Oil Free Screw: What the Term Really Means

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The shorthand "oil free screw" is everywhere in compressor marketing, yet it hides meaningful differences. For a buyer, the critical question is not whether a machine is called oil-free, but how it achieves — and proves — that status. CMN's answer is a water-lubricated single-screw design certified to Class 0.

What "Oil Free Screw" Usually Refers To

The term generally describes screw-type compressors that deliver oil-free discharge air. Variations include:

Dry screw oil-free (no liquid in chamber, coated rotors).
Water-injected / water-lubricated screw (water as medium).
Oil-injected screw with downstream oil removal (not truly oil-free at source).

The Proof Is in the Standard

Calling a unit "oil free screw" is not enough. Buyers should ask:

Which ISO 8573-1 class is claimed?
Is it third-party verified (e.g., TÜV)?
Does the certificate cite ISO 8573-1:2010 Class 0?

CMN's certification is TÜV-verified to ISO 8573-1:2010 Class 0 — the strictest purity class.

How CMN Delivers True Oil-Free Screw Air

Single screw + two star-wheels, water-lubricated.
Water seals and cools; no oil enters the chamber.
Near-isothermal compression (~40–50°C).
PMVSD models for variable-demand savings.

What to Check Before You Buy

Question	Why
Class and cert body	Confirms real purity
Lubrication method	Shows if oil is removed or absent
Pressure range	Must match application
Service model	Affects lifetime cost

CMN covers 2–40 bar with models from CM75G to CM320GPV, including medium-pressure PET variants.

Conclusion

"Oil free screw" should mean oil-free at the source, verified by standard. CMN's water-lubricated single-screw compressors meet that bar with TÜV ISO 8573-1:2010 Class 0 certification and a full 2–40 bar range.

CTA: Contact CMN to clarify oil free screw options for your plant, or send your requirements for a quote.

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