Oil-Injected Vs Oil-Free Air Compressor Hire

Oil-injected air compressors utilise oil to cool, seal and lubricate their compression chamber and bearings. These air compressor hire units are an ideal choice for industrial and heavy-duty applications.

Oilinjected and Oilfree Compressors on a white background

Oil-injected units can deliver compressed air efficiently, but oil contamination could negatively impact end products and processes. To minimise this risk, opt for an oil-free model.


Oil-injected and oil-free compressors differ in how they compress air. In the former, oil is injected into compression chambers to seal rotors and provide cooling.

Oil-injected air compressors rely on these processes for safe, dependable operation. However, the effectiveness of these features can be affected by oil injection parameters like flow rate, temperature, port configuration and location.

According to these factors, the compressor efficiency may differ between oil-injected and oil-free models. This could have a substantial effect on Specific Energy (kW/100 CFM) as well as overall compressor performance.

Oil-free compressors use water to cool the air and provide lubrication, while oil-injected models utilise oil. While oil-free options have a higher initial price point, they provide excellent safety in sensitive applications like dry cleaning or medical procedures where contamination could occur.


Oil-injected compressors use more energy than their oil-free counterparts, which could cost you money in the long run.

Lubricated compressors also need oil to function correctly, necessitating more maintenance and repair work over their lifespan. Fortunately, many models now come with regulators that enable them to use only the energy required, cutting fuel costs and encouraging your business to be more eco-friendly.

Oil-free compressors generally offer lower operating costs due to their fewer components. In addition, they need minimal upkeep, making them an attractive option for companies with tight budgets or limited space requirements.


Oil-injected air compressors are cheaper than their oil-free counterparts but may introduce contaminants into the compressed air stream. This could damage sensitive applications and products as well as have adverse effects on the environment.

Conversely, oil-free compressors deliver 100% oil-free air to your end product, eliminating the risk of contamination and lowering your total cost of ownership.

If your application necessitates ISO Class 0 or Class 1 air purity, oil-free compressors are the way to go. They’re often preferred in food and beverage processing, chemical and petrochemical processing, automotive paint spraying, medical electronics, and textile industries.

Like oil-injected compressors, oil-injected systems require coalescing and activated carbon filters to achieve air purity comparable to an oil-free system. Unfortunately, this increases power consumption since the oil-injected system must overcome pressure loss across these additional inline filters.


Oil-injected compressors tend to be more cost-effective than their oil-free counterparts; however, considerable expenses come into play throughout the life of an oil-injected compressor system.

Oil-injected compressors, for instance, are susceptible to lubricant carry-over of up to 4 parts per million (ppm). