Air compressor's

[ccuda]

Yes, Yes, and Yes.
Work the situation in reverse to get to your starting point.  You are responsibile for what went inside your buddys' equipment, more importantly what went inside their bodies for life-support, and what you provided them becomes concentrated at depth.  With that said, every precaution and insurance is a must, your potential liability just went through the roof. 

Buy the best you can afford, maintain it and have it inspected and tested extensively on a regular basis, dont cut corners in any way.  Simply do everything you can to avoid your EX-buddy's lawyer filing suit and taking everything you own and seeking criminal prosecution.  When the project starts to include and affect others, it definitely becomes a bigger picture.