Which is better, oil-injected or oil-free?

There are two basic types of screw air compressors: oil-injected and oil-free.

Oil-injected (or oil-immersed) screw air compressors use oil to lubricate the screw unit and ensure its smooth operation. The oil also helps cool the compressed air and prevents the equipment from overheating. After compressing the air, an oil separator is used to remove the oil. A small amount of oil (oil residue) may remain in the compressed air, which can be further reduced using in-line filtration. Oil-injected compressors are the most common type of screw air compressor and are suitable for most applications.

Oil-free (or oil-free) screw air compressors are water-lubricated with a single screw. Air inhalation of the atmosphere without oil can ensure the cleanliness of the gas. Oil-free screw air compressor compressed gas is very clean air, do a hundred percent oil-free.