CO2 Education

Systems, Gear, & DIY
1

Hello everybody this is my first post at HBA, so hello. That said, I found some good information yesterday about CO2 tanks and filling and figured I would share it. Given I realized that having a good working CO2 tank is not only great for those kegging (and those drunk nights) but also safety plays a role into as well.

Now you are probably wondering why I would make a new post and topic (one I was little board). And two, what I found from reading other posts they had some confusing information on CO2, tanks, filling, etc. So I wanted to clear up some information and open room for discussion.

First, lets break down some differences–aluminum, steel, and trading (renting) tanks.

Long and Short answers.

Aluminum - Great for a inside a refrigerator, might not rust, lighter then steel.
Steel - Can rust when using inside a refrigerator, or freezer heavier then aluminum but last longer.
Trading (renting) Tanks - You get a tank that has been hydro tested, and filled. Might be cheaper in long run given that certain tanks can be costly depending on how much you brew or keg. You might get a tank thats steel, or aluminum when trading in for another.

Hydro Testing / Safety

I’m using the word hydro tested because its important to note; when you receive a tank make sure it was hydro tested for safety reason. Now don’t get me wrong, I’m not saying go out and spend the money for a hydro test to make sure its working safely. I’m only mentioning this–to make you aware of it. At one point I was going down to my local brewshop where they would fill my tank. I realized even though they knew alot about brewing I realized they had no idea about filling or tank safety. Given a rule of thumb every 5 years your tank should be hydro tested and inspected depending on the manufacture (check with your local CO2 company about this given that certain tanks may be 10 years).

Filling

Let me get back to filling. Yesterday I went to my local (different) CO2 shop (as you will) where I live and had my CO2 tank filled with food grade CO2 (yes their is a difference). Moreover, what I found is most companies who fill your tank will leave head in the tank for expansion. This is important because of HEAT. Meaning, if you leave your tank outside of the refrigerator you need that room for expansion. If you place your tank inside the refrigerator you might see your gauge show less then what was filled. This will very depending on temperatures. I will get more into it down below.

Chemical and Physical Properties of CO2

So what is this magical gas that helps us drink our delicious brew?

To test for this gas.  When a lighted splint is inserted into a test tube containing this gas, it is immediately extinguished, as carbon dioxide does not support combustion. Don’t confuse this will carbon monoxide which is deadly.

Carbon dioxide is a colorless gas which, when inhaled at high concentrations, produces a sour taste in the mouth and stinging sensation in the nose and throat.  Carbon dioxide, either as a gas or as dry ice, should be handled only in well ventilated areas. Its density is about 1.5 times that of air. The carbon dioxide molecule (O=C=O) contains two double bonds and has a linear shape. It has no electrical dipole. As it is fully oxidized, it is not very reactive and in particular not flammable. At temperatures below -78oC (-109oF), carbon dioxide condenses into a white solid called dry ice.  Liquid carbon dioxide forms only at pressures above 5.1 atm; at atmospheric pressure, it passes directly between the gaseous and solid phases in a process called sublimation.

Uses of CO2

Carbon dioxide (thanks Joseph Black for finding CO2) is used to produce carbonated soft drinks and soda water. Traditionally, the carbonation in beer and sparkling wine comes about through natural fermentation, but some manufacturers carbonate these beverages artificially using carbon dioxide.

Liquid and solid carbon dioxide are important refrigerants, especially in the food industry, where they are employed during the transportation and storage of frozen foods, and in the medical field, where they are used for transportation and preservation of laboratory specimens.

Ending

Now that you a little more educated on CO2, and safety of it; go out and enjoy your delicious home-brew with this magical gas substance thanks to Joseph Black.

2

You mentioned there is a difference between food grade CO2 and other grades. I have heard this before but never heard an explanation. What is the difference?

3

The price

4

That’s for sure. However, is there an actual difference in the product? Purity, etc?

5

My exchanges from airgas say food grade and I only pay $16 for a 10# exchange.

6

That would be the purity of the gas itself. The more 9’s after the 99.9 the purer and less oxygen it has. Then in turn oxidizes your beer less.

