Plumbing question

[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

[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 Mr OM

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?

[mark]

As said big is better for pipe runs and loss due fittings, why I stayed with 1.5" to the bottom of my display.

What I wish for is a calculator that would take into account various line sizes (I'm running a 1.5" return line from the pump but then reduce to 1" at the display bulkhead).

[golf nut]

Hard to believe isn't it, but it is true.

[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.

[golf nut]

Originally Posted by Myka

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.

I think the pump comes into play here, I agree with what you can do to cut my toes off (God forbid) but you are using a positive displacement pump that doesn't know the meaning of the word backpressure, a typical aquarium pump doesn't come close to 3 psi and simply doesn't do what a hydraulic pump is capable of, in effect you are both right.

[sphelps]

Originally Posted by Myka

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.

Adding a nozzle will increase dynamic pressure within the nozzle and increase the head pressure on the pump, but this will result in less flow on a centrifugal pump. In addition as stated positive displacement pumps are not effected by head pressure, they pump the same amount of fluid no matter what. Of course they do have a maximum operating pressure before something blows up which is why such pumps will have a release valve for safety.

You can't relate such systems to aquariums, we use centrifugal style pumps where head pressure is relevant, I'm actually pretty confused on what you argument is at this point

[Myka]

Originally Posted by sphelps

I'm actually pretty confused on what you argument is at this point

LMAO!!!

I give up on you, you aren't understanding.

[banditpowdercoat]

Originally Posted by Myka

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.

But were not changing the pump. What would your 1200PSI pump out out with a open 4" hose, No nozzle. I guarantee you it wont be 1200PSI. But it still woould take your toes and whole feet off if it was exiting the hose at 1200PSI

I'm not acctually sure where this is going anymore, but head pressure is irrelavent of the volume, its height. Thats the main reason why our tank glass gets thicker the higher the tank gets. Higher water, more pressure. Regardless of vessel size. Just like pressure in the Ocean at 15ft below, is the same as in a pool at 15' below. Head pressure has nothing to do with flow or anything. Its just the weight of a column of water.