I recently got an Umarex Notos, which I am thoroughly enjoying. I very quickly realized however, for my plinking habits ~25 shots per fill is just not enough. 
I realized I was spoiled having started with an Avenger and getting 120 shots per fill. I looked at various cylinders, and wanted to start small (cost, as well as my cheap pump probably wouldn't handle a large cylinder). I wanted to get a feel for what a very small portable cylinder would get me. I do plan to get a YH in the future, and will likely get a larger cylinder then.
I have seen Stubber's calculator, but it is focused on larger tanks and I wanted to see not just how many complete fills, but also what incomplete fill pressures would be as the cylinder dropped below the max pressure of the airgun. That way I could get an idea of what as small (0.5L) cylinder would get me. I created a simple spreadsheet to estimate the fills and pressures (hopefully its accurate), and figured I would post it in case it was useful to anyone else.
On another note, Christmas brought me the 0.5L cylinder and valve I decided on after playing with the numbers. The estimation seemed to work, and I got three full refills on my Notos stating from a bit below 300bar in the 0.5L cylinder and shooting 3 magazines between fills (21 shots - probably still a little over the reg pressure). That is about what the spreadsheet predicted. I was also able to fill the 0.5L cylinder from empty without issue I stopping whenever the compressor temp got to 40C and resting for 15-20 min - complete fill needed 12min first run, 8 min second and third runs, and a 4 minute run to final pressure just below 300 bar. I stayed a little low because the guages on the compressor and the cylinder valve disagreed a bit, so I stayed on the safe side.
View attachment PCP refill by cylinder.xlsx
I realized I was spoiled having started with an Avenger and getting 120 shots per fill. I looked at various cylinders, and wanted to start small (cost, as well as my cheap pump probably wouldn't handle a large cylinder). I wanted to get a feel for what a very small portable cylinder would get me. I do plan to get a YH in the future, and will likely get a larger cylinder then.I have seen Stubber's calculator, but it is focused on larger tanks and I wanted to see not just how many complete fills, but also what incomplete fill pressures would be as the cylinder dropped below the max pressure of the airgun. That way I could get an idea of what as small (0.5L) cylinder would get me. I created a simple spreadsheet to estimate the fills and pressures (hopefully its accurate), and figured I would post it in case it was useful to anyone else.
On another note, Christmas brought me the 0.5L cylinder and valve I decided on after playing with the numbers. The estimation seemed to work, and I got three full refills on my Notos stating from a bit below 300bar in the 0.5L cylinder and shooting 3 magazines between fills (21 shots - probably still a little over the reg pressure). That is about what the spreadsheet predicted. I was also able to fill the 0.5L cylinder from empty without issue I stopping whenever the compressor temp got to 40C and resting for 15-20 min - complete fill needed 12min first run, 8 min second and third runs, and a 4 minute run to final pressure just below 300 bar. I stayed a little low because the guages on the compressor and the cylinder valve disagreed a bit, so I stayed on the safe side.
View attachment PCP refill by cylinder.xlsx