7

Cited from FDA
TITLE 21–FOOD AND DRUGS
CHAPTER I–FOOD AND DRUG ADMINISTRATION
DEPARTMENT OF HEALTH AND HUMAN SERVICES
SUBCHAPTER B–FOOD FOR HUMAN CONSUMPTION (CONTINUED)
PART 184 – DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE

Subpart B–Listing of Specific Substances Affirmed as GRAS

Sec. 184.1240 Carbon dioxide.
(a) Carbon dioxide (empirical formula CO2, CAS Reg. No. 124-38-9) occurs as a colorless, odorless, noncombustible gas at normal temperatures and pressures. The solid form, dry ice, sublimes under atmospheric pressure at a temperature of -78.5 deg. C. Carbon dioxide is prepared as a byproduct of the manufacture of lime during the “burning” of limestone, from the combustion of carbonaceous material, from fermentation processes, and from gases found in certain natural springs and wells.

(b) The ingredient must be of a purity suitable for its intended use.

(c) In accordance with 184.1(b)(1), the ingredient is used in food with no limitations other than current good manufacturing practice. The affirmation of this ingredient as generally recognized as safe (GRAS) as a direct human food ingredient is based upon the following current good manufacturing practice conditions of use:

(1) The ingredient is used as a leavening agent as defined in 170.3(o)(17) of this chapter; a processing aid as defined in 170.3(o)(24) of this chapter; and a propellant, aerating agent, and gas as defined in 170.3(o)(25) of this chapter.

(2) The ingredient is used in food at levels not to exceed current good manufacturing practice.
What they mean is filtered. So food grade.

(d) Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1240

8

FYI brewers have access to a plethora of free research grade co2.  :wink:

9

I took a photo of this chart the last time I was filling up my co2 tanks. Take it however you want.

33931490533_55bd892b5e_c.jpg
33931490533_55bd892b5e_c.jpg800×450 70.9 KB

10

Thanks for the info! This definitely helps clarify the difference. I sometimes wondered why some homebrewers would use paintball gun cartridges or welding gas for their beer. In a general sense does it really matter, outside of cost?

11

It does for me, but maybe not you or vice versa. Much like many things in life!

12

Here is a summary of the the welding grade spec of the American Welding Society (1997) & ANSI at https://pubs.aws.org/Download_PDFS/a5.32-a5.32m-1997PV.pdf.  This standard has been superseded.

-99.8% purity. 
-cylinder has to be evacuated or residual gas tested.
-Look for a label on the cylinder indicating SG-C and presumably AWS A5.32, the name of the standard.

13

I’m very fortunate to have a GREAT local welding supply shop. $15.85 for food-grade CO2 aluminum bottle swap, and yes, they always get you another aluminum bottle. They usually also have manifolds and regulators in stock. I’ve yet to receive any bottle that hasn’t looked decent, not that I care too much mind.

The fact that the folks there are very involved in the local drag strip/dirt track are a bonus, it’s nice to talk cars and beer with them.

14

30 ppm O2! [emoji15]

15

I recently bought a full half-barrel keg of Yuengling. It was disturbing how much it staled over the course of the 6 weeks or so it took to finish the keg.

Those with kegerators than can fit a full keg, comparing a commercial beer in kegs to the same beer in bottles will show you just how much this can matter.

Of course, I leverage this oxidation for my usual low ABV/low carbonation/low FG brews.  8)

16

Food Grade Co2 is filtered and certified for human consumption. Industrial grade Co2 can contain oils. But with that said, since the beverage industry is one of the largest consumers of Co2. Most locations just carry the food grade. But it is always good to ask. If you see an oily film on your beer, check your tank.
Brace the tank well and place a white piece of paper about 4-6 inches from the nozzle.
Open the valve in 3-4 burst. ( Tank should be WELL secured) you will see some moisture on the paper but there should not be any dark or oily residue. If so tell your supplier and make sure you get a newly filled tank.

17

While that difference in purity is small, it can make a difference in the longevity of the beer. Its not just the price.

Use food-grade gas.

18

For my own personal sanity I’ve always used food grade co2. Finding out what the difference is between grades has helped me understand why I should use it. It will also help me to explain to other homebrewers why they should use food grade co2.