| Imported post
He analysers are really bloody expensive & I have to say I don't feel it's necessary to blow all that dosh.
As long you put a known quantity of all the relevant gases in an empty bottle- if the O2 analysis measures up to your calculations, the He will be correct also. It gets a bit trickier if you're doing subsequent tops but tables do exist to let you calculate what the projected He component will be after, say, an air,O2 and He top.
The thing with He is a few percent either way is not necessarily as much of a problem as it would be with O2 - you'll be slightly more or less narked depending on the error, but I wouldn't let an error of up to 5% make any difference to my deco obligations for example.
A fresh Heliar/Trimix fill can be calculated to within 1 percent even using a whip if you've got a decent enough guage on it.
I suppose if you thought your LDS was pulling a fast one with your fills it might be handy .. |