I have a couple of American diving magazines where there are articles on using liquid air to supply the divers. I believe the problems with different temperatures when O2 and N2 become gas again led to a number of incidents.
Probably if looked at now with the control systems available could be a way of extending dive times.
Anyway, anything incoming high pressures and gas can be dangerous. People just get away with so much
Sent from my iPhone using Tapatalk
N2 contaminated? It's exactly the same level of risk as the oxy or helium being contaminated, which we all take as a completely acceptable risk. And very probably much lower risk than the risk of a compressor filter failure.*
Since helium comes out of the ground as a minor component of a mixture of hydrocarbon gases then it depends on the level of separation which takes place before it can truly be called pure helium. I would imagine helium being suplied for welding purposes is potentially less pure than that for mixed gas blending. Yet I know that some folk do use welding grade to mix their own trimix. Never heard of an incident being attributed to this though, correct me if I'm wrong.
During the transit to the moon and return they breathed pure O2 at 0.35 bar. On the moon the suits were pressurised to 0.26/0.28 bar with O2, anything higher would have made them too restrictive and this was the minimum for life support. Its all still there, if you are planning a trip take a few bottles of O2 and some spare batteries for the lunar rovers, and plenty of sandwiches.
Last edited by thistlediver; 20-06-2019 at 07:51 AM.
If you get some verifiable information (for example from BOC) you will find that they sell various grades, the diving grade isn't anything special in terms of purity. (99.95% perhaps). 0.05% which is likely nitrogen, methane and co2, isn't going to do you a lot of harm.
Various grades mostly used for welding and laser cutting are more pure.
Can you imagine the furore and legal bill that BAE would present to the gas supplier when the contaminants fk up a few million quids worth of laser welding machine and a few million quids worth of aircraft part?
Everyone has this idea that "welding grade" is a dirty thing intended for some knuckle dragger with a roll up hanging out of his mouth in a scrapyard and it is a complete myth.
[QUOTE=WFO;433244]No you have not looked at the facts of the matter here.
I did qualify my statement with the words 'imagine' and 'potentially' . If welding grade is a higher purity than that supplied
for breathing mixtures then why is it more expensive for the latter?
There must be a cost in it which they would want to recover presumably?
If God had meant us to breathe underwater, he would have given us larger bank balances.
Human beings were invented by water as a means of moving itself from one place to another.