Jess,
  Just curious, ...What photographic processes use helium?  I am familiar
with 'nitrogen burst'. How does helium play a role?
Thanks in advance,                                                        Kent


Jess Armantrout wrote:

> this is not correct.  There are many more grades of oxygen and helium.
> There are lab grades with purities (and prices) you would not believe.  For
> example, if we had to use some of the helium used in photgraphic processes,
> we would all take up golf.
>
> The average person can get Medical o2 if he has a presciption to get it.
> This is not hard to get.
>
> Medical and aviators are identical, however, the av gas is guaranteed to
> have a lower dewpoint to prevent freezing at altitude.  The med gas is
> guaranteed to meet FDA requirements.  In reallity, they are identical, i.e.,
> ABO would meet the FDA standard and USP would meet the dewpoint standard.
> The two gases, if fact, share the same MSDS.
>
> Ironically, in some high tech welding applications, the purity requirements
> for welding gas can be *greater* than that of breathing grades of oxygen
>
> As has been stated before, all of the oxygen comes from the same place.
> Cylinder prep and tracking procedures are the only differences.
>
> Oxygen, in and of itself is not explosive.
>
> Finally, reputable gas suppliers track lot numbers on both av gas and med
> o2.
>
> For much more information, see the Air Liquide and Air Products web pages.
>
> Trout
>
> -----Original Message-----
> From: Russ Nolet <rnolet@un*.as*.co*>
> To: p k <abyss30@ho*.co*>
> Cc: techdiver@aquanaut.com <techdiver@aquanaut.com>
> Date: Sunday, November 28, 1999 11:27 AM
> Subject: Re: Isn't oxygen, oxygen?
>
> >Yes, O2 is O2 (almost!).  The highest quality O2 that is available is
> >Medical Grade, but the average person cannot get it.  The next grade of O2
> >is Avation Grade.  I do not know for sure exactly, but is most likely
> >extremely similar in quality to medical except is not certified medical
> >grade (this is what I use to mix my gas).  The poorest quality is welding
> >grade, which is not monitored at all for quality, and is not required to be
> >filtered to remove particulate matter.  From a welding perspective the
> >percentage of O2 in the tank is really not that critical.
> >
> >There are also different grades of helium.  The lowest grade is that which
> >is used for filling helium balloons, and should be avoided for diving
> >purposes, welding grade which is the next step up is similar to welding
> >grade O2 in quality.  Military or medical grade helium is the one to use
> >because the gas is filtered and cylinders are controlled for quality of
> gas.
> >
> >The explosion/fire risk is essentially the same for each grade of O2.  You
> >are probably correct, most welders do not wash their hands, but the risk of
> >fire/explosion from changing an O2 reg with dirty hands is probably nill.
> >O2 is explosive when exposed to hydrocarbons at high pressure, any O2
> >leaking from the reg or bottle valve is immediately reduced to 1atm and
> >diluted in the ambient atmosphere.
> >
> >An interresting anecdote: I am an engineer for a company that designs
> custom
> >test machinery to inspect for leaks in vessiles (gas tanks, evaporator
> >cores, a/c compressors, etc...), we use a technology called Helium Mass
> >Spectrometry, where we fill the test object with helium tracer gas and
> >"look" for heluim outside the test object.  A while back, I was starting up
> >a machine I designed, and I connected a Nitrogen tank to the test object to
> >confirm the machine cycle before introducing the helium which sometimes
> >causes another set of problems.  This time I kept getting what appeared to
> >be minor heluim leaks from the test opject.  After several hours, I
> >determined that the nitrogen tank contained helium gas even though the
> >bottle was the correct paint color to indicate nitrogen.  The most
> important
> >thing to be aware of when buying your own gas for mixing is to know what
> you
> >are getting, and welding grade gasses are not controlled to the same degree
> >that the avation grades are.
> >
> >Russ Nolet
> >
> >----- Original Message -----
> >From: p k <abyss30@ho*.co*>
> >To: <techdiver@aquanaut.com>
> >Sent: Saturday, November 27, 1999 8:05 PM
> >Subject: Isn't oxygen, oxygen?
> >
> >
> >> This question has plagued me for a while.
> >> What is the difference between breathing oxygen and welding oxygen?
> >>
> >> First,I was told that welding O2 had more hydrocarbons contained in
> >> it, BUT isn't the explosion/fire risk the same? How many auto mechanics
> >wash
> >> and dry there hands before changing a regulator on an
> >> oxy-acetylene torch? The second thing I was told is "there is possibly a
> >> higher moisture content", to me that doesn't hold up either because
> oxygen
> >> (commercial grade) will always come in a steel cylinder, if there is any
> >> moisture in there it will rust and pretty quickly I might add. So what's
> >the
> >> deal? Anybody?
> >>
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