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Oxy/Acetylene safety


#1

Hi All , On the subject of Oxy/Acetylene safety .

Can I please warn you all who don=92t know

You should never ever use grease of any type on equipment using
Oxygen, as it causes an almost instantaneous catalytic reaction
resulting in ignition of the Oxygen and an Explosion.

Whilst serving in the Royal Air Force I was trained as a =91Supplier=92=
;
part of that qualification was the supply of =92 =91Bulk fuels, Liquid=
s
and Gases=92 (including Liquid Oxygen & Liquid Nitrogen) , and as such
I qualified as an instructor in my =91Field=92

I once saw an engineers Ruler dipped in =913 in 1=92 oil so the =91han=
ging
hole=92 filled with a small droplet of oil this was then hung by a
piece of cord in front of an oxygen cylinder approx =BD pint in size,
its valve was then opened =96 the resulting explosion created a crate =
in
the earth approx=91 1ft deep by nearly 4 ft across!!

And yes I do use an Oxy/acetylene torch for some of my large work
(bladesmithing & sculptures).

So folks please take great care

Regards
Wayne Danewood
Dain Studio
Wayne@TheSilverSmithForge.co.uk


#2

Greetings & salutations…

Just wanted to share a very interesting thing I learned in school
today. Our teacher was giving a lecture on setting up the Oxy/Acy
torch, and there happened to be a student who works in the sheet
metal industry (an older fellow; this is a community college). As my
teacher was going through the ‘open the oxygen valve 1/4 turn’ part
(which is EXACTLY what they had told me at my tank place), the
student mentioned that since the oxygen is used at such high
pressures it actually needs to be turned on all the way, and then
closed back 1/4 turn. He explained the reasons in great detail but of
course I can’t relay them all; my teacher was astonished that in all
his years of metalsmithing he’d never ever been told about this.
Don’t know if anyone in Orchidland will dispute this advice, but
thought I’d put it out there.

Best, Jessica who’s trying to stay warm in San Francisco by eating
spicy Thai food for dinner


#3

That sounds right. I just checked the manual that came with my
Smith Oxy/Acetylene regulators, and they say to turn on fuel gas no
more that 1 full turn, and to slowly open the oxygen until the gauge
maxes out, then open it all the way. The back off of a quarter turn
is a safety precaution most people who work with pressurized gas
tanks are taught so that the valve can’t be jammed open to the stop
in such a way that it can’t be turned off quickly.

My toughest thing for dealing with my Little Torch is the fact that
I learned on full sized cutting and welding equipment. I still have
trouble judging the flame on those small tips for various purposes,
but that’s just lack of practice, I suspect.

For leak checking, I favor a liquid called “Big Blue” which is
intended for refrigeration and fuel gasses. It will bubble a very
small leak. Since I stopped doing AC repair on a regular basis, I
suspect that my half gallon bottle will likely last for several
years. I keep a plastic film canister full in with my torch stuff.
You can get the stuff from most HVAC and welding supply houses.

 Ron Charlotte -- Gainesville, FL
 @Ron_Charlotte1 OR afn03234@afn.org

#4

Hi Jessica,

As my teacher was going through the 'open the oxygen valve 1/4
turn' part (which is EXACTLY what they had told me at my tank
place), the student mentioned that since the oxygen is used at
such high pressures it actually needs to be turned on *all the
way*, and then closed back 1/4 turn.

It’s not clear from your post if you’re talking about the valve on
the tank or the torch.

Oxy is stored at about 2,000 PSI in a full tank. The valve on the
tank is a double sealing valve. That means it is sealed when it’s
closed & when it’s ‘fully’ opened. If the valve on an Oxy tank isn’t
fully opened, there’s a very good probability of more oxy leaking
out around the valve stem than will be used by the torch. The
packing used around the valve stem can’t contain the oxy under
2,000 PSI. That’s the reason the valve is opened fully; so it gets
sealed against the ‘open’ valve seat.

The fuel gas, on the other hand, is stored at a much lower pressure.
Therefore a standard single sealing (shut only) valve is used on
fuel gas cylinders. The valve stem packing can contain the gas in an
open valve. Typically the fuel gas tank valve is only opened a 1/4
turn (or something less than a full turn).

If you stop to think about what’s required for a flame, it’s oxy & a
fuel. It’s impossible to get rid of the source of oxy, it’s in the
air all around us. If there’s a undesired fire with a torch & you
want to extinguish it quickly, removing the oxy won’t do it.
Removing the fuel will. That’s one of the reasons for only opening
the valve on the fuel gas tank of a welding combination less than a
full turn. It doesn’t take as long to stop the flow of fuel gas.

Dave


#5
 Oxygen valve needs to be turned on *all the way*, 

The reason the oxygen tank’s valve was to be turned all the way open
is because there is another seal surface on the valve stem’s upper
end . This seal surface closes off and seals the cylinder against
loss of high pressure oxygen passing up the valve stem. I do not
consider this to be anything of a health hazard, however if the valve
stem is loose in the packing, enough oxygen may be lost over the
course of a day so as to be wasteful .

