Mailing List Archive Mailing List Archive
All >The question of how long it takes the mix to completely homogenize is still >subject to some debate, but it really has nothing to do with the situation >you are describing - any error it caused would have shown up immediately >after mixing, not much later when you saw it (unless of course the guy was >analyzing instantly upon mixing, then wasting hours fiddling with the mix >to try and "correct" it, in which case the guy is an even bigger idiot. For most of the last year I have been mixing my own gas and can comment with limited experience on this. Nitrox seems to mix completely sometimes immediately after filling or at least within 5 minutes of filling. I leave my analysis of Trimix fills until the next morning. I have seen Trimixes take 2-3 hours or more to stabalise. BTW, I pump each gas in one after each other rather than waiting hours for the He then O2 to cool. Interestingly over the weekend, my buddy took a 25 litre twinset with something like 36% in it and connected it via a whip to a 7 litre cylinder containing the devil gas (air). All cylinders were full at about 220 bar to start. He reported that after 1.5 days, the O2 content of the cylinders had only changed by 1.7% up and down. I haven't repeated his experiment but what it shows if that the diffusion of the gasses is relatively slow if this has to occur by Brownian motion across the whip, etc. rather than being mixed by a jet of high pressure gas being injected into the cylinder as is the case when a cylinder is filled. David Shimell Project Manager, Sequent Computer Systems Ltd, Weybridge, UK Email: shimell@se*.co* ---------- From: owner-techdiver[SMTP:owner-techdiver@aquanaut.com] Sent: 25 February 1998 10:29 To: techdiver Subject: Re: nitrox >His explanation was that he had someone else do the fills. The new person >did not wait long enough between the time the tank was filled to do the oxygen >measuring. He says that the additional time is needed so the oxygen can mix. >Has anyone ever heard of such a thing? This has nothing to do with it. You don't analyze a mix to tell you what it is - you analyze it as a double-check to confirm that it came out as intended. If the mix is off, then it's because the mixing was done wrong, not the analysis. Whoever is doing the mixing there doesn't know what the hell they are doing, and you are right not to trust them anymore. But weren't you analyzing your mixes before diving all along?? The question of how long it takes the mix to completely homogenize is still subject to some debate, but it really has nothing to do with the situation you are describing - any error it caused would have shown up immediately after mixing, not much later when you saw it (unless of course the guy was analyzing instantly upon mixing, then wasting hours fiddling with the mix to try and "correct" it, in which case the guy is an even bigger idiot. 5% is a hell of an error. It boggles the mind how anyone could get that far off. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]