* Oil-Free Compressor: These compressors use no oil for lubrication. Instead, they rely on other methods, such as:
* Dry running: Components are designed with materials and tolerances that minimize friction and wear without any lubrication. This is typically more expensive to manufacture.
* Special coatings: Components are coated with materials that reduce friction.
* Gas lubrication: Some designs use compressed air itself as a lubricant.
Advantages: The biggest advantage is the completely oil-free compressed air output. This is crucial in applications where even trace amounts of oil contamination are unacceptable, such as:
* Food and beverage processing: Prevents contamination of products.
* Pharmaceutical manufacturing: Maintains product purity.
* Electronics manufacturing: Prevents damage to sensitive components.
* Medical applications: Ensures sterile environments.
Disadvantages: Oil-free compressors are typically:
* More expensive: Due to the more complex design and materials.
* More prone to wear: Requiring more frequent maintenance.
* Potentially less efficient: Though efficiency is improving with newer designs.
* Oil-Injected (or Oil-Lubricated) Compressor: These compressors use oil for lubrication of internal components like pistons or rotors. The oil is mixed with the compressed air. There are different types, with some offering better separation than others.
* Advantages: Generally:
* Less expensive: Simpler design and construction.
* More efficient: Oil lubrication reduces friction and wear.
* Longer lifespan: With proper maintenance.
* Disadvantages: The major disadvantage is the presence of oil in the compressed air, making it unsuitable for many applications. However, some oil-injected compressors include an aftercooler and oil separator to remove most of the oil, but some trace amounts usually remain. This "oil-lubricated" air is still not suitable for the above mentioned sensitive applications.
In short: Choose an oil-free compressor when air purity is paramount. Choose an oil-injected compressor when cost and efficiency are primary concerns and oil contamination is acceptable or can be adequately filtered out. The specific application dictates the best compressor type.
