What is "foot valve",why it prevents loss of prime

[rjmack]

mmurphy; thanks, i missed one of your posts, so that caused some confusion.

so, i'm guessing the efficiency of the impeller design determines the maximum working pressure of a non-positive displacement pump?

 

[mmurphy]

mmurphy; thanks, i missed one of your posts, so that caused some confusion.

so, i'm guessing the efficiency of the impeller design determines the maximum working pressure of a non-positive displacement pump?

Yes, along with impellar diameter and rpm.

 

[Egon]

The diameter and rpm will dictate the volume of fluid moved. The number of stages dictates the pressure to which the fluid can be pumped.

 

[mmurphy]

The diameter and rpm will dictate the volume of fluid moved. The number of stages dictates the pressure to which the fluid can be pumped.

Yes, that would be correct also. I am talking single impellar.
Egon, I see you were involved in waste water field.:thumbsup:

 

[Egon]

From Google

Simple operation.

While jet pumps differ in appearance, all operate basically the same way. An operating fluid under pressure enters through the inlet and travels through the nozzle -- where it is converted to a high-velocity stream which decreases the air pressure in the suction chamber, creating a partial vacuum that draws material to that area where it is entrained by the operating medium. The entrained material is then carried through to the discharge outlet and dispelled at a pressure greater than that of the suction stream but lower than that of the operating medium

A Google site that explains things much better than I ever could: It's got pictures too!

Water lifting devices

 

[turnkey4099]

Just for a bit of trivial, the maximum pump on water is 32 ft. Trying to
obtain suction of water higher than that you are just creating a
barometer.

Maximum suction head varies for different liquids based on the specific gravity
of the material in question.

32 ft suction lift for water is the theoretical at sea level. Practical, due to pump inefficiency, pipe friction, etc. is generally figured at 26ft.

You figure the 'lift' from the static level of the well, not where the foot valve is located (or in the case of submersibles, where the pump is located). Of course the drawdown of the well has to also be considered.

Thus a 100 ft well with static of 70 ft you will need a submersible, a suction pump won't work.

Harry K