There is no single ISO 8573-1 class for blowing out bottles and cans: it is set with the maker of your rinser or filler and, where relevant, with your customers' specifications. In practice, air that touches the inside of a container needs to be dried, then passed through fine filters at the point of use, with particular attention to oil. A K series 4-in-1 compressor provides the base, and point-of-use filtration does the rest.
For all the air needs of a brewery, see our page on compressors for breweries and cideries. Here, we focus on the air that touches the container.
Reading an ISO 8573-1 class
The standard is written as [A:B:C]:
- A, particles: dust, rust, wear residues;
- B, water: measured by the pressure dew point;
- C, oil: liquid, aerosol and vapour, in mg per m³.
The lower the number, the cleaner the air. A class is therefore three figures, one per contaminant, and each is treated with different equipment. Our ISO 8573-1 air quality guide gives the full tables.
Station by station, what the air touches
| Station | What the air touches | Basic treatment |
|---|---|---|
| Valves, cylinders, capper, can seamer | nothing, it stays inside the machine | dried, filtered air from the K series |
| Blowing out empty bottles and cans | the inside of the container | K series, plus fine filters at the station |
| Keg purging | the inside of the keg | K series, plus fine filters at the station |
| Contact with wort or beer | the product | to be defined with the equipment maker |
A useful reminder: to push beer or put a tank under counter-pressure, breweries use CO2 or nitrogen, not air.
Water, letter B
A refrigerated dryer gives a pressure dew point of +3 to +10 °C, which matches water classes 4 to 6. That is enough as long as the air does not pass through an area colder than that dew point. The trap in a brewery is the cold room: if an air line runs through a room at a few degrees, the remaining water can condense there and reach the blowing nozzle. In that case, reroute the line or fit a desiccant dryer, which goes much lower.
Oil, letter C
Our compressors are lubricated. The air-oil separator holds back most of the oil: at the outlet of the K 75, oil content is 3 ppm at most according to its data sheet. For air that touches a container, that is only a starting point:
- a general filter, then a fine filter that holds back oil aerosols;
- for the most sensitive stations, an activated carbon filter that also removes vapours and odours.
Always go from coarse to fine, so the last filter does not saturate too quickly. Our article on fine filters explains the mounting order.
Particles, letter A
Particles come from the intake air and from the network itself. A steel network that has carried humid air for years sheds rust. The fine filter at the station stops these particles just before the nozzle: that is why it is placed as close as possible to the point of use, after the network.
Sizing example
A small canning line, with an empty-can blower and a seamer (indicative figures, replace them with those on your data sheets):
- blower, 6 nozzles at 60 l/min: 360 l/min
- filler and seamer: 300 l/min
- valves and controls: 50 l/min
- total: 710 l/min, or 890 l/min with a 25 % margin
The K 75 delivers 1,100 l/min at 8 bar: it covers this need. The point-of-use fine filter is sized on the blower's flow, here 360 l/min, or 450 l/min with the margin, at network pressure. A filter that is too small costs pressure at the nozzle. If the line grows, the K 110 goes up to 1.7 m³/min.
How to set your class
- List the stations where air touches the container or the product.
- Ask the maker of each machine which ISO 8573-1 class it requires.
- Check your customers' specifications, if they set one.
- Define the air treatment for each station with our technicians: dryer, filters, activated carbon.
- Replace filter elements on schedule. A saturated filter no longer protects.
Install the compressor in a dry room, away from washing areas: our article on the compressor room gives the rules. To go further, send us your list of stations with a quote request: we will suggest the matching air treatment.
For your trade: Compressor for breweries and cideries.