The weight of water in motion?

RickDelta

Hello HeatingHelp.com community!

Question: A water pump (with a foot check valve) has a 3" dia. x 12 foot height vertical discharge immediately attached to the pump casing.

The weight of the water not moving (just resting in the pipe) is around 4.5 psi.

What's the weight of the water exerting down on the pump within this vertical pipe when the pump is moving water thru it?

I'm assuming the same 4.5 psi

Larry Weingarten

Hi, I think there are two different things at play here. One is the weight, which is a constant. The other is inertia, which will have a variable effect, depending on speed. But to try and answer your question, the weight won't change with water's motion or lack of motion.

Yours, Larry

Jamie Hall

You are confusing weight and pressure. And, as @Larry Weingarten implied, there are momentum and Bernoulli effects, among others, at play as well.

The weight of the water in that pipe is around 40 pounds, assuming that it is full. That is a constant. The pressure -- could be all over the place depending on flow conditions.

leonz

The weight of water in a 3 inch pipe 12 feet long is 32.4 pounds+-

PSIG@ the bottom of a 3 inch pipe 12 feet high = 12*.434 @ 39 degrees Fahrenheit=5.208 PSIG

leonz

You should look at how Hale and Waterous fire pumps are constructed with their impellers to learn more about how they pull water out of temporary transfer water pools and creeks below road level.