Oilfree air compressors are being used more and more. What is an oilfree compressor? Oilfree air compressors refer to compressors that do not use lubricating oil in the compressor cylinder.
The Distinction Between Oil and Oilfree Air Compressors
The difference between oilfree air compressors and oil-lubricated air compressors: The term “oil-containing” and “oilfree” in air compressors generally refers to the amount of oil in the gas discharged from the air compressor’s exhaust port. Generally, oil-containing compressors have a higher oil content, while oilfree compressors have an oil content of 0.01ppm. Therefore, this oil content is used to distinguish oil-containing and oilfree air compressors.
Overview of the Advantages and Disadvantages of Oilfree Air Compressors
Now, we mainly look at the advantages and disadvantages of oilfree air compressors.
Advantages of Oilfree Screw Air Compressors
Oil-saving: The use of oil-lubricated air compressors significantly wastes lubricating oil. Taking a high-quality 7.5KW oil-lubricated air compressor as an example, it consumes at least 5 kilograms of lubricating oil per month. Over the course of a year, the cost of using lubricating oil will increase by 60 kilograms.
Convenience: Using oilfree air compressors enables a one-stop oilfree operation, directly reducing the oil intake to the back end from the source, which is relatively more convenient.
At present, water removal equipment such as refrigerated dryers, non-thermal renewal dryers, and micro-thermal renewal dryers lose their water removal function due to oil in the compressed air. The clean and oilfree gas compressed by the fully oilfree compressor fully protects the water removal equipment and reduces the additional capital occupation caused by the maintenance of the water removal equipment.
The Disadvantages of Oilfree Screw Air Compressors
In addition to the common features presented in the above table, oilfree screw air compressors also have some specific situations as follows:
The exhaust temperature of the main unit is extremely high
The exhaust temperature of the main unit of a general oilfree screw compressor can reach 180℃. Usually, factories will take some protective measures before leaving the factory. However, special attention should still be paid to high-temperature components during operation to avoid scalding or even fire hazards.
Maintenance issues after the main unit is damaged
At present, except for a few manufacturers that offer oilfree mainframe repair services, all other manufacturers require direct replacement of the mainframe, and the cost of replacing the mainframe is extremely high.
The problem of coating peeling off on the oilfree screw
There are currently two types of coatings for oilfree screw compressors. One is Teflon with average performance, and the other is molybdenum disulfide, which is much better. No matter which of the above, they all have a service life and at the same time have relatively high requirements for moisture. Therefore, when the oilfree screw compressor is not in use, it is necessary to frequently rotate the machine to prevent the main unit from getting stuck due to long-term inactivity. The frequent occurrence of host freezing faults is all caused by such reasons.
The following is a summary table of the advantages and disadvantages of oil-free screw air compressors, which can present their features more intuitively.
| Category | Feature | Specific Description | Example/Explanation | Impact |
| Advantages of Oil – Free Screw Air Compressors | Oil – saving | It reduces the consumption of lubricating oil. | Taking a high – quality 7.5KW oil – lubricated air compressor as an example, it will incur an additional cost of 60 kilograms of lubricating oil per year. In contrast, the oil – free type avoids this cost. | Lowers long – term operating costs related to lubricating oil purchase. |
| Advantages of Oil – Free Screw Air Compressors | Convenience | Provides one – stop oil – free operation, preventing oil from entering the backend systems. | During the compression process, since no lubricating oil is used in the cylinder, there is no oil that can flow into the subsequent pipelines and equipment. | Reduces the complexity of system maintenance and the need for additional oil – separation devices. |
| Advantages of Oil – Free Screw Air Compressors | Protection of water removal equipment | The clean oil – free compressed gas is beneficial for water removal equipment. | Compressed air often contains moisture, and the presence of oil in the air can affect the performance of water removal devices such as refrigerated dryers, heatless regeneration dryers, and micro – heat regeneration dryers. The oil – free compressed gas ensures these devices work effectively. | Reduces additional capital expenditures for the maintenance and repair of water removal equipment, and extends their service life. |
| Disadvantages of Oil – Free Screw Air Compressors | High exhaust temperature of the main unit | The exhaust temperature of the main unit is generally high. | It can reach 180℃ during normal operation. | During operation, special attention should be paid to high – temperature components to prevent scalding of operators and potential fire hazards in the working environment. |
| Disadvantages of Oil – Free Screw Air Compressors | Difficulty in main unit repair | Most manufacturers have strict requirements for main unit repair. | Instead of repairing the damaged main unit, most manufacturers require direct replacement. | The replacement cost of the main unit is very high, which significantly increases the long – term operating costs of the air compressor. |
| Disadvantages of Oil – Free Screw Air Compressors | Requirements for the coating | There are specific requirements for the coating of the screw in the air compressor. | There are two types of coatings: Teflon with average performance and molybdenum disulfide with better performance. Both have a limited service life and high requirements for moisture. When the compressor is not in use, it needs to be rotated frequently. | If not properly maintained, the coating may wear out or detach, leading to machine jamming failures and affecting the normal operation of the air compressor. |
Comparison between oilfree air compressors and oil-lubricated air compressors matched with oil removal equipment
In fact, the use of oilfree compressed air is increasingly becoming a trend in the pharmaceutical industry. However, it is not the case that only by choosing oilfree air compressors can the oil content be reduced to below 0.01ppm. Currently, relatively mature and stable oil removal equipment equipped with oil-lubricated air compressors can also achieve oil removal below grade 0. Such mature oil removal equipment does not require frequent replacement of filter elements and other consumables. It is also relatively convenient and the overall cost is much lower.
Conclusion
Each type of air compressor has its own advantages and disadvantages. When choosing, one should make a suitable selection based on their own needs. There are no strict regulations. Only by recognizing the pros and cons of each type of air compressor and making a full understanding can it be conducive to the selection.