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Water suction
- Thread starter p kansik
- Start date
It might pull it up 6m or so.
Theoretically it might be as high as 10m, but that's pretty difficult to achieve in practice.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
Theoretically it might be as high as 10m, but that's pretty difficult to achieve in practice.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
LittleInch
Petroleum
If the container is fully sealed and totally filled with water (no air) then you might just be able to get water lift. Your weight can create a negative pressure close to 0 bara [EDIT ERROR] and you need min 0.2 bara to "lift" the water. Forget weight of either of these things, it's pressure which is the key.
However entrained air in the water will start to bubble out and you don't mention temperature. water will start to boil at reduced pressure dependant on temperature. At 25C its 0.03 bar. Still low but you have very little spare. 30C its 0.042. Also what elevation are you above sea level? Every 100m makes a difference as it is this pressure which pushes the water up the pipe.
As Mr 44 says, you're at the ragged edge here. Any amount of air or vapour and the cylinder will fall, but very little water is drawn up the pipe.
7 m I would say yes[ EDIT - NO WONT WORK], 8m is marginal, 9m no way in practice.
Is this a real question or homework? How do you lift your 3 tonne weight to repeat the pumping?
got any pictures?
Why not use a submersible pump?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
However entrained air in the water will start to bubble out and you don't mention temperature. water will start to boil at reduced pressure dependant on temperature. At 25C its 0.03 bar. Still low but you have very little spare. 30C its 0.042. Also what elevation are you above sea level? Every 100m makes a difference as it is this pressure which pushes the water up the pipe.
As Mr 44 says, you're at the ragged edge here. Any amount of air or vapour and the cylinder will fall, but very little water is drawn up the pipe.
7 m I would say yes[ EDIT - NO WONT WORK], 8m is marginal, 9m no way in practice.
Is this a real question or homework? How do you lift your 3 tonne weight to repeat the pumping?
got any pictures?
Why not use a submersible pump?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
The piston will not fall unless you pull it down. It only takes 1.356 psi vacuum pressure to keep the piston suspended considering a perfectly sealed system and zero clearance between piston and top of cylinder. 1.356 therefore is the maximum vacuum possible at the downstream side of the pipe or in absolute pressure terms 13. 3 psia absolute unless you force the piston down. Add to this pressure the pressure of the static liquid height of about 11.37 psi for a total pressure acting down of 24.7 psia acting on cross sectional pipe area to give force. Acting up at bottom of pipe is atmospheric pressure of 14.7 psia plus static pressure of depth of pipe in water (assume negligible). So you have a net force down of about 10 psi times area which is balanced by the check valve at the bottom. Fluid won't move until pressure at bottom is equal or slightly lower on the downstream side of the bottom check valve. You need to develop 10 psi more vacuum before the fluid will begin to move.
LittleInch
Petroleum
Ah, sorry, got my digits wrong.
You are only pulling 0.1 bara pressure which is 1m lift max, without taking into account any friction losses in the pipe or static losses through the NRVs.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
You are only pulling 0.1 bara pressure which is 1m lift max, without taking into account any friction losses in the pipe or static losses through the NRVs.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
- Thread starter
- #8
Probably,
what happens when you fill container B
how do you return the piston to its original position
is it a continuous operation.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
what happens when you fill container B
how do you return the piston to its original position
is it a continuous operation.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
LittleInch
Petroleum
So what are you going to do now?
If you kept the weight but reduced the surface area of the piston by a factor of 10 it might work...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
If you kept the weight but reduced the surface area of the piston by a factor of 10 it might work...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
No matter what happens at the cylinder, due to the practicalities of suction lift, he will still only get 6-7m.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
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