Oil Free Screw Compressor vs Dry and Oil-Injected Types

Buyers often hear "oil free screw compressor" and assume one technology. In reality there are distinct routes to oil-free air, each with trade-offs. CMN's water-lubricated single-screw approach is one of them; this article compares it with dry oil-free and oil-injected screw types so specifiers can choose with eyes open.

The Three Routes to "Oil-Free"

• Oil-injected + filtration: oil is filtered out after compression.

• Dry oil-free: rotors run without liquid, relying on coatings and tight tolerances.

• Water-lubricated (CMN): water replaces oil in the chamber; no oil to remove.

Purity and Risk

For certified purity, CMN's TÜV ISO 8573-1:2010 Class 0 removes doubt.

Temperature and Efficiency

• Oil-injected runs warm but oil carries heat away.

• Dry oil-free runs hot, stressing coatings.

• Water-lubricated runs near-isothermal (~40–50°C), reducing waste heat.

Service Comparison

An oil free screw compressor from CMN avoids oil changes and separators. Dry types avoid oil too but face costly rotor refurbishment. Oil-injected units carry the heaviest routine service.

When Each Makes Sense

• Constant high purity + cool running → water-lubricated (CMN).

• Small, low-duty, dry locations → dry oil-free may fit.

• Cost-sensitive, non-contact air → oil-injected with filtration.

CMN's range (CM75G to CM320GPV) targets the purity-critical segments: beverage, food, pharma, electronics, textile.

Conclusion

An oil free screw compressor should be judged on how it achieves purity, not just the label. CMN's water-lubricated single-screw design achieves Class 0 air by removing oil entirely, with cooler running and simpler service than the alternatives.

CTA: Contact CMN to compare an oil free screw compressor against your current machine, or send specs for a quote.