I wrote an article about cost-justifying the purchase of a compressor for garage brews more than a decade ago.
The bottom line was that it is not a viable alternative given that there is someone reasonably close willing to sell you a decent fill at a reasonable price.
The situation has not changed much in my opinion.
To some extent, the data used in that article came from running my own fill-station. I supplied students and my dive buddies with Nitrox and Trimix. I had all the paperwork, insurance, business license, blender certification and checks and balances in place.
On average and with costs amortized over 12 months, filling a cylinder with air (the size and working pressure are virtually immaterial but for the sake of argument I used a 14 litre cylinder charged to 210 bar as my default) cost me about twice what the local shop was charging. Nitrox was slightly better, but not much, and trimix was a lot better (but helium then was about 1/8th what it costs today) but those savings did not compensate for the setup and running costs... and this was when I was logging around 100 trimix dives a year.
It WAS more convenient, but not less costly.
The bottom line was that it is not a viable alternative given that there is someone reasonably close willing to sell you a decent fill at a reasonable price.
The situation has not changed much in my opinion.
To some extent, the data used in that article came from running my own fill-station. I supplied students and my dive buddies with Nitrox and Trimix. I had all the paperwork, insurance, business license, blender certification and checks and balances in place.
On average and with costs amortized over 12 months, filling a cylinder with air (the size and working pressure are virtually immaterial but for the sake of argument I used a 14 litre cylinder charged to 210 bar as my default) cost me about twice what the local shop was charging. Nitrox was slightly better, but not much, and trimix was a lot better (but helium then was about 1/8th what it costs today) but those savings did not compensate for the setup and running costs... and this was when I was logging around 100 trimix dives a year.
It WAS more convenient, but not less costly.
Didn't you see all the laughter......
