losses will happen on horizontal runs as well as vertical. If said pump was loosing flow (GPH) due to frictional losses, then yes, upping pipe size can gain back some lost GPH.

Heres a chart comparing firehose sizes and friction losses per 100' of hose. Distance and flow determine friction losses, not head height



Losses in PSI of firehose per GPM flow @ 100 PSI pump pressure

1.5" diameter
GPM/ PSI Loss

50 6.3
100 25
150 56.3

2" diameter

50 1.7
100 6.6
150 14.8
200 26.3
250 41.1
300 59.2

2.5" diameter

150 4.9
200 8.7
250 13.5
300 19.5

And for elevation, add 0.5 PSI for each foot

[Myka]

Here I thought the original question was well answered already, and that we were delving off further into the topic...???

[banditpowdercoat]

lol, I'll shut up now

[golf nut]

BTW there is no head loss in a closed loop

[sphelps]

Originally Posted by Mr OM

BTW there is no head loss in a closed loop

You mean there is no head loss from a result of height difference but there are still losses resulting from fiction and restrictions which add to head pressure. Power heads on the other hand could be assumed to have zero head loss.

[sphelps]

Originally Posted by Myka

Here I thought the original question was well answered already, and that we were delving off further into the topic...???

What tends to happen when people figure out they're wrong is they go on and on about something completely irrelevant as a means to justify their original statement. We can't always be right so when we're not we should just cut the BS and admit it

[brizzo]

I've found this thread insightful and helped me understand concepts I was completely ignorant of. Mostly the concept of how water height effects head loss, and how water volume does not. My thought process before was more water volume = more weight = more headloss. But it's only water height that does...

Thanks guys

[BC564]

Isnt it awesome when you go through 5 pages of the same answer as the first page?

[BC564]

oh....and that 27.2" of water colum equals 1 psi.....that is based on fresh water with a specific gravity of 1.....not the approx. 1.25 of our aquariums