Inquiries about pressurized air

[harry ravi]

Bonjour,

I am not an expert in physics and therefore I ask myself the question about the pressurization of the ambient air:

let's say I have 1M cube of air at ATM pressure and want to get 100bar of pressure from a piston that will compress the air using the gravity of the earth.
What would be the mass of this piston? 100kg?

Also, with the current state of research on presurized air conditioning, what air pressure can I achieve in a storage tank?


Thanks for reading me

[harry ravi]

I just remembered an old physics course, I forgot the notion of mass applied to a surface.

If I want a pressure of 100 bars on 1cm² of air, do I have to apply 100kg of weight perpendicular to the earth's surface on that surface?

Using a density lead piston (11 kg / m340), the height of this piston should be:

113,40kg for 10 dm3
1cm x 1cm x 10m = 10000cm3 = 10dm3
10x100/113,40 = 8,82dm3
To have 100kg of pressure on 1cm² of air, I must have a lead piston with an author of 8,82m.
We could reduce this height by 2 by using the turntable but I think it is quite expensive.

By having a lead piston with a radius of 1m and a height of 8,82m we have:
Pi * 1 * 8,82 = 27,70m3

Or a weight of 11340 * 27,70 = 314118kg = 314,118Tons

Can you tell me if my approach is good?

[Ahmed]

The approach seems good compared to the very optimistic initial estimate, it remains to check the calculations (without me!). In view of the results which do not surprise me, what can be the interest of this procedure?
In addition, 100 bars is quite considerable, usual compressors go up to a maximum of 10 bars.

[harry ravi]

Yes I know, it's just to see if the calculation method is right.

The results don't surprise me either.

Another question: with this same piston which is supposed to compress ambient air to 100 bars, can I compress as much air as I want in the compression chamber? Whether I put 1m3 or 100m3 of air under the piston, will I find 100bars of pressure whatever happens?

[elephant]

Common "low pressure" pressures are in the range of 4 to 16 bar. (the industrial standard pressure being 7 bars).
However, for gas storage and nitrogen / oxygen separation applications, 200 bars is a common value.
Lemonade bottles are blown at 40-50 bars
It is obvious that we then enter the field of "PED" certifications: tubes, certified tank bottoms (up to 20 X more expensive), certified welders, etc.
Generally, multistage compressors are used and, to achieve the highest pressure, diaphragm compressors, where there is no more leakage between the cylinder and the piston.
Of course, at these pressures the air must be perfectly dry and clean.

[Christophe]

What would be the mass of this piston? 100kg?

Toutafé ... provided that its surface is 1cm² you could obtain 100 bars in one stroke thanks to gravity!

But what is the real purpose of your question?

ps: I see that you found the answer yourself after ... sorry

[harry ravi]

Something is going through my head and I want to see if it's doable.
I keep you posted whether it is on track or totally outlandish.

[micdhi]

Hello
PXV = constant
and 1 bar = 1 kg (approximately) per cm2

therefore, as he said above, to obtain 1 bar in 1 cm2 you need 100 kg.
to get 100 bars for 10000cm2 (100cm x100cm, base area of ​​your m3) you need 10 tons of pressure (thrust), and result you get 10000cm3 of air, 10 liters of air at 100 bars

[Lietseu]

Something is going through my head and I want to see if it's doable.
I keep you posted whether it is on track or totally outlandish.

At any risk, there are compressors for scuba diving that fill the diving tanks at + 200bar!

The bottles are tested at 300bar in tanks with pressurized oil (the oil can not explode the bottle not being compressible, like all liquids)

To gain a few minutes of autonomy in diving, some members of my club did not hesitate to turn the compressor mano to 230bar ... unconscious, isn't he?

Versperal greetings!

[harry ravi]

Hello
PXV = constant
and 1 bar = 1 kg (approximately) per cm2

therefore, as he said above, to obtain 1 bar in 1 cm2 you need 100 kg.
to get 100 bars for 10000cm2 (100cm x100cm, base area of ​​your m3) you need 10 tons of pressure (thrust), and result you get 10000cm3 of air, 10 liters of air at 100 bars

Ok for the beginning of the explanation but for the 10L of air at 100 bars, everything depends on the initial volume.

With 1m3 of air at atmo pressure, I will obtain with 10tones of pressure, 10L at 100bars ....

Now if I extend the compression chamber to have 10m3 of air, if I apply 10 tones of pressure, logically obtains 100L of air at 100 bars ....

This weekend I am attacking part of my concept.

Theoretical question: imagine 10L of air at 100 bars.
Imagine an air turbine with an efficiency of 100% where I apply an air pressure at 5 bars (so I have 200L of air at 5 bars in the tank)
How many kinetic watts can I get with these 200L of air at 5 bars?

Some info is surely missing, I'm waiting for your additional information.