A member outreach initiative of the Brewers Association Technical Committee

Carbonation Demystified: Carbonation Basics, Natural Carbonation

and the CO2 Supply

I. The Basics of Carbonation -Dave Meheen, President, Meheen Manufacturing

II. Principles of Natural CarbonationMarty Velas, Director of Brewing Operations, Smoky Mountain Breweries

III. CO2 Supply Chain and PurityJim Tomczyk, Purification, Dehydration and Filtration Market Development Manager, Parker –domnick hunter

Carbonation: The Basics

Dave Meheen

Understanding Beer Carbonation• How Carbonation Effects Beer

• Presentation• Mouthfeel• Taste/Smell

• What are CO2 Volumes• Determining CO2 Volumes• Effect of Temperature on CO2 Absorption• Carbonating stones

• Types• Wetting Pressure

• Operating Carbonating Stones• Calculating Pressure and Flow Rates

What Are CO2 Volumes

Beer @ 35° F 10 PSI

2.5Volumes

CO2 CO2

CO2

Beer w/o CO2

• CO2 is very soluble in beer:o solubility increases with increasing pressure; o solubility decreases with increasing temperature

• In the US, the amount of CO2 in beer is most often referred to in terms of “volumes” (defined as the volume the CO2 gas would occupy at atmospheric pressure and 0° C if it were removed from the beer)

• Most packaged beers are considered normally carbonated with 2.45 to 2.85 volumes of dissolved CO2

Henry’s Law Video: http://www.youtube.com/watch?v=8yU5y-cFXoo

Determining CO2 Volumes

• CO2 volumes in beer are determined by physical laws• The solubility of CO2 in beer depends on the temperature and

pressure conditions of the beer and gas at equilibrium conditions,meaning the same amount of CO2 is diffusing out of the beer as isbeing dissolved back into solution

Ø It is critical that the readings used for determining CO2 volumes aretaken under equilibrium conditions, and the instruments used areaccurate

Carbonated Beer

CO2

ZahmGehaltemeter

Carbonation Level Reference Chart

325 N. Oregon Ave., Pasco, WA 99301(509) 547-7029 Fax (509) 547-0939Web @ http://www.meheen-mfg.com

Inc.

