You can not serve a quality draft beer unless you are using the proper gas system.
Gas is used to propel the product from the barrel to the point of dispense. The pour pressure is used to set the pour speed (2oz. per second). The gas is also used to maintain the carbonation level in the product to the specifications the brewer intended.
Most service calls regarding beer not pouring are due to an empty or closed (shut-off) gas supply tank.
Gas Draft Beer System Type
The following are explanations of gas system types. All beer systems have a set of parameters that will dictate which type of gas system can be used. All carbonated fluids use a combination of temperature and pressure to keep the gas in solution ( bubble in the fluid ).
100% Co2 Draft Beer System
This gas will typically be found on direct draw or very short air shaft/remote cooled systems. Co2 is a gas that naturally occurs during the brewing process. When you receive a barrel of beer it will naturally have between 10 and 14 Psi @ 38 Deg. F. If you were to apply more than 14 Psi to a barrel of beer you would cause the fluid to absorb more Co2 than was intended by the brewer and more than the liquid can hold. Essentially you have over carbonated the beer; this will cause foaming and waste.
Mixed/Blended Gas Draft Beer System
This type of system is determined per system parameters and by application. If either the system parameters require more than 15 Psi to be introduced to the barrel or the application specifically calls for it, nitrogen (N2) must be blended with Co2 to prevent the product from over carbonating. Although you can custom order a blending device with specific outlet blends, with the ever changing number of beers on the market the standard dual outlet blender will handle most system requirements. A standard dual outlet blender would make two outlet blends: 60% Co2 / 40% N2 and 75% N2 / 25% Co2. This can be achieved in a couple of different ways.
- N2/Co2 blending device: A gas blender being supplied by a cylinder of N2 and either a cylinder of Co2 or a bulk Co2 vessel to achieve its mixed gas blend.
- Nitrogen Generator System: This system uses an air compressor and a wicking device to create a nitrogenated air supply (99.7% N2). This gas will then enter a N2/Co2 Blender along with Co2 from either a cylinder or bulk Co2 vessel to achieve its mixed gas blend.
Beer Pump Draft Beer System
This system uses a gas powered pump similar to a soda BIB pump to propel the product from the barrel to the point of dispense. 100% Co2 would be introduced to the barrel at 10-15 Psi to maintain carbonation. A higher pressure of Co2 would then be applied to the beer pump, per the system parameters, to achieve the targeted pour speed of 2oz. per second.
Beer Gas Draft Beer System
Beer gas as it is most commonly referred to be a pre-mixed gas cylinder containing 75% N2 and 25% Co2. This gas is also known as stout gas or Guinness gas; it is intended for nitrogenated products only! If this gas is used on carbonated beers it will result in flatness and waste.
Air Compressor/Co2 Blending Draft Beer System
This system is obsolete. Air compressors introduce oxygen and other contaminates to the beer barrel leading to off tastes, flatness, over carbonation and gas system failure.