Does the air compressor need refueling?

Whether the air compressor needs refueling depends on its type and design. The following are the lubrication requirements and instructions for different types of air compressors:

1. Air compressor that needs refueling (oil-lubricated type)

1. Oil injection air compressor (most common)

• Working principle: Lubricating, cooling, sealing and noise reduction are used to lubricate, cool, and the lubricating oil participates in the compression process to form an oil-gas mixture.
• Necessity of refueling: Special compressor oil must be added/replaced regularly (ordinary oil cannot be replaced), otherwise it will cause:
  • Wear of parts (bearings, rotors, pistons, etc.);
  • Poor heat dissipation, high exhaust temperature, and even causing shutdown;
  • Seal failure and compression efficiency decreases.
• Maintenance points:
  • Oil level inspection: Observe the oil level through an oil mirror before starting up, and it must be between the upper and lower limits;
  • Oil change cycle: According to the manufacturer’s recommendations (usually 500 – 1,000 hours for mineral oil and 2,000 – 4,000 hours for synthetic oil), or judged according to the color/viscosity change of the oil;
  • Oil filter replacement: Replace the oil filter simultaneously to avoid impurities contaminating the lubricating oil.

2. Low-oil lubricated air compressor (such as small piston type)

• Features: The compression chamber is lubricated with a small amount of oil (such as piston rings, cylinders), but no oil circulation system is formed.
• Refueling requirements: The specified type of lubricating oil needs to be replenished regularly to the crankcase or lubrication point, with a small amount and a lower maintenance frequency than that of oil injection.

2. Air compressor without refueling (oil-free lubrication type)

1. Oil-free air compressor (completely oil-free design)

• Working principle: The compression chamber is made of non-metallic materials (such as PTFE piston rings, ceramic bearings) or dry sealing. No lubricating oil is used to participate in the compression process, and the output air is free of oil.
• Advantages: Suitable for medical, food, electronics and other scenarios with high air quality requirements.
• Note: Although there is no oil in the compression chamber, mechanical parts such as bearings and gearboxes may require a small amount of lubricating grease (non-circulating oil), which needs to be replenished regularly according to the instructions (usually long-term lubrication with low maintenance frequency).

2. water-lubricated air compressor

• Special type: Pure water is used instead of lubricating oil for cooling and sealing. The compression chamber is oil-free, but regular replenishment and filter element replacement are required to avoid scale affecting performance.

3. How to judge whether your air compressor needs refueling?

1. Check the instructions: All air compressors will clearly mark the lubrication type (“oil lubrication”,”no oil” or “little oil”) and maintenance requirements, which is the most direct basis.
2. Observe the structure:
   • Oil injection air compressors usually have separate oil tanks, oil filters, oil coolers and other components, and the exhaust pipe may have slight oil mist (normal phenomenon);
   • The oil-free air compressor has a simpler structure, no fuel tank, and no oil mist in the exhaust pipe.
3. Application scenarios:
   • Industrial-grade large and medium-sized air compressors (especially screw types) are mostly oil-lubricated;
   • Small silent air compressors and medical/laboratory air compressors are mostly oil-free.

4. Precautions for refueling (for oil-lubricated types)

1. Use special oils: Compressor oil must withstand high temperatures, high pressures and oxidation. Ordinary oil will deteriorate rapidly, causing carbon deposits and failures.
2. Avoid mixing: Different brands/models of lubricants may have different formulas, and mixing may cause precipitation or failure.
3. Stop and refuel: Be sure to operate after the air compressor is completely stopped and the pressure is released to avoid burns or oil spraying.
4. Regular maintenance: Neglecting oil change is one of the main causes of air compressor failure. It is recommended to formulate a maintenance plan (such as checking the oil level quarterly and replacing lubricating oil and filter elements every year).

summary

• Oil-lubricated air compressors (most industrial use) must be refilled and special compressor oil needs to be replaced regularly;
• Oil-lubricated air compressors (such as medical and food grade) do not require the addition of compressor oil, but may require grease lubrication of bearings and other components (simple maintenance).

Final recommendation: The equipment manual shall prevail. If it is unclear, you can check the official information through the brand model number, or contact after-sales confirmation to avoid equipment damage caused by improper lubrication.