PSI and compressors

[nickyhansard]

If you had two tanks of relatively similar PSI (one slightly less than the other). Would the compressor needed to transfer gas from the lower PSI tank to the higher PSI tank simply have to raise the PSI to above the higher tank PSI to transfer gas.

 

Basically would a weak compressor still be able to get the job done? Seeing as it only has to comparatively raise the PSI a few points?

 

I ask because I was thinking in terms of robotics. If you used compressed air to actuate movement, could you use two tanks to achieve this. Have one tank as the primary (with the larger PSI) and another slightly lower PSI tank as the secondary. So when you use the higher PSI tank to move a piston for instance, could you vent the gas to the lower PSI tank (which should be automatic because the PSI in the secondary tank should be lower) and than have a low power compressor to transfer gas from the lower PSI tank to the higher PSI tank?

 

High PSI tank > piston > low PSI tank > compressor > high PSI tank

 

I would assume only running the compressor when the primary tank reaches a certain threshold would be the most efficient way to save power.

 

You could have a piston in a cylinder that has an inlet from the high PSI tank (primrary) on either end of the cylinder along with a relief valve on both ends connected to the low PSI tank (secondary). So when one side is receiving gas from the primrary tank the relief valve on the opposing side is venting to the secondary tank.

 

Although now I'm thinking I'm missing a vital point. If their PSI is similar than you're only getting the difference between the PSI in the tanks pushing the piston... Lol I suppose I could atleast start with a pressurised tank and an empty tank and create a closed system... Better than nothing and I imagine still more efficient than an open system.

Edited October 28, 2014 by nickyhansard

[arc]

You answered your own question. Trying to recover your expelled air would require an expenditure of at least an equal amount of energy to compress the air into the secondary tank. Even an empty tank would gradually require more energy from the first tank as it is filled, using the same energy you wanted to use for the robotic systems. Pneumatics need an open system to operate.

 

You could recover some heat from the compressed air though.

Edited October 29, 2014 by arc