welding oxygen breath?

i was wondering if it’s safe to breathe the oxygen tanks you find in hardware stores. the reason i ask is that when you see stores that sell oxygen cylinders for medical supply companies, they dont come filled and they always say you can fill them for $5. i’m assuming that for such a cheap price, it has to be the same place that would fill tanks that would be used in welding.

aside from that, let’s say they are safe to breathe. what health problems would i see besides nausea, passing out, and pneumonia?

Good article on breathing welders oxygen here:

That article, although it mentions the dangers of handling compressed gases, doesn’t seem to say very much about the potential health risks of breathing pure oxygen (oxygen toxicity, lung damage), nor indeed the greatly increased risks of catastrophic fire (anything that merely smoulders in normal air will flare up and burn quite violently in pure oxygen.

The first part of his question was asking about the different types of oxygen (medical and welding), and which is safe to breathe. That article addresses his question, along with the fire hazard.

Hmmm, I still have reservations; the whole thing seems (to me) to be written from the “hey, let’s go breathe some oxygen, now!” angle. He doesn’t mention oxygen toxicity, the only health aspect he seems to mention (unless I’m missing one) is that breathing dry gases is bad for your lungs (and I seem to recall hearing that debunked somewhere recently)

      • If you search, you’ll find this question asked and answered–somebody answered that medical-grade oxygen is only a bit more pure than welding oxygen, and the general observation was that welding oxygen could only possibly contain small quantities of innert gas, as anything combustable (non-innert) would ignite when under that much pressure at room temperature in pure oxygen. The welding shop I asked said that acetylene can blow vapor through the lines if the tank is upset, but that “pure” welding gas (such as oxygen, nitrogen, hydrogen, helium, argon, etc) is typically over 99.9% pure anyway.
  • Also though I note that my mom has to occasionally use oxygen now, and she was told and has found that the tanks leak out in only a couple weeks even if left unused. The welding tanks I have on hand have been half-empty for several months now–so apparently there’s some difference in the tank valves of welding vs. medical gas tanks also.

The oxygen may be the same going in the tank but it is not the same coming out. Breathing oxygen tanks are manufactured without any oils use in the process and the tanks are usually lined to prevent corrosion, oxygen is also a corrosive. No oils are used in the fittings and gauges nor in the assembly of a tank. Welding oxygen tanks are not lined and most are rusty. There are also the possibility of other contaminants in the tank and fittings. Small amounts of oils when pressurized in a larger vessel will vaporize. Breathing vaporized oils over time will do nasty things to your lungs. Places that fill both types of tanks do not use the same tap from the LOX tanks. The welding tanks are filled in the same area as the other tanks, breathing tanks are filled in clean rooms or booths. It is the cost of maintain a facility capable of filling breathing oxygen tanks is the reason for the price differences between breathing and welding oxygen. I am certified for the installation of breathing oxygen systems on Boeing aircraft, even the tools we use to assemble the oxygen systems are cleaned and bagged for us prior to use. Drop a wrench on the floor, you go the the tool room and get another. Personally, I would not find welding oxygen to be an acceptable substitute for breathing oxygen.

      • Umm…welllllll… Both types of oxygen tanks would have to use clean, non-rusty tanks, for exactly the same reasons: oil will combust in 3000 PSI oxygen no matter which tank it was in (many oils will combust in 3000 PSI atmospheric air mix).
  • This internal-tank-coating business I don’t know about, but images I have seen of burst welding and NOS tanks show the insides to be clean silver, free of any rust or surface damage. And when gas welding, you’re not supposed to run the oxygen tank completely out, in order to prevent moist air from entering and corroding it … The price difference you mention is more than likely simple liability charges–sellers if medical supplies probably get sued more often than welding shops do.

Welding gas purity:
Medical gas purity:
-I can’t find any online sources–only sites that sell “laboratory” and “research” gasses with the same purities available as welding gasses. Many go into the detail of the mixes, but none seem to mention the overall purity…???