Published: 19/10/2021
Oil Free VS Oil Compressors: Which One Should I Buy?
When buying an air compressor, knowing which type of compressor to choose for your application can be difficult. Two of the most popular types of air compressors are oil lubricated and oil free compressors.
Although both types of air compressors perform the same function (compressing air), they’re very different in the way that they work, the way they’re made, and the applications they are designed for.
In this guide, we’ll explore how both types of compressors work, how they differ, and how to choose the right one for your needs.
How do air compressors work?
Air compressors work by drawing in air and compressing it to create pressure, which then generates energy to power the appliance. Some compressors require more lubrication than others to prevent friction or seizing of the moving parts inside.
How do oil free air compressors work?
Oilless air compressors operate without oil as the compression chamber is pre-lubricated and equipped with a permanent lubricated coating (usually Teflon). This helps to create a smooth and frictionless surface and provides a shield for the piston parts when they’re working.
Different types of oil free compressors available are ;
- Oil free rotary screw compressors
- Oil free piston compressor
- Oil free scroll compressor
- Oil free rotary lobe compressor
How do oil lubricated air compressors work?
Oil lubricated air compressors use oil to protect the moving parts inside which prevents friction and damage. The compressors require re-oiling on a regular basis to ensure reliability and maintain their lifespan.
There are different types of lubrication used within oil based air compressors:
Pressure system
This lubrication system is used within industrial compressors and rotary compressors. High pressure oil is forced through the chambers of the compressor using an oil pump to ensure all parts are lubricated well.
The steam from the oil can also act as an efficient way to prevent the piston head from overheating
Splash system
This is the most common type of lubrication system. An oil dipper is used on the piston’s connecting rod. It reaches inside the oil pump and sprinkles oil across the bearings, including the piston chamber upon each revolution.
Choosing the right air compressor for your needs: Factors to consider
There are several key differences between the two types of air compressor that should be considered before making your choice.
Maintenance
Oil based air compressors need more maintenance than their oil free counterparts. They require routine maintenance.
This is because the oil needs to be changed regularly, depending on the type of compressor you have and the amount of usage it gets. Each compressor has its own requirements for how often the oil should be changed so this is something to look out for when you buy your air compressor. Old oil should be removed and replaced with new oil to ensure the compressor continues to work effectively.
On the other hand, oil free air compressors are already lubricated with permanent solutions so you will never have to change the oil or lubricate them. As a result, they require much less maintenance in comparison.
Air contamination
One of the main challenges businesses face with oil-lubricated air compressors is the risk of oil contaminating the compressed air. While this may not be an issue for all applications – for instance, in car garages where minor oil contamination doesn’t affect air tools or power tools – it can be highly problematic for others.
If your business requires uncontaminated air, an oil-free air compressor is essential. Although air filters can be added to oil-lubricated compressors to reduce oil contamination, they may not fully eliminate the risk, especially in sensitive applications. For example, in industries such as food production, medicine and electronics, they depend on oil-free compressors to ensure clean air and uncontaminated operations.
Durability
Oil based air compressors tend to be more durable and have a longer life expectancy than oil free versions. This is because less friction and wear and tear occurs due to the lubrication provided by the
To ensure effective running, oil level is maintained in oil compressors, whereas the permanent lubrication present in oil-free compressors will, over time, degrade; which may lead to unreliability and excessive machine noise.
This is why oil lubricated compressors are suitable for commercial applications where the compressor is used for long periods of time. The constant lubrication helps to reduce friction and keep the compressor cool during operation, maintaining a low noise performance.
Noise
Oil free air compressors can be loud. As a result, they are usually kept away from the place of work to help reduce noise levels in the workplace. However, modern oil free air compressors have been designed to run more quietly and will run 10-15 dBA quieter than older versions. So, don’t rule them out entirely!
However, due to the added lubrication, oiled compressors run smoothly with very little noise – this is one of the key differences between the two types of compressor.
If a noisy compressor will cause problems for your business and air contamination is not a problem, we recommend an oil based air compressor. Where noise is not an issue, either type of air compressor is recommended.
Applications
Oil-lubricated air compressors are ideal for heavy-duty industrial and construction applications where high power and extended run times are required. They can compress large volumes of air over long periods, making them well-suited for powering tools.
On the other hand, oil-free air compressors are lighter and more portable, making them perfect for applications where mobility is important or where less compressed air is needed, such as in the medical sector.
Cost
Oil free air compressors have a larger initial cost than oil lubricated air compressors, but they offer a longer lifespan and greater air capacity for powering larger tools and huge teams.
Most oil lubricated air compressors provide a working life of up to 50,000 hours when properly maintained. Oil changes are recommended every 2000 hours to keep the machine running smoothly. Oil changes are incredibly important so it’s crucial that they happen, however replacing the oil adds to maintenance costs.
Oil free air compressors, however, carry much lower costs of ownership over their lifetime although the initial purchase price is higher, they do not require oil changes. Despite this, oil free air compressors due to the direct unlubricated contact, have a shorter lifespan than oil lubricated compressors.
Technology advancements in the manufacturing of oil free air compressors have led to a much longer lifespan than older oil free air compressors. They can last up to 40,000 hours, which is four times longer than the older oil free air compressor and is even comparable to some oil lubricated versions.
Air Supply Ltd
Air Supply is an experienced and reliable company that has been selling, servicing and repairing compressed air equipment for over 20 years!
If you’d like more advice on how to choose between an oil free or oil lubricated air compressor, please contact our expert team.