by TenMetrePeter » Thu Aug 17, 2017 6:38 pm
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!