Hey Thomas, I would like to add to what Robert has said. My Father, John L Emmerson, was the chief Toxicologist at Eli Lilly for many years. I asked him about using reagent grade supplies, some with 6 - 9's purity (99.9999%), and his reply was eye opening. He said that indeed the purity was higher, but the methods with which that purity is obtained are definitely not food grade. For example, reagent grade Ethanol uses Benzene in its process. He said it is best to buy only food grade supplies for safety and traceability.
Original Message:
Sent: 08-22-2025 05:46
From: Robert Bernier
Subject: Is it an obligation to use food grade certified compressed oxygen (gas) for product contact?
Hello Thomas-
I worked for a gas company for over 20 years, retiring in 2019. Your question has come up many times and the answer to your questions can vary. There are several "Food Act" legislative bills that have been approved since the original in 1938. Let me explain the intention of the FDA guidelines, as I remember them. I would encourage you to contact the company that actually fills the cylinders you use for more detail (the company name will be on the cylinder label located on the shoulder of the cylinder).
First, the "grades" of gases are important to the end user, because the gas cylinders are only used in that industry to prevent any chance of cross contamination. Food grade, medical grade and industrial grade have their own environments that may be detrimental to the others. Example: Medical cylinders could have blood borne pathogens on them. Or worse, someone could have left a valve open on an empty cylinder, and some impurity found its way into the cylinder. Normal cylinder filling practices include a cylinder vacuum to remove any residue. This FDA rule helps prevent any cross contamination of the cylinders from different end user types. Also, Food Grade, Medical grade and other specific grades, like UHP, have lot numbers on the cylinders for tracking and analysis. Each lot has test results for that particular grouping of cylinders filled with that particular gas, from that particular cylinder filling manifold. Those results are available from the gas cylinder filling location, sometimes for an additional cost.
Then there are the gas purification standards. These standards detail what purity minimums are needed of the gas and what the maximum amount of any impurities that can be in the gas. These standards must be proved through testing at the gas cylinder filling site where the purification standards are available to the end user, sometimes at an added cost. I do not have any updated details on the purification of Oxygen, but my past notes show that the minimum standard in 2017 was 99.0% for Medical Grade and 99.2% for Food Grade. And yes, the gas is likely to come from the same bulk storage tank at the gas filling location and filled into different grades of cylinders. That is common practice and usually results in better purity of the gas in all grades filled at that gas filling location.
Regarding Ultra High Purity Oxygen (UHP) Gas being certified as Food Grade- not likely. Refer back to the cylinder standards and the gas cylinder filling company most likely is not allowed to put UHP gas into a Food Grade Cylinder. I am not certain that there are restrictions for you using UHP in your application. That answer would come from the gas cylinder filling company.
Your best source for the answers to your questions is the company that actually fills the gas cylinders. They are responsible to use the correct cylinder and prove the purity and impurities of each lot of cylinders that are filled. I hope my limited insight helps you make the best decision for you.
Best Regards,
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Bob Bernier
Retired from Matheson Gas
Auburn, ME
207-740-8256
Original Message:
Sent: 08-21-2025 09:55
From: Thomas Sjoberg
Subject: Is it an obligation to use food grade certified compressed oxygen (gas) for product contact?
The title of my post may cause you to think "what's this guy thinking" but it is complicated. At least it seems so for the state of Georgia but it could be a national "issue". I'm new to the country, I work as a head brewer and I found out our bottle of oxygen which ran out (after 8 years => 125 cu feet cylinder) wasn't food certified. After forcefully doing research because our original supplier isn't able to help by provide us food grade oxygen I come to find out different things of interest.
1)Food grade Oxygen isn't a very high purity oxygen (everything relative of course) and is actually industrial grade that is being certified for food use. Highly carcinogenic compounds such as hydrocarbons are higher than many other grades of oxygen.
2) It seems impossible to food certify oxygen grades other than industrial.
3) Industrial grade oxygen in compressed gas is mostly only available from/starting with 200 Cu feet cylinder => that size cylinder would last us close to 15 years for our size production.
4) I haven't been able to find out yet (although I'm trying to contact the FDA about this) if UHP ULTRA HIGH PURITY which is very common in all size cylinders and purer than food grade oxygen, can actually be legally used. UHP oxygen is much easier to get in smaller cylinder and would actually be better to use and cost isn't prohibitive.
Do my 3 questions are:
1) Does food grade certification needs to be a requirement even if using purer oxygen than the industrial oxygen certified as food grade?
2) Can all grades or UHP be food certified?
3) Can I use UHP even if not food certified?
4) If I cannot get 80 cu foot of regular UHP oxygen, can I get that size cylinder of UHP that is food certified.
Not so easy...
Thanks for any feedback!
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Thomas Sjoberg
Head Brewer
Hopstix
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