I agree with you.....but that is something different ......your putting the same volume through a smaller pipe....which increases pressure...

I thought we were just talking about head pressure ???????

[quote=Myka;400466]A person will get less gph, but more psi at the end of a 1" pipe than using the same pump on a 3" pipe.
QUOTE]

Put a pressure gauge at the end of each pipe and it will be the same.

I can see where I got screwed up. The volume increases in the larger pipe. and pump only displaces a certian amount of water. Ya the larger pipe will not add anything to head pressure. Like the difference in a drain. Take a 40g tank, and a 140g tank, both of same height. Drill a 1" hole and install a bulkhead in it. Think of the tank as the larger pipe. more volume, right. Which would have more pressure at the 1" bulkhead? Neither

I was kinda thinking backwards in my previous post. It doesnt matter how large the pipe is, the pump is only pushing put it's amount of water, regardless. When working on gravity, water falling down a pipe, then the PSI gains as the pipe narrows due to the velocity of the water, not just head pressure.. Principal behind Hydraulic strip mining

Well you started off your post by saying you agreed with the fact that larger diameter pipe means more water weight and therefore less flow. Your next statement seemed to be your argument on why you agreed. Sorry for the confusion but I'm not a mind reader :biggrin:

You guys should listen to Sphelps on this matter or he may just go Bernoulli on you.

No it won't be. The pump will be restricted by the decreased flow out of the end of the pipe...the same reason fittings on a pipe decrease pressure. Now, if you close the end of the pipe you would be right.

Bernoulli, LMAO. Were not building plane wings here :lol:

I think you're getting confused. Decreasing the pipe diameter will increase back pressure at the pump, but I don't think you can use it to increase PSI at the outlet that way. Think of the applications for that kind of technology :wink: Perhaps you're thinking of velocity? I'm not sure what that has to do with head pressure though, which is influenced by gravity, not a pump.

If we take a 5" pipe and adapt it to a 3/4 opening in the pump, the weight of the water in the pump is only the area of the 3/4" opening times the weight of water. The rest of the weight, 4.5" will exert force on the adapter.
As sphelps says, use the calculater in the link above, as the pipe dia. increases, head pressure goes down.

So that we are are clear on this question, if the pump on the left has reached its maximum head, it would be the same height as the pump on the right with a much larger diameter?