Beer carbonation at various temperatures and pressures Pounds per Square Inch

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 30 2.23 2.36 2.48 2.60 2.70 2.82 2.93 3.02 31 2.20 2.31 2.42 2.54 2.65 2.76 2.86 2.96 32 2.15 2.27 2.38 2.48 2.59 2.70 2.80 2.90 3.00 3.11 3.21 33 2.10 2.23 2.33 2.43 2.53 2.63 2.74 2.84 2.96 3.06 3.15 3.25 34 2.06 2.18 2.28 2.38 2.48 2.58 2.69 2.79 2.90 3.00 3.09 3.19 35 2.02 2.14 2.24 2.34 2.43 2.52 2.63 2.73 2.83 2.93 3.02 3.12 3.22 36 1.98 2.09 2.19 2.29 2.38 2.47 2.57 2.67 2.77 2.86 2.96 3.05 3.15 3.24 37 1.94 2.04 2.14 2.24 2.33 2.42 2.52 2.62 2.71 2.80 2.90 3.00 3.09 3.18 3.27 38 1.90 2.00 2.10 2.20 2.29 2.38 2.48 2.57 2.66 2.75 2.85 2.94 3.03 3.12 3.21 39 1.86 1.96 2.06 2.15 2.25 2.34 2.43 2.52 2.61 2.70 2.80 2.89 2.98 3.07 3.16 3.25 40 1.83 1.92 2.01 2.10 2.20 2.30 2.39 2.47 2.56 2.65 2.75 2.84 2.93 3.01 3.10 3.19 3.28 41 1.79 1.88 1.97 2.06 2.16 2.25 2.34 2.43 2.52 2.60 2.70 2.79 2.88 2.96 3.05 3.14 3.23 42 1.75 1.85 1.94 2.02 2.12 2.21 2.30 2.39 2.48 2.56 2.65 2.74 2.83 2.91 3.00 3.09 3.18 3.26 43 1.72 1.81 1.90 1.99 2.08 2.17 2.26 2.34 2.43 2.52 2.61 2.69 2.78 2.86 2.95 3.04 3.13 3.21 44 1.69 1.78 1.87 1.95 2.04 2.13 2.22 2.30 2.39 2.47 2.56 2.64 2.73 2.81 2.90 2.99 3.07 3.16 3.24 45 1.66 1.75 1.84 1.91 2.00 2.08 2.17 2.26 2.34 2.42 2.51 2.60 2.69 2.77 2.86 2.94 3.02 3.11 3.19 46 1.62 1.71 1.80 1.88 1.96 2.04 2.13 2.22 2.30 2.38 2.47 2.55 2.64 2.72 2.81 2.89 2.98 3.06 3.15 3.23 47 1.59 1.68 1.76 1.84 1.92 2.00 2.09 2.18 2.26 2.34 2.42 2.50 2.59 2.67 276 2.84 2.93 3.02 3.09 3.18 48 1.56 1.65 1.73 1.81 1.89 1.96 2.05 2.14 2.22 2.30 2.38 2.46 2.54 2.62 2.71 2.79 2.88 2.96 3.04 3.13 49 1.53 1.62 1.70 1.79 1.86 1.93 2.01 2.10 2.18 2.25 2.34 2.42 2.50 2.58 2.67 2.75 2.83 2.91 3.00 3.07 3.15 50 1.50 1.59 1.66 1.74 1.82 1.90 1.98 2.06 2.14 2.21 2.30 2.38 2.46 2.54 2.62 2.70 2.78 2.86 2.94 3.02 3.10 51 1.57 1.64 1.71 1.79 1.87 1.95 2.02 2.10 2.18 2.26 2.34 2.42 2.49 2.57 2.65 2.74 2.82 2.90 2.97 3.05 52 1.54 1.61 1.68 1.76 1.84 1.92 1.99 2.06 2.14 2.22 2.30 2.38 2.45 2.53 2.61 2.68 2.76 2.84 2.92 3.00 53 1.51 1.59 1.66 1.74 1.81 1.89 1.96 2.03 2.10 2.18 2.26 2.34 2.41 2.49 2.57 2.64 2.71 2.79 2.86 2.94 54 1.56 1.63 1.71 1.78 1.86 1.93 2.00 2.07 2.15 2.22 2.30 2.37 2.45 2.52 2.59 2.66 2.74 2.81 2.89 55 1.53 1.60 1.68 1.75 1.82 1.89 1.97 2.04 2.12 2.19 2.26 2.33 2.40 2.47 2.54 2.62 2.69 2.76 2.83 56 1.50 1.57 1.65 1.72 1.79 1.86 1.93 2.00 2.08 2.15 2.22 2.29 2.36 2.43 2.50 2.57 2.64 2.71 2.78 57 1.54 1.62 1.70 1.77 1.83 1.90 1.97 2.04 2.11 2.18 2.25 2.32 2.39 2.46 2.53 2.60 2.66 2.73 58 1.51 1.59 1.67 1.74 1.80 1.87 1.94 2.01 2.08 2.15 2.21 2.28 2.35 2.42 2.48 2.55 2.62 2.69

To use this chart: First find the beer temperature along the left hand vertical edge. Then read the pressure across the top and where the two cross, read the volumes of CO2.

CO2 Pressure Temperature Volumes Chart, information about carbonation and partial pressures can be found in the Draught Beer Quality Manual:

www.DraughtQuality.org, Appendices B&C

Carbonation Level Reference Chart

• The values in this table assume sea-level altitude, beer specific gravity of 1.015, and beer alcohol content at 3.8% abw or 4.8% abv. Values shown are in psig, or gauge pressure

• It’s important to remember that carbonation is proportional to absolute pressure, not gauge pressure. Atmospheric pressure drops as elevation goes up. Therefore, the gauge pressure needed to achieve proper carbonation at elevations above sea level must be increased. Add 1 psi for every 2,000 feet above sea level

• For example, a retailer at sea level would use 11.3 psi gauge pressure to maintain 2.5 volumes of CO2 in beer served at 38º F. That same retailer would need 13.3 psi gauge pressure at 4,000 feet elevation to maintain 2.5 volumes of CO2

• For best results when using force carbonation in a tank, the beer should be as cold as possible, ideally 30°-32° F.

Ø CO2 gas solubility increases as beer liquid temperature decreases

Ø CO2 gas solubility decreases as beer liquid temperature increases

v Therefore, the colder the beer, the more readily CO2 is absorbed into solution. This results in quicker carbonation and more efficient use of CO2.

• For example, 10 psi CO2:

Ø 33o F gives ~2.6 volumes CO2

Ø 40o F only ~2.3 volumes CO2

Effect of Temperature On Carbonation

• Carbonating stones increase the surface area contact with the beer by producing tiny bubbles of CO2 which dissolve more readily in beer than bigger bubbles.

• Carbonating stones are generally made of porous stainless steel or ceramic. Both work well for producing curtains of tiny bubbles which are readily absorbed into cold beer.

