A compressor system to grow with

[pescador775]

You received some good advice from Curley and others. Buying a suitable compressor is a big decision for most folks. In this case, a heavy, slow turning installation is the way to go. This could be a Bauer Mariner or K14, or even an Ingersol Rand or Davey depending on what kind of deal you can swing. The four stage compressor has more moving parts but should be more reliable in jamming high pressures at high ambient temps. Anyway, you need to think ahead. Trimix blending can be done with a homemade mixing stick but liability could come into play with DIY gear. I don't see a liability problem if the mix is done right regardless of the type of system but an insurance company might not see it that way. If a stik is not used then one must consider the expense of helium and the need to purchase a booster. This brings one back to the mixing stik which depends on gas flowing through the compressor. Since helium can generate a bit more heat in a compressor this would tend to weigh in favor of the four stage; but, if the compressor is not to run for more than an hour or so it probably doesn't matter. It may not be an issue at all so don't give it too much weight in the decision. Get something in the 7 cfm range and build a mixing stik. Buy a copy of the Oxygen Hackers Companion. (whisper) Don't tell your instructor.