Hi .
Purpose of question .
Work out the atmospheric pressure available within a cylinder , pre compression .
So then can work out , a compression ratio .
Gain desired or expected psi of the compressed air part / after the compression.
Atmospheric pressure is stated at 14.7 psi per inch squares ( in2.)
Easy to work out volume of cylinder .
Cubic inches ( in3)
Where I get unstuck part .
Converting that in3 into in2 .
Or is there another way to go about this .
Hope that makes sense .
Thanks .
How do you convert in3 into in2
 mrfoo
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Boyle's Law. Not Susan Boyle.
For a given mass of confined gas at constant temperature, pressure multiplied by volume will be constant.
So for a starting state at pressure P₁ with chamber volume V₁, and a compressed state P₂ with final chamber volume V₂ :
P₁V₁ = P₂V₂
This gets combined with Charles' Law and  ummm  I forget  GayLussac I think  to give the ideal gas law, which is pretty much what you need. This adds a new factor, temperature, and can be expressed variously as
PV = nRT
where n is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature in °K (no freedom units here, it's science)
or
P₁V₁ / T₁ = P₂V₂ / T₂
Again, temperatures are absolute.
TL/DR version  ignoring temperature changes, if you halve the volume, you double the pressure. That will get you pretty close.
For a given mass of confined gas at constant temperature, pressure multiplied by volume will be constant.
So for a starting state at pressure P₁ with chamber volume V₁, and a compressed state P₂ with final chamber volume V₂ :
P₁V₁ = P₂V₂
This gets combined with Charles' Law and  ummm  I forget  GayLussac I think  to give the ideal gas law, which is pretty much what you need. This adds a new factor, temperature, and can be expressed variously as
PV = nRT
where n is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature in °K (no freedom units here, it's science)
or
P₁V₁ / T₁ = P₂V₂ / T₂
Again, temperatures are absolute.
TL/DR version  ignoring temperature changes, if you halve the volume, you double the pressure. That will get you pretty close.

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Ta Mrfoo .mrfoo wrote: ↑Fri Dec 02, 2022 1:14 pmBoyle's Law. Not Susan Boyle.
For a given mass of confined gas at constant temperature, pressure multiplied by volume will be constant.
So for a starting state at pressure P₁ with chamber volume V₁, and a compressed state P₂ with final chamber volume V₂ :
P₁V₁ = P₂V₂
This gets combined with Charles' Law and  ummm  I forget  GayLussac I think  to give the ideal gas law, which is pretty much what you need. This adds a new factor, temperature, and can be expressed variously as
PV = nRT
where n is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature in °K (no freedom units here, it's science)
or
P₁V₁ / T₁ = P₂V₂ / T₂
Again, temperatures are absolute.
TL/DR version  ignoring temperature changes, if you halve the volume, you double the pressure. That will get you pretty close.
Ok.
Wow , learning curve ...lol.
I ran with this .
Or should I just used standard definitions?
( Are a few )
Particular where live in world.
311 meters above sea level =
14.1766 psi (97.74421624 kpa)
25 deg C ( 298.15 Kelvin)
Molar volume of gas ,
P.V= n.R.T
which can be rearranged :
V/n = (R.T) /P
where (in SI metric units):
P = the gas absolute pressure, in kPa
n = number of moles, in mol
V / n = the gas molar volume, in m³/mol
T = the gas absolute temperature, in K
R = the universal gas law constant of
8.3145
V/n= 8.3145 X 298.15 / 97.74421624
= 25.3617904835 m3/ mol.
Equiv to litres ?
Then ran with .
Break down to cm3 ( X 1000)
14.1766 psi / 25361.7904835 cm3 .
Psi Per cm3 = 0.00055897473
Not ( gauge pressure )
application too .
26.47 cm3 cylinder .
X 0.00055897473
=0.0147960611031 psi atmospheric pressure in above mentioned cc cylinder .
Boyles Law .
Initial parameters
Initial pressure (p₁)
psi 0.0147960611031
Initial volume (V₁
cm³ 26.47
Final parameters
Final pressure (p₂)
Psi 65.28
Final volume (V₂)
cm³ 0.006
Then Took a stab .
To compress 65.28 psi .
Is equivalent to 4.59 kgcm2 force .
Other than that .
Done my head in ....lol.