To ensure production uptime when planning a compressed air installation, you must take into account the desired or needed compressed air quality. It is essentially a question of water, oil, and dust contents in compressed air.
Once you know these requirements, you can easily specify an installation that ticks all the boxes for the user. The right mix of air treatment equipment can influence everything, from installation efficiency to cost control, environmental friendliness, and future viability.
Requirements for compressed air quality depend on the application and industry
The compressed air application defines the air quality needed. The content of water, oil, and dust particles in the compressed air decide the quality. For each of these categories, ISO 8573-1 defines classes, which each specify upper limits. How much moisture, aerosols, and foreign particles, the compressed air "tolerates" or how much is allowed varies from industry to industry and within the industry segments from factory to factory. Especially when the compressed air comes into contact with the manufactured product, strict requirements apply.
In any case, the user specifies the class he needs for planning, and you then design the compressed air system accordingly. Important to know: Above a certain size and quantity, foreign particles can impair production, reduce output, deteriorate quality, and raise operating costs. This means that the compressed air must always be treated before it is sent to the consumers - the machines that work with compressed air. Therefore, in addition to the compressors (and/or oxygen or nitrogen generators), you should also include the right equipment for compressed air preparation in every compressed air installation. Our article "Dryers, filters, coolers & Co." explains which device performs which function.
Dryers, filters and oil-water separators ensure the required compressed air quality
The compressed air produced by a compressor always contains more or less impurities of moisture, oil/aerosols and dust particles. On the one hand, the air drawn in is never "clean". On the other hand, due to the design of the compressor, oil can enter the compressed air; this must then be removed. This is the case with oil-lubricated compressors, for example; they need the oil for the compression process.
In order to eliminate all impurities in accordance with the required compressed air quality, the compressor is connected to various components of the so-called compressed air preparation ((link to text 07, "Dryers, filters, coolers & Co.")), which are part of a carefully planned compressed air installation. The most important devices are aftercoolers, dryers (especially refrigeration dryers as well as adsorption dryers), filters (coarse and fine filters, activated carbon filters) and an oil-water separator including condensate drainage.
1. aftercooler,
2. refrigerant dryer,
3. adsorption dryer,
Fourth filter,
5. oil-water separator
Today, by the way, compressors are available which already contain built-in refrigeration or adsorption dryers ex works. This reduces the footprint, your planning and installation costs. You will find more detailed information on the components of compressed air treatment in the article linked here.
Energy efficiency example: Different dryers and controls in summer and winter optimise the energy balance
An important example for your planning: Every compressed air treatment starts with preventing water and the possibility of condensation of humidity in the pipe system. Pipes that are outdoors must not freeze from the inside, and compressed air must not carry moisture into fittings and machines. The compressed air is therefore dried to lower the pressure dew point (the temperature at which the moisture contained in the compressed air would condense). The condensate is collected, separated and disposed of. As the outdoor temperature in local latitudes does not fall below freezing in the summer months - usually from early/mid May to September - some operators use different dryers and settings for summer and winter operation. While a refrigeration dryer that reaches a pressure dew point of +3 °C is sufficient for summer operation, an adsorption dryer can be used in the colder months, with which pressure dew points down to -70 °C can be achieved. Explanations on dryers, filters, aftercoolers and oil-water separators can be found in this article.
