OT, but: That would be because it's rare and hard to extract and running out. It's only cheap in the US because in 1996 some genius passed a law requiring it to be sold cheaply to use up the US's helium reserves.
The likely result is that the world will be basically completely out of helium by about 2050. Too bad for anyone not-very-rich who needs an MRI scan at that point.
I'm betting we'll switch to hypoxic hydrogen ("Hydrox") for deep (>40m) diving then, or use atmospheric dive suits and ROVs only.
Hydrogen is a pain to deal with on the surface and in transport, but if you're putting it into something like 95/5 hydrogen/oxygen bottom gas, is not going to explode. At >30m, that's quite breathable. Some kind of hydrogen-based trimix is probably acceptable at that point. Continue to use nitrox and 100% oxygen for the shallow stops.
Hydrox might see some limited use for deep commercial diving (there have already been limited experiments) but it will never be rated safe for sport diving. The explosion risk at tank fill stations is ridiculous.
Definitely. There is already enough risk running high pressure oxygen given how some o-ring lubricants can react, I cannot imagine adding an additional fuel to the mix.
OT, but: That would be because it's rare and hard to extract and running out. It's only cheap in the US because in 1996 some genius passed a law requiring it to be sold cheaply to use up the US's helium reserves.
The likely result is that the world will be basically completely out of helium by about 2050. Too bad for anyone not-very-rich who needs an MRI scan at that point.
See, e.g., http://blogs.discovermagazine.com/80beats/2010/08/25/nobel-p... for more.