What fluid is used in hydraulic lift??
can mercury instead of watr in hydraulic lift be more useful??
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It all has to do with how to transfer force from the source to move what you want. While liquids (such as water) seem to be in-compressible, they actually follow the natural gas law along the curve as if the water was already compressed to about 300K psi. What this means is at 6k psi water will only compress about 2% so if you were down about 4km in the ocean, then the water only takes up 98% as much space as on the surface.
Now it is easy to use machinery to generate pressure, the trick is to get that generated pressure to some other location so it can be put to useful work. You don’t want to have lots of machinery every place you are doing work or moving a joint. If you use piping or hoses, you can move that potential energy to various other locations for ease of use. However, if you use air which is highly compressible, then moving the pressure to a remote location (like the end of a backhoe to move it) it has a lot more variability once you get it moving. So if you put 100 cubic inches of air (to fill up a ram) at 100 psia (pounds per square inch absolute) and put it in a situation that will compress it to 700 psia, it will shrink to about 1/7 of its original volume. Likewise the liquids will only compress about 0.2% with even a 600 psia pressure differential.
Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. A barometer using water, for instance, would need to be 13.6 times taller than a mercurybarometer to obtain the same pressure difference.
Now it is easy to use machinery to generate pressure, the trick is to get that generated pressure to some other location so it can be put to useful work. You don’t want to have lots of machinery every place you are doing work or moving a joint. If you use piping or hoses, you can move that potential energy to various other locations for ease of use. However, if you use air which is highly compressible, then moving the pressure to a remote location (like the end of a backhoe to move it) it has a lot more variability once you get it moving. So if you put 100 cubic inches of air (to fill up a ram) at 100 psia (pounds per square inch absolute) and put it in a situation that will compress it to 700 psia, it will shrink to about 1/7 of its original volume. Likewise the liquids will only compress about 0.2% with even a 600 psia pressure differential.
Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. A barometer using water, for instance, would need to be 13.6 times taller than a mercurybarometer to obtain the same pressure difference.
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Firstt of all we dont use water there. We use oil. Using mercury will Increase the cost and make the whole thing massy enough as mercury is too heavy.
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