Does oil-free air compressor need lubricating oil for maintenance?

Oil-free air compressors usually do not need to use lubricating oil during maintenance. However, its core components (such as bearings, gears, etc.) still need special lubrication methods (such as grease, solid lubrication or self-lubricating materials) to reduce friction and wear. The following is a detailed analysis:

the core characteristics of 1. oil-free air compressor

oil-free air compressor is designed completely eliminate oil pollution in compressed air, To meet the high air quality requirements of the scene (such as medicine, food, electronics industry). Its core features include:

1. oil-free compression technology: Through water lubrication, ceramic coating, self-lubricating materials or air bearings and other technologies, to avoid the contact between lubricating oil and compressed air in traditional air compressors.
2. Clean output: Oil content of compressed air ≤ 0.01 mg/m & sup3;, in line with ISO 8573-1 Class 0 or Class 1 standard, can be directly used in aseptic production or precision instruments.

Do you need lubricating oil for 2. maintenance?

1. Completely oil-free air compressor (such as water-lubricated oil-free screw machine)

• compression chamber: Water is used as lubricating and cooling medium without lubricating oil. Water forms a water film during compression, reducing direct metal contact while absorbing heat.
• Transmission parts:
  • bearing: Usually used high temperature grease(Such as polyurea-based grease) for regular replenishment, but the frequency of replenishment is much lower than that of oil air compressors (maybe once every 1-2 years).
  • Gearbox if it is designed for independent gearbox (such as some large oil-free screw machines), it may be necessary to use special gear oil however, it should be completely isolated from the compression chamber to prevent oil leakage.
• Maintenance focus:
  • regularly replace the water filter to prevent clogging of scale.
  • Check the waterway tightness to avoid water leakage into the compressed air.
  • Replenish bearing grease (as per instructions).

2. Dry oil-free air compressor (such as oil-free piston machine, scroll machine)

• compression chamber: Realize oil-free compression with ceramic coating, PTFE (polytetrafluoroethylene) self-lubricating material or air bearing without lubricating oil.
• Transmission parts:
  • piston ring/cylinder liner: Using self-lubricating materials (such as graphite, polyimide), no additional lubrication is required.
  • Bearing: Use long-lasting grease(Such as lithium-based grease), only need to check the lubrication status during maintenance, no need to add frequently.
• Maintenance focus:
  • clean the air filter to prevent dust from entering the compression chamber.
  • Check the wear of the transmission parts and replace the self-lubricating material if necessary.
  • Replenish bearing grease (as per instructions).

"Lubrication-related" matters to be paid attention to during 3. maintenance

1. avoid misuse of lubricating oil:
   • it is strictly forbidden to use lubricating oil in the compression chamber or parts in contact with compressed air, otherwise it will directly pollute the compressed air and cause the product to be unqualified (such as excessive oil content in drug production).
   • If you need to lubricate the transmission parts (such as bearings, gears), you must use completely isolated from compressed air the special lubricant and ensure tightness.
2. Selection of grease:
   • to be selected according to the equipment manual high temperature, long life grease(such as working temperature ≥ 120 ℃ polyurea grease).
   • Avoid the use of ordinary grease, because it may be due to high temperature decomposition or volatilization, resulting in lubrication failure or pollution of the environment.
3. Maintenance cycle:
   • oil-free air compressor maintenance cycle is usually longer than the oil air compressor (such as bearing grease replenishment cycle may be 2 years, and oil air compressor need to change the oil every 3-6 months).
   • Strictly follow the instructions to avoid excessive maintenance or neglect of key parts inspection.

4. typical maintenance process (water lubricated oil-free screw machine as an example)

1. daily inspection:
   • check whether the water pressure and temperature are normal.
   • Observe whether the drain valve automatically drains water to avoid condensate accumulation.
2. Monthly maintenance:
   • clean the air filter and replace the primary filter element.
   • Check the differential pressure of the water filter and replace the filter element if necessary.
3. Annual maintenance:
   • replenish bearing grease (if required).
   • Check drive belt tension (if any) and adjust or replace if necessary.
   • Chemical cleaning of waterways to remove scale.
4. Overhaul maintenance (every 3-5 years):
   • replace the main engine bearings, seals and other wearing parts.
   • Check the wear of the screw rotor and return it to the factory for repair if necessary.

5. Summary

• oil-free air compressor maintenance, the compression chamber itself without lubricating oil however, transmission parts (such as bearings, gears) may require the use of grease or special gear oil.
• Key Principles: The lubricant must be completely isolated from the compressed air to prevent contamination of the output gas.
• Recommendations:
  • select the type and brand of lubricant in strict accordance with the equipment instructions.
  • Entrust professionals to carry out maintenance to avoid equipment damage or air pollution caused by misoperation.
  • Establish maintenance files to record key information such as lubricant replenishment and component replacement to ensure traceability.

Through scientific maintenance, oil-free air compressor can run stably for a long time, providing continuous and clean compressed air for high demand industries such as medicine and food.