Brewers strive to keep their brewery as clean as possible and prevent unwanted contamination of the product and their equipment. All equipment that comes into contact with wort or beer is cleaned, sanitized, and stored in a sanitary manner. What no one ever considers is the air that touches their kegs, fermenters, and other equipment. Your air compressor is probably one of the first pieces of machinery your brewery had and compressed air is used everywhere. From supplying air to canning and bottling lines, moving valves and actuators in your brewhouse, or purging kegs during washing, compressed air is vital to day-to-day brewery operations.
Air Compressors In The Brewery
What about the compressors themselves? Most people will buy what they need without actually thinking about what is best for their application and what air quality breweries should use. There are three common types of air compressor, split into two categories: oil-lubricated and oil-free/less. The three types are:
Piston:The standard workhorse of a compressor. You’ll hear these before you see them and they can be quite loud if you’re working around them for any length of time. Typically, oil-lubricated but can be oil-free. Pistons have the highest standard working pressure of all three types, commonly around 175 PSI. They are also the most affordable and cheapest to maintain. The drawback is noise level and their tendency to produce hot air saturated with contamination (water and oil). When properly maintained and treated, a piston can produce high quality air, they just need have more attention paid to them. The duty cycle (how often it is on and making air vs off and not producing anything) should not exceed 75% and the compressor should be allowed time to cool down between uses.
Scroll: Often much quieter than a piston compressor, a scroll compressor is also oil-less. This eliminates the possibility of oil contamination passing downstream and allows you to make air with peace of mind. These are also rated at a 75% duty cycle and will have low maintenance, the only thing you’ll need to remember is that the tip seals of the scroll will need to be maintained every 10,000 hours or so. The peace of mind of a scroll comes with drawbacks though. Due to the oil-less scroll you will only get a max pressure of 116 PSIG and your CFM (cubic feet per minute, or volume of air delivered) will be less than a piston or screw compressor of similar size.
Rotary Screw: The last most common type of compressor found in breweries is a rotary screw compressor. Another type of technology, this kind of compressor is made to run 100% of the time. Highly efficient and engineered, a rotary screw compressor can run fully loaded for years when maintained properly. This level of efficiency and reliability comes with a higher price tag though. They also need to be sized correctly for the application they are going into, you should not oversize them by too much. Pressure will cap out at 125 or 160 PSIG as standard, but can be set as low as 90 PSIG.
In the next blog post we will discuss filtration and air treatment in a brewery application.