Which dryer,
which filtration.
The choice is not made on a standard, it is made on what your air will touch. Four uses, four chains, and for each one what it does not cover.
Workshop air
Air tools, blowing, cylinders, tightening, handling. The air touches neither the product nor its surface.
Pressure dew point +2 to +10 °C depending on the model, which is water class 4 to 6 under ISO 8573-1. The air no longer condenses in a heated workshop.
Does not cover a line running outdoors in winter: at +3 °C dew point, water forms again as soon as the pipe gets colder, and it freezes. Nor does it cover a specification that writes an oil class.
A process to protect
Fine automation, painting, bonding, packaging, cutting, machine tools. The air drives or blows, with no food contact.
The same dew point as workshop air, +2 to +10 °C, but finer filtration upstream: oil aerosols are what ruins a valve block or a paint finish.
Covers neither frost, nor food contact, nor air used to dry a product. Above 16 bar the housings change: high-pressure filtration takes over.
Dry, oil-free air at the point of use
Food industry outside direct contact, instrumentation, laboratory, laser cutting, lines running outdoors, storage of hygroscopic products.
Dew point -40 °C with a heatless adsorption dryer, which is water class 2; down to -70 °C with the heated version, which is class 1. Water no longer forms, even outdoors in winter.
Activated carbon never comes first in the chain: a coalescing filter always precedes it, or liquid oil floods the bed within days. And oil-free air obtained by treatment is not a Class 0 machine: if your documents write Class 0, move to the next level.
Class 0 is written in the specification
Pharmaceuticals, cosmetics, electronics, semiconductors, direct food contact, bottling.
The dew point is handled as in the previous level, by adsorption. What changes is where the air comes from: Class 0 is no longer obtained by the chain, it is carried by the machine and verified by a TÜV test.
A lubricated compressor followed by a treatment chain can deliver compliant air at the point of use, and it is often the most economical choice. But it does not make a Class 0 machine: if the audit asks for the machine's certificate, the chain will not replace it.
Then the chain no longer decides, the machine does. Here is the order in which we choose them, and why.
Our order of preference for Class 0
When a specification says Class 0, CEZIUM quotes an oil-free machine, as the trade understands it: scroll compressor up to 5 m³/min, rotary tooth compressor from 2.3 to 8.6 m³/min, dry screw or centrifugal beyond that. We also point out the alternative few suppliers mention: a lubricated screw followed by a treatment chain delivers oil-free air for a markedly lower purchase price, without carrying the Class 0 label.
In this trade, Class 0 means an oil-free machine. That is the convention, and it is what a specification expects when it writes Class 0, so that is what we quote. Technically, ISO 8573-1 classifies air at the point of use rather than the compressor, so a lubricated screw followed by multi-stage filtration and an adsorption dryer delivers oil-free air measured on acceptance. That is a genuine alternative, cheaper to buy and far better at heat recovery, but it does not give you a Class 0 certified machine. Both are worth knowing; your own documents decide.
| Rank | Technology | Catalogue flow | Power | Class 0 | Recoverable heat | Purchase cost |
|---|---|---|---|---|---|---|
| 01 | Scroll compressor | 0.24 to 4.96 m³/min | 2.2 to 45 kW | Oil-free machine | Low | Moderate |
| 02 | Rotary tooth compressor | 2.3 to 8.6 m³/min | 15 to 55 kW | Oil-free machine | Low | High |
| 03 | Dry screw compressor | 7.8 to 46 m³/min | 45 to 250 kW | Oil-free machine | Limited | Very high |
| 04 | Centrifugal compressor | 48 to 3,000 m³/min | 198 to 12,055 kW | Oil-free machine | High | Very high |
| 05 | Lubricated screw + treatment chain | 1.1 to 54 m³/min | 7.5 to 250 kW | Treated air, no label | High | Low |
Flow rates and power ratings taken from the CEZIUM catalogue, oil-free technologies and variable-speed lubricated screw. Purchase cost is given in relative ranks, at comparable flow.
- 01
Scroll compressor
Up to 5 m³/minThe first choice below 5 m³/min: oil-free by design, quiet, compact. The right format for a laboratory, a dental practice or a small production line.
See the 13 catalogue models - 02
Rotary tooth compressor
2.3 to 8.6 m³/minAbove the scroll range and up to 8.6 m³/min. The rotors never touch: no friction inside the chamber, minimal wear, TÜV-certified Class 0. Beyond that flow, several units run in parallel.
See the 14 catalogue models - 03
Dry screw compressor
7.8 to 46 m³/minThe answer at high flow when the specification says Class 0. We also state its downside: it costs a great deal to buy and lends itself poorly to heat recovery. If your documents ask for oil-free air rather than a certified machine, the previous step is worth quoting alongside.
See the 20 catalogue models - 04
Centrifugal compressor
From 48 m³/minReserved for the continuous base load of very large sites, where no screw compressor can carry the flow in a single machine.
See the 11 catalogue models - 05
Lubricated screw + treatment chain
Alternative, above 8.6 m³/minThe alternative, when your specification asks for oil-free air rather than a certified machine: multi-stage filtration and an adsorption dryer behind a lubricated screw, with acceptance measurement at the point of use. Markedly lower purchase price, and compression heat is recovered from the oil circuit, which a dry machine does poorly. Rule it out if your documents say Class 0.
See the 17 catalogue models