Oil-free compressors
No oil in the compression chamber. That is what the trade means by Class 0, and what a specification expects when it says so. The technologies are chosen mostly by the flow required.
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
Scroll
13 modelsTwo nested spirals, no oil, continuous and quiet operation. The first choice below 5 m³/min: laboratory, dental practice, small production line.
Rotary tooth
14 modelsRotors that never touch: no friction in the chamber, minimal wear, TÜV-certified Class 0. The step above the scroll.
Dry screw
20 modelsCoated rotors turning at a calibrated clearance, often in two stages. The answer at high flow when the specification says Class 0.
Water-injected screw
36 modelsWater replaces oil for sealing and cooling. Near-isothermal compression, so high efficiency, with no oil in the air at all.
Centrifugal
11 modelsDynamic compression, oil-free by nature. Reserved for the continuous base load of very large sites, where no screw carries the flow alone.
Booster
9 modelsTakes network air and lifts it to process pressure, oil-free. The typical case is PET bottle blowing.
Not sure which one to pick?
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