The difference between oil-free screw compressor and oil injector

Oil-free screw compressor and oil-injected screw compressor are two common types of air compressors, which are significantly different in terms of working principle, performance characteristics, application scenarios, advantages and disadvantages. Here are the differences between them:

1. working principle

1. oil-free screw compressor:
   • compression process: Two precision-machined spiral rotors (a male rotor and a female rotor) rotate in opposite directions in the compression chamber, gradually compressing the air sandwiched between the screw and the housing.
   • Lubrication method: oil-free lubrication, Relying on the strict tolerance of the rotor and advanced sealing technology to prevent air leakage.
2. oil-injected screw compressor:
   • compression process: The screw is used to compress the air, and lubricating oil is injected during the compression process to cool and lubricate the compression cavity.
   • Lubrication method: oil injection lubrication lubricating oil plays multiple roles in the compression process, such as cooling, lubrication and sealing.

2. performance characteristics

3. Application Scenarios

1. oil-free screw compressor:
   • high cleanliness demand industry: Such as food, beverage, medical, electronic, pharmaceutical, etc., to avoid oil pollution affecting product quality.
   • Special process such as laboratory gas supply, precision instrument manufacturing, etc.
2. oil-injected screw compressor:
   • general Industrial Field: Such as factories, mines, construction, petrochemicals, tire manufacturing, electricity, etc., to provide compressed air for pneumatic equipment.
   • Refrigeration industry: Provide compressed refrigerant for cold storage, refrigerated trucks, etc.

4. advantages and disadvantages

5. Summary

• selection basis:
  • if required high cleanliness compressed air(e. g. food, medical, electronic industries), choosing oil-free screw compressor.
  • If required high-efficiency, low-cost compressed air(e. g. general industrial scenario), select oil-injected screw compressor.

The two compressors have their own advantages and disadvantages. Users should choose the most suitable type according to actual needs (such as air quality requirements, budget, and maintenance capabilities).