How should I choose between oil-free and oil lubricated rotary compressors?

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 October 5, 2022

A lubricated air compressor or an oil-free air compressor is one of the choices that are made when choosing an air compressor. What are the differences between them? Which is best for you and your business ?

In general, air compressors draw in air from the atmosphere and compresses air into a storage tank from where compressed air is distributed to the point of use.

What is a Lubricated Air Compressor ?

In a lubricated air compressor, the lubrication oil keeps the rotary elements running smoothly without damaging the mechanism and helps to maintain air compression efficiency. In a lubricated compressor, oil is used for three main reasons :

  • To dissipate the heat generated.
  • To provide adequate lubrication of the moving parts (bearings and gears).
  • The oil acts as a sealant .
Lubricated Air Compressor

What are Oil-Free Compressors ?

On the other hand, an oil-free air compressor does not use any oil in the compression chambers. The screw or the rotary element is distantly positioned and maintained through lubricated timing gears outside the compression chamber. The output of compressed air is entirely oil free.

Oil-Free Compressors

What are the differences between Oil Lubricated Compressor and an Oil Free compressor?

While there are differences in the construction and working principle of both these machines, the key differences between them impacting users are as follows...

The initial cost of ownership for oil lubricated compressors is lesser than oil free compressors. However, the oil traces found in the output of the oil lubricated compressors need additional air treatment through coalescing filters and condensate treatment through oil water separators which adds to installation/maintenance cost and other energy consumption on account of a drop in pressure.

The maintenance cost of oil lubricated compressors is higher than an oil free compressor due to the cost of topping up and changing lubrication oil and the additional filtration involved in the compressor and downstream. In spite of the additional filtration, oil traces usually deposit on the air piping and other downstream handling and processing equipment that also need maintenance or replacement, which adds to the maintenance cost. This also makes the oil-lubricated compressors less environmentally friendly. Due to the lack of oil to dissipate heat, conventional oil free compressors at times have 2 stages of air compression with inter cooling to reach the desired outlet pressure, which makes the system complex and expensive when compared to an oil-lubricated compressor. However, recent innovations use water in the compression chamber to keep temperatures down, which results in a simple construction and a clean machine that is green and environment friendly.

Contact Pattons to know more about this innovative oil free product.

What is best for you ?

An oil free compressor is best suited if any of the following applies to your application or business :

  • Applications where compressed air will be allowed to interact with the end product, which is extremely sensitive to oil contaminants.
  • Applications where the equipment using compressed air is extremely sensitive to oil impurities in the air.
  • Businesses that are committed to conserving the environment and aspire for reduction of their carbon foot print.
  • Businesses whose products and operations are governed by stringent statutory and compliance regulations.
  • Businesses that aspire to keep the maintenance cost of their compressed air system down.

Some of the sensitive applications wherein oil free compressors are recommended are :

For applications / processes with air purity values specified in accordance with the international standard, ISO8573-1 is a good way to identify the application’s sensitivity to contaminants.ISO8573-1 Class ‘zero’ applications are extremely sensitive to oil, where an oil free compressor is the only logical choice.

Any other applications that are more forgiving to oil impurities in compressed air, less regulated, and light duty use will be an ideal choice for an oil lubricated compressor.

In Conclusion

Your choice of air compressor technology will be influenced by the intended use and the industry in which it will be deployed. Pattons offers ELGi’s innovative oil free compressors that are guaranteed to meet ISO 8573-1 Class Zero and a wide range of oil lubricated compressors with a best-in-class warranty.

Pattons can help you determine which air compressor is suitable for your business. Contact us today and speak with one of our air compressor experts!

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