Whether served in a tap room or in a restaurant, the perfect pint is the result of the combination of careful brewing and well-controlled dispensing.
PART TWO – Thoughts on Gas Provisioning for the Perfect Pour
For beer products (and also for soft drinks) the primary gas, of course, is CO2. The secondary component for beer is nitrogen (N2). Depending on your rate of use, gases can be delivered in traditional gas cylinders, manifolded gas cylinders (multiple cylinders connected together), liquid cylinders, or even in bulk (i.e., delivered by truck and pumped into a large, refillable vessel installed onsite).
Gases can be delivered pre-mixed, but normally – for greater flexibility and for cost-effectiveness – separate CO2 and nitrogen supply is recommended. An onsite gas blender – with separate blending “channels” – can be used to provide the correct blend for each brew style. In addition, a gas blender will also make it easy to “dial up” different blends from the same gas sources. The separate channels enable you to send different blends to different containers for the different brew products.
You will usually find that you need a gas blend of about 65-95% of CO2 depending on the style of beer and distance between your keg and pouring faucet. Some beers require far less CO2. For instance, a Guinness gas blend is only 25% CO2. Simply put, using a Guinness blend on an American lager will deliver flat beer; conversely, 75% CO2, if used on Guinness, will deliver nothing but foam.
Brew styles are generally divided into four broad categories:
- Guinness/Nitro – 1.2 volumes of CO2
- Bass/Craft Ale – 2.0 to 2.3 volumes of CO2
- Craft Brew – 2.3 to 2.5 volumes of CO2
- Domestics – 2.5 to 2.8 volumes of CO2
A “volume” of CO2 defines how much CO2 is contained per volume of liquid. If a gas with too little CO2 is contained within a keg of liquid that contains a high volume of CO2, the liquid will “surrender” CO2 to the headspace (air-space) above the liquid, and the delivered beer will be flat.
Final note on over-pressurization. Not only can over-pressurization lead to overcarbonation, but even with high nitrogen content in the gas, too much pressure can cause the beer to flow from the tap faucet at a high flowrate that will cause excessive turbulence, which can cause excessive foaming even when overcarbonation is not the issue!
How MATHESON Can Help
Successful, effective dispensing of a variety of brew styles – alongside carbonated soft drinks and mixers – is not complicated, especially if you have the right gas partner. The Gas Professionals at MATHESON can guide you to a gas provisioning solution that makes sense, enables the best product, and saves you money, too.
