Solving Hydraulic Systems with Pascal's Law - Joshua

[Barstowrat]

I think the solution I need lies within Pascal's Law, but I'm not quite sure I'm doing it right. I'm not looking for the answer to the problem, that's no fun, but I at least need the right series of formulas.

I have a storage vessel in my basement with water in it. My plan is to basically make a hydraulic ram (in theory), by adding a sealed plate with heavy weights, pressurizing it into a smaller pipe, thus supplying water to the upstairs. How do I go about figuring out what weight it is that I need for this to supply ample pressure? Or is this a completely worthless idea, meaning that it would require the weight a school bus?

My biggest problems is that all I read about Pascal's Law is the exact opposite of what I want and the formulas never seem quite right... probably because all of science exists in metric, and I learned SAE. Again, not looking for a solution to the problem, but need the way to figure it out.

Thank you,
Joshua

 

[rock.freak667]

For Pascal's Law, the pressure is transmitted equally throughout a liquid. Take the case here:

Pressure at 1 = Pressure at 2

i.e. P₁= P₂ but you know that P = F/A

i.e. F₁/A₁= F₂/A₂

Based on your piping you will have the values for A₁ and A₂. F₂ would be the weight of what you want to lift. F₁ would be how much force you would need to apply.

You can simplify the formula to make F₁ the subject to get the required force.


EDIT: I am also not sure if what you are asking is called "Pascal's Law" though.

 

[Barstowrat]

I need F2 to be @80 psi out of .5" pipe. What formula would I use to figure out how much weight its required for F1? Am I missing a step or am I just dense? LOL

 

[rock.freak667]

I need F2 to be @80 psi out of .5" pipe. What formula would I use to figure out how much weight its required for F1? Am I missing a step or am I just dense? LOL

If you have P₂ = 80 psi, then you would need to know the inlet pipe size (to get A₁).

Then just F₁ = 80A₁ which give F₁ in lbs.

 

[Barstowrat]

A1=452.16sq" • 80psi = 36,172.8lbs

Is that right? Seems a little excessive.

 

[Dr_Morbius]

A1=452.16sq" • 80psi = 36,172.8lbs

Is that right? Seems a little excessive.

Your calculation is correct.. You would need 36,173 lbs on a 452 square inch plate to pressurize the fluid to 80 PSI. The reason it seems excessive is you're using Pascal's Law backwards. Usually you use a small force on a small surface area to lift a heavier weight on a large surface area.

 

[Barstowrat]

Looks like I will have to abandon that idea. I really hoped it was going to work. Don't suppose anyone has a better idea to do this without using energy (electricity,etc)?