Oil-flooded (oil-injected) compressor

Oil-flooded (also called oil-injected or oil-lubricated) compressors inject oil directly into the compression chamber. The oil does three jobs at once: it seals the running clearances between rotors or vanes, it carries away heat of compression, and it lubricates contacting parts. After compression, a series of separators and coalescing filters removes the oil from the air stream.

What it is

Most rotary screw, rotary vane, and rotary tooth compressors in industry are oil-flooded. The injected oil dramatically improves efficiency and reliability versus dry-running alternatives. A modern oil-flooded screw can typically deliver compressed air with 1-5 ppm residual oil carry-over, further reducible by aftermarket filtration to under 0.01 ppm.

Why it matters

Oil-flooded machines are simpler, cheaper, and more efficient than oil-free designs of comparable flow. For applications that tolerate residual oil (general plant air, pneumatic tools, sandblasting), they are the default. For applications where any oil is unacceptable (food contact, electronics, medical, breathing air), oil-free is required or oil-free-equivalent filtration is added.

How it is used in our catalog

The majority of rotary screw compressors in our catalog are oil-flooded; filter by lubrication type to compare against oil-free scrolls and Class 0 oil-free screws. The air dryers section pairs with oil-flooded machines for downstream water and oil removal.

Common questions

Is oil-flooded air safe for tools and machinery?

For general plant pneumatic tools and most production equipment, yes. The trace oil carryover actually helps lubricate tools. Sensitive processes (electronics, pharma, food contact) require additional filtration or oil-free machines.

What does maintenance look like?

Oil and oil filter changes every 2,000-8,000 hours depending on oil type, plus annual coalescer changes and periodic separator replacement.