Air Arms Owners Club

could not quite understand the chart in another thread so could someone give me a rough idea how many fills I can roughly expect from a 3 litre air bottle for my S200 mk3 in .22. Many thanks

Lets apply some O level physics

Assumptions
1. Air is an ideal gas at constant temperature throughout so
converting all air to free atmospheric pressure...
V2 = V1 * P1 / P2
2. Tanks start at 300 bar and finish up at 180 bar before refilling
3. Gun cylinders filled to 180 bar and are used down to 120bar
4. Gun cylinder is 2.8cm inside diameter and 30cm long (s400 MPR)
so gun volume is 2.8 * 2.8 * 30 * 3.142/4 = 185 cc = 0.185 litres
5. Tank volume is 3 litres
6. No losses
7. Atmosphere is 1 bar.
Using the formula...
Volume of free air in a full 3 litre 300 bar tank is 3 * 300 / 1 = 900 litres
Volume of free air remaining in tank at 180 bar is 3 * 180 / 1 = 540 litres
So air available to fill the gun is 900 - 540 = 360 litres.
Similarly,
Volume of free air needed to fill cylinder from 120 to 180 is
0.185 * (180 - 120) / 1
= 11.08 litres

Therefore fills for this scenario is
360 / 11.08

= 32 fills

Plug your values into this!

Brilliant

But it made my head hurt

I'm having a lie down. Its been 52 years!

Out of interest my 7 litre 232 bar tank on the same gun cylinder using the same parameters as above will give 33 fills compared with 32 fills from a 3 litre 300 bar tank.
That kind of ties up with filling every one or two weeks for a year.

I thankyou by the way whats an O-level physics ???

Gerry CN wrote:I thankyou by the way whats an O-level physics ???

Proper education before Keith Joseph buggered about with the curriculum and you knew watt was watt and ohm was where the heart was.
I would also like to thank Katie Boyle for the gas laws.

TenMetrePeter wrote:

Gerry CN wrote:I thankyou by the way whats an O-level physics ???

Proper education before Keith Joseph buggered about with the curriculum and you knew watt was watt and ohm was where the heart was.
I would also like to thank Katie Boyle for the gas laws.

Watt was definitely Watt and ohm was definitely ohm in them days and Katie Boyle was most definitely a Gas especially when the lady was cooking up a storm.