Helium costs

[roakey]

Like I said, it’s mined. There’s not enough in the atmosphere to seperate it out and isn’t bound chemically into any compounds that it can be split apart to yield it like Hydrogen.

Thanks for the 1-3% number for loss from a Dewar/day; that makes it quite clear that LOX's not something I want to look into!

Roak

 

[MikeFerrara]

So...I guess I pay more for He than everyone else.

 

[Ray2]

Roakey,
A better term might be Cryogenic Distillation.it just hit me
same process I guess.As for Lox a driver tipped over a Dewar
it ruptured spilling liquid on the bed of his truck ignighted and
he died in the fire.Also a good friend was filling a dewar and the
valve broke off filling his glove with Lox and it went down his
shirt,legs and into his shoes needless to say he has not worked
for a couple of years but seems to be making a full recovery.
Handle all liquid dewars with care
Ray

 

[roakey]

MikeFerrara once bubbled...
So...I guess I pay more for He than everyone else.

Not much more than me, I think my T cost $65.

Ray2, even more reasons to stick with the gas version!

Roak

 

[Tibbs]

Not that I dive He (yet), but friends of mine pay up to 2p per litre of Helium. Since a twinset of 21/35 (2 x 12L cylinders) needs 1948.8 litres of helium for a 232bar fill - that's quite a lot of money! (£39.98 about $58 in your money).

Luckily I'm the member of a club so I would 'only' pay 1p per litre...

Chris

 

[padiscubapro]

Ray2 once bubbled...
Roakey,
Fractional distillation 'I belive is a process that is used in the Oil industry and it involves heating, in this case crude oil, and collecting the different chemicals as they reach a certain temp.but Im pretty sure this process can be used different applications.The Molecular Sieves are not used to separate the common gases,the main use for them is removal of mosture ,Co2, Hydrocarbons and quite a few other elements, its a purifier.Air separation or reduction plants are where we produce O2,N2 and Ar,the process starts by pulling air from the atmosphere down a vertical stack using the venturi effect
the gas separates as it reaches the right temp, very cold ,smiley face here.It then goes to storage tank for distribution.Keep in mind this is a very basic description of the process.
Ray

Membrane systems that produce nitrox, are molecular sieves also.. they work by letteing certain size molecules pass while others are trapped..
Oxygen generators where large volumes are not required use this method.. Most can generate 2000psi in a T cell in a day(93-96% is common), ones with an extra booster stage can do 3000 psi.

 

[Ray2]

Padiscubspro'
Yes, you are correct in your desciption of the membrane sys.
Here is what the book says"Mol. Sieves are synthetically
produced,crystalline metal aluminosilicates that have been activated for absorbtion by by removing their water of hydration.
Unlike other absorbents, Mol. Sieves have a precise uniform size
and molecular dimension. According to the size of these pores, molecules may be readily absorbed,slowly absorbed or completely
excluded.This sieve-like selectivity,based on molecular size,plus a selectable preference for polar or polarizable molecules,gives molecular sieves an extremely high level of absorbtion efficiency,
and permits close tailoring of the absorbent to the specific use.pore sizes vary by the type molecular sieve" and it give sizes
in angstoms. WoW, this will give you a headache quick I have a couple of home med. suppliers and they use the a similar type of O2 concentrator that produces approx. the %'s you stated.It is my understandiding this is reason why Medical O2 standard is only 95%.You guy's are are making use my brain too much, maybe
its the beer,I dont know?
Ray

 

[Jonathan]

Trimix is finally available in Japan - my instructor proudly told me 2 nights ago. So now he can sell the trimix courses!!

Only problem is: 20/40 (have I got that right 20% O2, 40% He?) in 2 x 12l is (drum roll please) 20,000 yen

To translate that is $170 or £110

He was not too upset when I said I would still do my cert in another country.

Just some food for thought.....

 

[Uncle Pug]

Jonathan once bubbled...
To translate that is $170

Move!

 

[Jonathan]

I will - eventually! But probably not till the end of next year.

Anyway the chances of me doing trimix diving here are very remote, they get upset if you are in the water for more than 40 minutes and only one or two skippers will let us do deco.

Should mention that a 12l nitrox fill is $25 - but then that does come in range of an expat package....

Jonathan