Carbonating Stone Types

Carbonating Stone Operating2 psi

Tiny Bubbles Video on YouTube: http://www.youtube.com/watch?v=1zUzOwPLMas

Carbonating Stone Operating5 psi

Tiny Bubbles Video on YouTube: http://www.youtube.com/watch?v=1zUzOwPLMas

• All carbonating stones, regardless of type, have what is known as a “wetting pressure”

• The wetting pressure is the amount of pressure required for the CO2 to pass through the pores of the carbonating stone and begin to make bubbles

• Wetting pressures are, generally speaking, between 2-8 psi

• Ceramic stones typically have higher wetting pressures than stainless steel

• Knowing the pressure required for each stone to begin making bubbles is important as well as the pressure when the bubbles will stop. Not all stones are created equal – “your mileage may vary”

• Important: excessive pressure often will cause a stone to be ineffective at making small bubbles. More later…

Carbonating Stone Wetting Pressure

Critical points for carbonation:

• Clean carbonating stone making tiny bubbles

• Tank not overfilled, with 15-20% head space

• Cooling system is up to the task = Cold beer

• But, glycol not too cold (28 oF minimum to prevent freezing of beer in tank and uneven carbonation)

Operating Carbonating Stones

Operating Carbonating StonesCalibrating your stone:

• Connect the carbonation stone with its holder to a CO2 bottle with good quality regulator and gauge

• Place the stone in a bucket of water with the stone submerged and in its orientation the same as it will be installed in the tank

• Slowly increase the pressure until a curtain of fine bubbles forms and record the gauge pressure (psi)

• Next slowly decrease the pressure until the bubbles stop and record that gauge pressure (psi). These pressures can be used to help with diagnosing carbonation issues.

• ** If you see any leakage of gas from around the holder, correct the leak and repeat this test.

• Next with the stone still in the bucket of water, turn the CO2 pressure to 30 psi and observe the bubbles. If the bubbles are excessively large or the curtain of tiny bubbles is lost, too much CO2 is passing through the stone. To correct this, a small adjustable needle valve can be installed in the CO2 line prior to the stone. Adjust the needle valve down until you observe a correct curtain of tiny bubbles from the stone.

Effect of Beer Static Pressure:

• Every 28” of beer liquid height adds 1 psi of pressure on the stone

• In the example to the left the liquid height is 84” above our stone

• Therefore, 84”÷ 28”= 3 psi

• So for example, for a stone with 5 psi wetting pressure to carbonate this tank, you would need to add the 3 psi liquid pressure + 5 psi wetting pressure. 8 psi is required from the CO2 regulator for the stone to start producing bubbles

• Assume a target of 2.58 volumes in the beer at 34°F. From the chart the equilibrium pressure in the head space of the tank when carbonation is complete will be 10 psi

• Therefore, if all is ideal the CO2 pressure needed at the stone is the wetting pressure (5 psi) + liquid head pressure (3 psi) + the final equilibrium pressure (10 psi) = 18 psi

Operating Carbonating Stones

It is desirable at the beginning of the carbonating process to use a relatively low differential pressure between the stone and the head space in the tank while bleeding gas from the top of the tank.

Ø This can scrub unwanted dissolved air out of the beer picked up during transfer, filtration or the brewing process

o Be especially careful not to over do this: too much CO2 scrubbed through the beer can cause foaming in the tank and strip away the desirable nose from the beer.

Operating Carbonating Stones

In an ideal world all of the CO2 from the stone would be absorbed into the beer; but things are rarely ideal, so just because you have 10 psi in the head space, doesn’t necessarily mean you have 2.58 volumes in the beer

• Each tank should be tested during carbonation to ensure proper carbonation levels with high quality calibrated gauges on your tester

• Beer carbonation using a stone can take a few hours to several days

• Best results achieved using a relatively slow step carbonation process which tends to yield smaller bubbles and better head retention than rapid carbonation by agitation. Step carbonation refers to adding gas slowly and ensuring the carbonation stone always makes a curtain of tiny bubbles. So you might start your carbonation process at ½-1psi above the total wetting pressure of the stone and leave it at that pressure for a period of time, then increase the pressure in small increments every ½ hour or so.

• Agitation is caused by turning the pressure to the stone on full blast and forcing large amounts of CO2 through the beer. Agitation allows much of the CO2 to bypass being absorbed into the beer and can cause:

o foaming inside the tank;

o loss of nose;

o diminished quality of the finished beer;

o difficulty obtaining consistent results regarding desired volumes even with regular testing.

• There are commercial solution such as the Meheen Tank Manager which duplicate manual step carbonation, freeing up your time and yielding better consistency

Operating Carbonating Stones

Q & A

Thank You to Our Presenters:Dave MeheenMarty Velas

Jim Tomczyk

This presentation, including an audio transcript and complete Q&A, will be available soon in the Power Hour archive of the Members-Only section of

BrewersAssociation.Org. Register today!