WetCell
Contributor
Please be tolerant. I'm working from memory.
When I learned to dive back in the 1960's, someone was marketing a single cylinder scuba compressor. It would only pump to about 2,500 psi. It was tiny and fairly inexpensive.
If I recall correctly, it had a piston about half an inch in diameter and took several hours to fill a steel 72. Mako comes to mind, but I wouldn't swear that they had marketed them.
I actually saw one once. It wasn't in serviceable condition. Evidently, the single piston and cylinder would get outrageously hot. The heating and cooling cycles would crystallize the piston and cylinder and in a few hundred hours, it would go bang. It was a great idea, but with affordable materials, it simply wouldn't work. I guess that something similar could be made today, using materials like inconel, 9 nickel cobalt, and beryllium copper alloys, but the cost would be insane.
The point here is that anything can be done, given sufficient money. If there was a way to build a small, inexpensive compressor to fill scuba tanks, someone would be all over it. The market is ready.
Technology is available to do virtually anything that can be imagined. In the end, it will always come down to cost. The military compressors cross the cost benefit line by a substantial margin. They are vastly better made than the commercial units of similar size. Cost was a consideration in their design, but only in a secondary sense. Longevity, reliability, and weight took top honors.
In many cases, economy of scale will drive costs down but not with the materials I mentioned. Some things are so difficult to machine that very few people on the planet can even do it (9 nickel cobalt is one of those materials). In those cases, economy of scale is just a dream.
You can have it good, cheap, quick. Pick two.
I work in the aerospace industry. We face these decisions on a daily basis. We do not resort to exotic materials if any reasonable alternative exists. This is just reality and the same reality that compressor designers and manufacturers have to consider.
Bill.
I'd like to see that circa 60's system. That is exactly the idea. As you no doubt know, many great ideas have had to wait for the technology or science to catch up. Based on what I have seen, I think the time is ripe for the system out in the garage puttering away for a few hours--especially given the fact that the NG systems are coming online, which use the same concept at the same pressures.
Of course, many ideas that finally get into production die on the vine of the marketplace because no one picks them. I think a reliable, easy to use, inexpensive to maintain system that came in at under $1K might be well received in the scuba market.