What does the user expect from a quality compressor? Clean forced air, the right pressure, long-term operation and increased resource. And this is just a part of the requirements.
With a focus on the buyer, manufacturers offer more and more advanced compressors every year. After all, pneumatics always remains relevant in the technology market. And without air supply, it will not be able to work. The modern compressor is applicable to a wide variety of types of pneumatic tools: from a screwdriver and a spray gun to a jackhammer.
But, unfortunately, the realities are such that it is almost impossible to buy a compressor that ideally meets all the desired characteristics. Of course, a lot depends on the manufacturer and the price of the compressor. But the basic problem of choice is the very structure of the compressors. They are of two types: oil and oil-free.
Design Features: What’s the Difference?
oil compressor oil free compressor
Oil-lubricated and oil-free compressors are distinguished by the main point – the availability of lubrication.
When a piston compressor is operating, friction inevitably occurs between the metal elements. Moving parts are packed tightly, they interact with each other and will inevitably be erased. A side effect of this friction is a strong heating of the piston, crankshaft and other elements.
An elementary way out of this situation is lubrication. That is, adding oil. The oil creates a thin film between the cylinder and piston walls. It reduces friction and protects parts from wear. Prevents corrosion. Also, oil enhances heat dissipation. Therefore, the possibility of overheating is greatly reduced. And design details last longer. This is how oil compressors work.
(oil piston compressor design ) ( oil free piston compressor design)
Thanks to their lubrication, oil-filled compressors are durable. They can withstand long-term continuous operation. More durable materials are often used in oil compressors. For example, the rings in the pistons are steel, the pistons themselves are cast iron. When operating an oil compressor, it is very important to fill in exactly the oil that is indicated in the technical data sheet of the model. Do not add any engine and transmission oils. Most often, the manufacturer indicates the type of synthetic oil that is available for a given compressor.
Oil-free compressors are completely devoid of lubrication. Friction and movement of parts is carried out in a “dry” chamber. This increases the operating temperature. Many manufacturers try to reduce overheating in an oil-free compressor in any way possible. For example, screw models often use water injection into the compression chamber. The piston models use materials with a low coefficient of friction. But all the same, frictional forces cannot be avoided. Hence the short service life of oil-free compressors.
Advantages and disadvantages
It would seem, what is easier? Fill each compressor with oil and do not worry about friction. Why design an oil-free compressor when it is known to have a small resource? Everything seems to be correct. Yes, only there is a “little fly in the ointment” in the oil compressor. And she is able to spoil the “big barrel of honey”, which is the lubrication of rubbing parts with oil.
The fact is that the oil manages to get into the compressed air supplied by the compressor. It is good when this happens, for example, in a pneumatic wrench. Oil droplets will lubricate the joints. They will be easy to spin and twist. But imagine a drop of oil in a spray gun. The result is disastrous – a car painted with paint along with oil. Catastrophe. Or know-how. But not high quality work.
So, the main disadvantage of an oil compressor is the admixture of oil in the forced air. In addition, the minuses of oil compressors include:
- The need for expensive compressor oil
- The need for periodic filling
- Need constant monitoring and oil change
- Higher price of the compressor itself due to the complex design
- Some weight gain
In fact, such disadvantages are small things, and not so important. But we get really important benefits :
- Reliability. Several times longer service life. The service life is increased, since the parts do not wear out
- No overheating. No friction – no overheating
- The possibility of a long cycle of work. Important for many pneumatic tools
- High performance
- Economy of power consumption. The tool consumes less engine power
Oil-free compressors deliver perfectly clean air. Undoubtedly, this is their significant advantage. But it is also almost the only one. There are, however, some more advantages of oil-free compressors . They:
- Are cheaper
- Weigh less
- No oil filling or oil change required
That is, oil-free compressors save you time and money when buying. Part of the savings occurs during operation (no need to buy oil). But they are not a reliable investment. Oil-free have many significant disadvantages :
- Very small resource
- Less productivity
- No high pressure
- Low power
Therefore, buying an oil-free compressor is relevant only for certain areas of work. Where the oil type is prohibited. Or for small household jobs.
Scope of application
The pros and cons that we have indicated do not give an unambiguous answer to the question of which compressor is better, oil or oil-free. To choose the right compressor (with or without oil), two main things need to be determined:
- In what area it will be applied.
- At what working pace it will be used.
There are areas of pneumatics application where strict requirements are set. Regulations prohibit the appearance of oil particles in the blown air. Therefore, oil-free compressors are the only option. These areas include:
- Medicine. A supply of clean air is needed, for example, in a dental unit.
- Food industry. Compressed air is used for the manufacture of food products, packaging. Pharmaceuticals. Only clean air is needed to make medicines. It shouldn’t even contain any amount of impurities.
- Production of upholstered furniture.
- Painting of various elements, including cars. With pneumatic spray guns, oil must in no way get into the paint.
Apart from such important industries, oil-free compressors are often purchased for small jobs. It is cheaper and is quite suitable for simple pneumatic tools. For inflating tires, blowing air. Oil-free compressors cannot withstand long cycle times. But, for example, a screwdriver does not work for a very long time. Few seconds. During this time, there will be no overheating.
If there are no specific tasks for air purity, then the choice is always in favor of an oil compressor. Its high performance and the ability to provide the required pressure is used in many industries. Oil units are suitable for daily work for several hours. They can work for a long time. Oil models are also purchased for homework. In the country, in the house, in the garage.
Installation of oil and air filters
It is possible to make the compressor with oil produce compressed air without oil! You just need to install a filter to clean the oil.
Helpful hints:
The oil filter is a housing with a filter element inside. It is often also called a separator. There are simple single layer filters. They need to be changed more often. There are more complex oil filters. They have a built-in valve system. These filters are more expensive. But in the end you will get a compressor that will take all the strengths of the oil. At the same time, it will supply air without oil. This is often done for production purposes. When replacing the oil separator, it must be checked that it is not contaminated. A clean multi-layer filter can effectively stop oil droplets.
However, experts say that using filters is a risky step. Since it is impossible to completely exclude oil from the air. But if we are not talking about a drill, food and medicine, then the minimum amount of oil in the air is permissible. It is worth buying a reliable Pet Blowing Compressor with oil and installing a filter. Even spray guns allow oil in the air. But it should be absolutely negligible – less than 0.01 mg / m 3.
