Outside my building there was a Airgas truck filling a small tank from a larger “Medical Nitrogen” tank. There were also tanks of oxygen and I’m guessing helium , acetylene, etc. There was also a tank just marked “Nitrogen”
I’m not sure why the building across the street would need nitrogen (medical or not) unless it is part of the Kaplan University nursing program.
Anyhow, my question is - what is the difference between normal and medical nitrogen? I’m guessing it is quality control / labeling / chain of custody type thing perhaps with a guaranteed purity component.
Yes, I would guess that medical/human use N2 is guaranteed purity. The kind used for industrial processes might not be completely free of contaminants harmful to humans breathing it.
Might be used in labs to provide a dry, absolutely neutral gas for some kinds of tests. Possibly used to make “perfect,” pure N/O2 mixes for sensitive patients.
It’s used by telecomm and other industries to slowly blow moisture out of wiring runs as well.
Actually medical grade Nitrogen is of lower purity than many of the industrial grade nitrogen specs (99% versus 99.99%+)
The difference is in the pressure. Medical grade nitrogen is supplied with higher pressure for pneumatic tools and I beleive for some lasers (not sure though).
I watched a guy drilling a hole into a 4" gas pipe once. I asked his mate how they could do that without blowing us all to kingdom come, and he told me that they filled the section of pipe they needed with nitrogen. I imagine that it didn’t need to be all that pure.
They put it in tyres, and it is also used in food packaging.
When I was a lab tech, I bought medical grade CO2 from Airgas. I asked about the differences between the medical grade and “regular” CO2. I was told the gas itself was the same but the cylinder had coatings to prevent contamination (maybe teflon?).
Years ago I asked a relative who worked in the business about this. He said it’s all pumped from the same tank into the same cylinders. The difference is that after pumping they test each cylinder of medical gas individually. For the industrial gas they just choose a couple cylinders from each batch to test.
It’s for the same reason you shouldn’t eat pet food or road salt.
They are the same ingredients and technically edible but not manufactured, transported or packaged to human consumption standards.
Ok, this makes sense, medical use but not for direct human-respiration. Because I couldn’t understand why it would be necessary to make ‘pure’ air with Oxygen & Nitrogen cylinders. Seems like it would be much simpler & cheaper to just use a good filtration system on regular air…
The most likely contaminant of nitrogen gas would presumably be oxygen gas. Not only are they found together in air, but they condense at about the same temperature. (though, as liquids they mostly separate and the blue oxygen rises to the top.)
I don’t have a cite, but I can tell you that for a lot of industrial purposes 0.1% oxygen mixed with ‘pure’ nitrogen would be a disaster. There are a lot of things that don’t react with nitrogen that will react with oxygen.
I can’t think of a medical purpose offhand where a tiny amount of oxygen would be a problem, but I don’t really know medicine so such may exist. To add to am77494’s examples, I know that MRI machines go through lots of liquid N2 every day for cryogenics, and I doubt for that purpose a tiny impurity would matter much.
There are lot of misunderstandings in this thread. Some are thinking Nitrogen as Oxygen - others as CO2. As a Chemical Engineer who has worked in this area, I wish I had the time to write a detailed post with purities, pressures and temperatures of each grade of Nitrogen.
For Starters, beowuff, here is a cite from Air products - which is in the league of Air-Liquide /Linde/ Praxair. Some of the world’s largest air separation plants are made by Air-Products.
Quote from cite:
Look in the middle of the page
Nitrogen
Nitrogen and trace inerts 99.998%
Oxygen Less than 0.001%
Dew Point Liquid Nitrogen: -90ºF or lower
**
Medical Nitrogen** – meets Nitrogen NF
Nitrogen and trace inerts 99.0%
Oxygen Not more than 1.0%
Carbon Monoxide Less than 0.001%
Odor None
For MRI’s you need liquid helium. Liquid helium is kept liquid by surrounding it with Liquid Nitrogen in a clever arrangement so that Nitrogen evaporates and Helium does not (at least minimally) - Helium is very expensive now. Thats another thread though
Yeah, the insulated jar containing the helium is encapsulated by an insulated jar containing liquid nitrogen, to minimize the amount of environmental heat that gets to the central helium. The helium details are outside the scope of the thread, but suffice it to say they go through a lot of liquid nitrogen daily to do this.