The difference between oil-injected screw and oil-free screw

The difference between oil-injected screw and oil-free screw is mainly reflected in the following aspects:

lubrication method:

oil injection screw: during the compression process, the cooling lubricating oil is directly injected into the body through the nozzle from the lower part of the oil and gas separator and mixed with air. The oil not only plays the role of lubricating the rotor, but also takes away the heat generated by compression, while forming an oil film to close the gap and reduce compression noise.

Oil-free screw: no need to use lubricating oil, but through the small air gap between the screw and the screw sleeve to achieve self-lubrication, so it is also called dry screw compressor.

Oily gas:

oil injection screw: the output of the gas is containing oil, if the gas quality requirements are higher, you need to add oil filter equipment at the back end.

Oil-free screw: the output of the gas is completely oil-free, suitable for high gas quality requirements, no additional oil filter equipment.

Maintenance costs:

oil injection screw: Due to the use of lubricating oil, it needs to be replaced regularly, and there are many accessories involved in maintenance, and the maintenance cost is relatively high.

Oil-free screw: maintenance and replacement of fewer parts, maintenance is more convenient, the cost is relatively low.

Application occasions:

oil injection screw: widely used in mining, machinery manufacturing, construction and other places where the oil content of the gas is not so strict.

Oil-free screw: especially suitable for pharmaceutical, electronics and other industries that require high gas quality, because it does not produce oil mist and pollution.

Price:

generally speaking, oil-free screw compressors are more expensive than oil-injected screw compressors due to their uniqueness and high technical requirements.

In summary, there are significant differences between oil-injected screws and oil-free screws in terms of lubrication methods, gas oil content, maintenance costs, applications and prices. Which type of compressor to choose depends on the specific use needs and environmental requirements.