Oil-free dry screw
Dry screw compressor, oil-free: non-contacting rotors synchronised by gears, from 45 to 250 kW. Class 0 air for large flows.
20 models in the catalogue, flow 6.8 - 43 m³/min, pressure 7 - 10 bar, noise level 69 - 74 dB(A).
How it works ↓
What is a dry screw compressor?
An oil-free screw: two rotors that never touch, held by timing gears, compress the air with no fluid at all in the chamber, often in two stages. The air leaves oil-free, class 0 as the trade understands it. It is the machine for large oil-free flows, from 45 kW.
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Made for
- Food, pharmaceuticals, electronics, semiconductors
- Air in contact with the product, at a large flow
- Specifications that call for class 0
Not made for
- A body shop or an engineering workshop: a lubricated screw is enoughFixed-speed screw
- Below 45 kW: water injection or scroll, simplerOil-free water-injected screw
| Reference | kW | HP | m³/min at 8 bar | Pressures | dB(A) | Outlet | L × W × H (mm) | Weight |
|---|---|---|---|---|---|---|---|---|
| CZ-SLTOF-45FD | 45 | 60 | 6.8 | 7/8/10 | 69 | DN50 | 2200 × 1400 × 2000 | 1,900 kg |
| CZ-SLTOF-45VD | 45 | 60 | 6.8 | 7/8/10 | 69 | DN50 | 2200 × 1400 × 2000 | 1,800 kg |
| CZ-SLTOF-55FD | 55 | 75 | 9 | 7/8/10 | 69 | DN50 | 2200 × 1400 × 2000 | 2,000 kg |
| CZ-SLTOF-55VD | 55 | 75 | 9 | 7/8/10 | 69 | DN50 | 2200 × 1400 × 2000 | 1,900 kg |
| CZ-SLTOF-75FD | 75 | 100 | 12.2 | 7/8/10 | 70 | DN50 | 2200 × 1400 × 2000 | 2,150 kg |
| CZ-SLTOF-75VD | 75 | 100 | 12.2 | 7/8/10 | 70 | DN50 | 2200 × 1400 × 2000 | 2,000 kg |
| CZ-SLTOF-90FD | 90 | 120 | 13.8 | 7/8/10 | 71 | DN50 | 2200 × 1400 × 2000 | 2,250 kg |
| CZ-SLTOF-90VD | 90 | 120 | 13.8 | 7/8/10 | 71 | DN50 | 2200 × 1400 × 2000 | 2,100 kg |
| CZ-SLTOF-110FD | 110 | 150 | 19.5 | 7/8/10 | 71 | DN65 | 3000 × 1990 × 2180 | 3,360 kg |
| CZ-SLTOF-110VD | 110 | 150 | 19.5 | 7/8/10 | 71 | DN65 | 3000 × 1990 × 2180 | 3,100 kg |
| CZ-SLTOF-132FD | 132 | 175 | 23 | 7/8/10 | 73 | DN65 | 3000 × 1990 × 2180 | 3,500 kg |
| CZ-SLTOF-132VD | 132 | 175 | 23 | 7/8/10 | 73 | DN65 | 3000 × 1990 × 2180 | 3,200 kg |
| CZ-SLTOF-160FD | 160 | 215 | 26.3 | 7/8/10 | 73 | DN65 | 3000 × 1990 × 2180 | 3,750 kg |
| CZ-SLTOF-160VD | 160 | 215 | 26.3 | 7/8/10 | 73 | DN65 | 3000 × 1990 × 2180 | 3,300 kg |
| CZ-SLTOF-185FD | 185 | 250 | 28.9 | 7/8/10 | 74 | DN65 | 3000 × 1990 × 2180 | 3,860 kg |
| CZ-SLTOF-185VD | 185 | 250 | 28.9 | 7/8/10 | 74 | DN65 | 3000 × 1990 × 2180 | 3,400 kg |
| CZ-SLTOF-200FD | 200 | 270 | 34.6 | 7/8/10 | 74 | DN100 | 4500 × 2000 × 2150 | 5,730 kg |
| CZ-SLTOF-200VD | 200 | 270 | 36.8 | 7/8/10 | 74 | DN100 | 4500 × 2000 × 2150 | 5,570 kg |
| CZ-SLTOF-250FD | 250 | 335 | 42.8 | 7/8/10 | 74 | DN100 | 5070 × 2200 × 2300 | 7,000 kg |
| CZ-SLTOF-250VD | 250 | 335 | 42 | 7/8/10 | 74 | DN100 | 4500 × 2000 × 2150 | 5,800 kg |
Flows, pressures, noise levels and dimensions recorded model by model on the catalogue sheets. Flows given at 8 bar.
The dry screw compresses with no fluid at all in the chamber: two rotors synchronised by gears, often in two stages. From 45 to 250 kW for 6.8 to 42.8 m³/min at 8 bar, it is the reference for large oil-free flows, last in the house order of preference because it is the most complex.
Below 45 kW or for a modest flow, the water-injected screw and the scroll make the same oil-free air more simply.
In a “dry” oil-free compressor, no oil enters the compression chamber. The two rotors turn without touching, synchronised by a set of high-precision timing gears; a special coating provides the seal without contact or lubricant.
Compression generally takes place in two stages with intercooling, because the absence of oil deprives the process of its internal cooling. The oil stays confined to the gear casing and the bearings, completely separated from the air flow.
The result: 100% oil-free air, certified ISO 8573-1 Class 0, the strictest quality in the standard, required wherever the slightest trace of oil is prohibited.
Processes where the air is in direct contact with the product or the patient and where oil is prohibited: food processing, pharmaceuticals, electronics, semiconductors, hospitals, laboratories, textiles, instrumentation. Class 0 certification is often a contractual requirement in these sectors.
Class 0, no oil in the chamber
No oil in the compression chamber: Class 0 under ISO 8573-1, the strictest in the standard.
Nothing rubs in the chamber
Coated stainless steel rotors, synchronised by timing gears, non-contact labyrinth seals.
Cooled two-stage design
Two-stage compression with an intercooler, to make up for the absence of oil cooling and maintain efficiency.
No oil to treat
No oily condensate to treat, no oil filter downstream, no discharge to manage.
From 6.8 to 42.8 m³/min at 8 bar
Twenty sizes from 45 to 250 kW, from 69 to 74 dB(A) depending on the model.
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 | 0.3 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 compressorthis page | 6.8 to 43 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 | 0.95 to 44 m³/min | 5.5 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 33 catalogue models
Worth reading on this technology
Lubricated screw or oil-free compressor: Class 0 describes the air, not the machine
Most comparisons set two machines against each other. The standard, however, judges the air at the point of use. A lubricated screw followed by a treatment chain can deliver oil-free air at the point of use, at a significantly lower purchase cost; class 0 itself remains that of an oil-free machine. Here is the order in which CEZIUM selects each technology.
ISO 8573-1: the complete guide to compressed air quality classes
ISO 8573-1 grades compressed air quality against three criteria, particles, water and oil, each on its own scale starting at Class 0. Which class suits which application? Full table and examples.