Plumbing question

[Reefer Rob]

Originally Posted by Myka

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.

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 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.

[Myka]

Originally Posted by Reefer Rob

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 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.

Maybe I'm not being clear about what I mean, or maybe you're wrong.

We use say 1200 psi to go through a 5/8" hose then through a 1/8" fitting on the end (we use this on Hydro-Vac trucks to cut the ground), and voila! It will cut your toes off. If we use 1200 psi pumped through a 3" hose (which you would never be able to hang onto, and you'd need a muuuuuuuch bigger pump to get 1200 psi out the end of a 3" hose), and you wouldn't hurt your toes with it.

So...slap your fancy words (pressure, head pressure, velocity, psi, flow, whateeeever) on that equation, and tell me what the heck you mean that I am wrong.

[sphelps]

Originally Posted by Myka

I didn't say more pressure increases flow! Where do you see that?

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

Originally Posted by oilfieldsafety

but by going to a larger diameter pipe won't you increase your head pressure due to weight of the water column and in fact decrease your flow?

[kari]

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

[banditpowdercoat]

Originally Posted by kari

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

Bernoulli, LMAO. Were not building plane wings here

[golf nut]

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?

[sphelps]

Originally Posted by banditpowdercoat

Bernoulli, LMAO. Were not building plane wings here

Bernoulli's equation can be used in all kinds of fluid mechanics, including pipe flow.

[sphelps]

Originally Posted by kari

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

haha, only as a last resort

[hillegom]

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.