# Food grade Co2



## Canoe2Can (Oct 31, 2004)

I'm confused. What is food grade CO2? Never even heard of such a thing. CO2 is just two oxygens bonded to a carbon atom. There's nothing about it to be food grade.


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## Momotaro (Feb 21, 2003)

I have heard of different grades of CO2. Medical, food and welding. What are the differences? I don't know!  Like Canoe2Can, I don't see the how they manage to create the grades.

Don't worry, Barbels. What you have is just fine! 

Mike


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## Canoe2Can (Oct 31, 2004)

Here's a thought, maybe different grades have different purities. Makes sense that it would be difficult to have perfectly pure CO2. Maybe medical grade is the purest, then food, then welding. Makes me wonder what else I might be pumping into the tank.

But the fish aren't dead yet... so back to Greco Gas and Welding Supply I go!


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## Momotaro (Feb 21, 2003)

I believe you are right, but I am not sure how they purify the gas.

I believe welding grade is fine for our application.

Mike


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## briandmiles (Feb 23, 2005)

I doubt there is any difference beside the name of the grade. I'm in dental school and I can tell that things I buy for dentistry cost ten times as much as the exact item not packaged for dentistry. It's a joke but what can you do? Buy Welding Grade! That's what.

Brian


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## bharada (Mar 5, 2004)

From a home brewers site.



> Grades of CO2
> 
> There have been a number of questions regarding "Is all CO2 created
> equal?"
> ...


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## freeflyer (Feb 3, 2005)

With somethings they charge more as a liability charge, its the same product but they have to carry extra insurance for selling it as medical grade. So they just have the people who are using the products for these purposes cover the cost rather than making everybody pay. Its the same in aviation everything costs more because of the added liability. I dont know for sure if thats the case here or if it really is more highly purified


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## Rolo (Dec 10, 2003)

Barbels said:


> What are the disadvantages to using regular welding-supply store :icon_roll Co2? Is it dangerous? Is it icky? What?


Nope, it is definately pure and safe enough for our needs. Industrial grade (the lowest) from where I got my CO2 has to be a minimum of 99.99% pure. Any higher grades gets you 1 or a few more 9's, which isn't necessary for us.

That's some very helpful info, bharada. roud:


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## bigfishy (Dec 31, 2004)

The first fill I had resulted in a lot of bubbles within my reactor. In hindsight, I now suspect that there was a lot of air within the tank before it was filled with CO2. Air (consisting of nitrogen and oxygen) would be considered an impurity. If there were oxygen in a tank that was pumping beer (the best food) then it would result in oxidation of the beer and a foul taste.

I suspect this is what is meant by "food grade" CO2.

Incidentally, since I returned my tank and they emptied it completely then refilled I haven't had any problems of bubbles inside my reactor.


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