The short answer is if the valve is old and leaks when open, then
open it all the way up. I keep my valve closed until I am ready to
begin the day’s hot work. These valves can be repaired or adjusted.
Just don’t do it yourself.

FOR SAFETY’S SAKE , TURN YOUR HEAD AND SHUT YOUR EYES WHEN YOU OPEN
OXYGEN VALVES.

If it is going to blow up, you will hear it just fine. < Grin > Do
turn your head.

ROBB - Retired Old Baby Boomer


#6
 the student mentioned that since the oxygen is used at such high
pressures it actually needs to be turned on *all the way*, and
then closed back 1/4 turn. 

I was taught that your working pressures are based on the size tube
you are using to weld, and the thickness of the metal being welded.
If you turned the oxygen on that high you have to balance it with a
proportional amount of acetylene, and that shouldn’t exceed 15 psi.
We are talking working pressures, right? My standard for a small
size tube and metal no thicker than 10 gauge is 25psi oxy 5psi
acetylene.

Cindy Leffler
Leffler Jewelry


#7

While we’re on the subject of Oxygen and Acetylene–I seem to
remember someone saying that one should not allow the tanks to
become completely empty before refilling or replacing, and something
about not transporting an empty tank when the temperature outside is
below freezing. Is there any validity to either of these for oxy and
/or
acetelene? Sandra


#8

Re: Oxygen cylinders One thing that has not been mentioned is that
the adjusting screw on the oxygen regulator MUST be turned Out
before opening the tank. Most regulators do not have a built in
check valve. If not screwed out this allows 2000 pound pressure to
slam into the regulator and cause serious harm. Then you can reset
the oxygen pressure to the torch. All industrial oxygen users are
warned
to open the tanks this way.


#9
    I was taught that your working pressures are based on the size
tube you are using to weld, and the thickness of the metal being
welded. If you turned the oxygen on that high you have to balance
it with a proportional amount of acetylene, and that shouldn't
exceed 15 psi. We are talking working pressures, right?  My
standard for a small size tube and metal no thicker than 10 gauge
is 25psi oxy 5psi 

In the case of gas cylinders, “working pressure” is normally
understood to be the max. fill pressure of the cylinder which is
stamped on the side or “neck” of the cylinder near the valve. Fill
pressures are primarily determined by the alloy or material (some
high pressure cylinders are actually made from fiberglass) from which
the cylinder is made, intended use (type of gas) and in some cases,
the size/dimensions of the cylinder. Example: I have an aluminum
compressed air cylinder which is rated for 3200 psi, my steel O2 is
about 2200 psi and the small acetylene tank I use with the Little
Torch is rated for about 200 psi. It is a good idea to be familiar
with these numbers regarding the cylinders and gases you normally use
so you can double check your fills in terms of appropriate fill
pressures and to be aware of losing inordinate amounts of gas
(leaks). Also be aware that some newer cylinders are allowed by law
to be filled 10% over working pressure…so don’t be alarmed if it’s
a little over with a new fill. Pressure will also vary with the temp.
of the cylinder. Cylinder pressure will drop with decreasing
temperature although no gas may have been used. Your gas hasn’t
disappeared it’s just under a little less stress!

There are a lot of other numbers stamped on your cylinder which
signify different things (serial number, manufacturer, hydro test
date). Next time you get a fill, see if one of the techs or sales
people can take a minute to show you what’s what. If they don’t
know…you should be a little concerned…especially if it’s a fill
tech!

Is all that clear is as mud?! ;}

Best to all,
Mike Dibble
Black Horse Design
www.black-horse-design.com


#10
      the student mentioned that since the oxygen is used at such
high pressures it actually needs to be turned on *all the way*, and
then closed back 1/4 turn. I was taught that your working pressures
are based on the size tube you are using to weld, and the thickness
of the metal being welded. If you turned the oxygen on that high
you have to balance it with a proportional amount of acetylene, and
that shouldn't exceed 15 psi. We are talking working pressures,
right?  My standard for a small size tube and metal no thicker than
10 gauge is 25psi oxy 5psi acetylene. 

I think that the confusion here is that a fuel/oxy torch set running
off of two stage regulators has 3 pairs of valves to deal with. The
first, and subject of most of this thread is the valves on the tanks
themselves. These get the 1/4 to 1 turn on fuel and full open on
oxygen. Second, the regulator output pressure is controlled by the
center screw/nut on the regulator body. Finally you have the valves
on the torch body itself. Some regulators have gauges for tank
pressure and outlet pressure, some only have the outlet pressure
gauge (I prefer the dual gauges, it makes running out of Oxy or
fuel, without warning, a little harder to do.

It suddenly occurred to me that the terminology was getting
confusing

Ron Charlotte – Gainesville, FL
@Ron_Charlotte1 OR afn03234@afn.org


#11
    Re: Oxygen cylinders One thing that has not been mentioned is
that the adjusting screw on the oxygen regulator MUST be turned Out
before opening the tank. 

Good point, that’s one of those muscle memory things you forget to
mention when you’ve done it often enough. I habitually back my
regulators out when I shut down, especially if I’m going to
transport the gear.

Ron Charlotte – Gainesville, FL
@Ron_Charlotte1 OR afn03234@afn.org