Oil-free compressor

Oil-free compressors deliver air with zero oil carry-over from the compression process itself. They achieve this through dry-running screws coated with PTFE or similar, scroll compressors with sealed crankcases, water-injected screws, or specialty pistons. ISO 8573 Class 0 is the rigorous certification for “oil-free” in the regulatory sense.

What it is

Where oil-flooded machines inject oil for sealing and cooling, oil-free machines either accept the efficiency penalty of running dry or substitute another sealing fluid (water, in water-injected screws). Two-stage oil-free rotary screws are the standard for medium and large oil-free duty; scrolls dominate the smaller end of the range. Oil-free pistons exist but are limited in capacity.

Why it matters

Oil-free is mandatory for applications where any trace of hydrocarbon contamination causes regulatory failure or product damage: medical breathing air, dairy and beverage filling, semiconductor fabrication, pharmaceutical filling, paint spraying for automotive OEM. The penalty is cost and complexity. Oil-free machines cost 30-50 percent more than equivalent oil-flooded, and their efficiency is typically 5-10 percent lower.

How it is used in our catalog

Browse oil-free options across scroll compressors and oil-free rotary screws. The breathing-air archive isolates units rated for SCBA and grade-D applications.

Common questions

Is “oil-less” the same as “oil-free”?

Marketing terms. Strictly, “oil-less” usually means no oil in the compression chamber but oil in the crankcase (e.g., some piston designs). “Oil-free” implies no oil anywhere in contact with the air. ISO 8573 Class 0 is the certifiable standard.

Can I just filter an oil-flooded compressor to oil-free quality?

Filtration can reduce carry-over to undetectable levels in normal operation, but it cannot match the regulatory and audit posture of a true oil-free machine. Critical applications require Class 0 certification at the machine.