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

Comparison of advantages and disadvantages of oil-free compressor and oil-injected screw compressor

1, the use of the situation is not the same:

in the operation of the oil-free screw compressor, the lubricating oil is not in contact with the compressed gas, and the compressed gas is not polluted. The oil-injected screw compressor injects a large amount of lubricating oil during the compression process to achieve gas cooling, sealing and lubrication of the rotor. Therefore, the compressed gas contains a large amount of oil when discharged, and a post-treatment device is required to reduce the oil content of the gas.

2. The risks are different:

oil-free screw compressors do not affect the quality of the gas used by users because they do not contain oil in the compressed gas. Although the oil-injected screw compressor is processed by post-processing equipment, it still contains a small amount of oil. After a long period of operation, after reaching a certain level, the oil gradually accumulates in the network pipe, and is blown out by the compressed gas after a period of time, affecting the user's gas. Quality. In addition, its oil filter equipment, oil separator, pre-filter, post-filter, as the use of time increases, the efficiency will be significantly reduced, the oil content will increase, and the filter material has the risk of rupture, which there is an unpredictable risk.

High maintenance costs:

the maintenance point of the oil-filled screw compressor is larger than that of the oil-free machine. There are oil filter, oil and gas separator and three oil and gas filters. Oil and gas separator filter life of 4000 hours, oil filter life of 4000 hours, precision grade activated carbon oil and gas filter life of only 1000 hours. In addition, the lubricating oil of the oil-injected screw compressor is easy to be dirty, oxidized, and emulsified due to direct contact with the gas, and must be replaced regularly, otherwise it will affect the service life of the unit; the lubricating oil of the oil-free screw compressor is not in sufficient contact with the air, so L The service life of the lubricating oil is very long.

4. Operating expenses:

since the oil-injected screw compressor ensures the gas quality through several filters, the resistance loss is large and increases with the use time. The resistance is 1.01bar at the beginning and up to 1.5bar at the later stage. However, the oil-free machine is only 0.3bar. Therefore, the operating cost of oil-injected screw compressors is higher, and the work done is more than that of oil-free screw compressors.

5. Environmental pollution:

because the gas of the oil-injected screw compressor contains oil, and the condensed water also contains oil, direct discharge will cause environmental pollution, and the oil-free screw will not cause such a problem.