Magnet Myths and Misconceptions

[tinman]

You have chasen an arbitrary location for your pressure zero.  The pressure falls from the pump outlet all the way back to the pump inlet.  Were the pressure actually zero at the middle of the upper pipe segment, there would not be any impetus for water to continue to flow past that point.

Looks like we have stumbled onto a subject that you know little about Mark. You do kknow what a jet pump is!dont you?!
Lucky for me,i have been working on pumping systems for over 25 years on mine sites,and knowing this sort of information was a must and part of our training.

The pressure and vacuum reach equilibrium exactly where i have depicted the pressure gauge(minus a very small amount due to friction within the pipes) that reads zero when all pipe sizes are equal in size and length,and a jet pump is used-as i also depicted.

Quote: Were the pressure actually zero at the middle of the upper pipe segment, there would not be any impetus for water to continue to flow past that point.
Are you for real

We have pressure on one side,and vacuum on the other,and you think the water wont flow?
Go place your two hands in a tub of water,and move them fro left to right together-->with a gap of say 1/2 a foot between your hands. Your left hand is creating a pressure ,and your right hand is creating a vacuum on the body of water between your hand. Will the water between your hands move? will there be a point in that volume of water where the pressure and vacume are equal,and will that water still move?

[tinman]

Below is a diagram of a very simple jet pump,same type as used in jet skie's.
The suction pressure on the inlet side is the same negative value to that of the outlet side when inlet and outlet nozzles are of the same size. It will remain the same(minus water flow friction in the pipes) until a point of cavitation is reached-and then there is trouble. But as you can see in my previous diagram,at those pressures no cavitation will occur.

[Cap-Z-ro]

Looks like we have stumbled onto a subject that you know little about Mark. You do kknow what a jet pump is!dont you?!
Lucky for me,i have been working on pumping systems for over 25 years on mine sites,and knowing this sort of information was a must and part of our training.

The pressure and vacuum reach equilibrium exactly where i have depicted the pressure gauge(minus a very small amount due to friction within the pipes) that reads zero when all pipe sizes are equal in size and length,and a jet pump is used-as i also depicted.

Quote: Were the pressure actually zero at the middle of the upper pipe segment, there would not be any impetus for water to continue to flow past that point.
Are you for real

We have pressure on one side,and vacuum on the other,and you think the water wont flow?
Go place your two hands in a tub of water,and move them fro left to right together-->with a gap of say 1/2 a foot between your hands. Your left hand is creating a pressure ,and your right hand is creating a vacuum on the body of water between your hand. Will the water between your hands move? will there be a point in that volume of water where the pressure and vacume are equal,and will that water still move?

Beware of tarbaby's...they are extremely sticky...3 foot clearance is the recommended distance.

Regards...

[allcanadian]

@Mark E

You have chosen an arbitrary location for your pressure zero.  The pressure falls from the pump outlet all the way back to the pump inlet.  Were the pressure actually zero at the middle of the upper pipe segment, there would not be any impetus for water to continue to flow past that point.

However if we were to add a slight restriction or boundary condition at the middle where the pressure gauge is located then everything works perfectly which is of course applied mechanics 101. In a closed system as velocity increases the pressure decreases and the energy is then not in the pressure but the momentum ie. mass velocity of the fluid.


It is common sense, you cannot have a positive pressure at one end and a negative pressure on the other without the pressure passing through zero somewhere in between. Otherwise one must presume some spooky action at a distance must have taken place and well... that's just silly.


AC

[MarkE]

@Mark E

However if we were to add a slight restriction or boundary condition at the middle where the pressure gauge is located then everything works perfectly which is of course applied mechanics 101. In a closed system as velocity increases the pressure decreases and the energy is then not in the pressure but the momentum ie. mass velocity of the fluid.


It is common sense, you cannot have a positive pressure at one end and a negative pressure on the other without the pressure passing through zero somewhere in between. Otherwise one must presume some spooky action at a distance must have taken place and well... that's just silly.


AC

LOL, place a differential pressure gauge across your restriction and tell me which side of the restriction it indicates has the higher pressure.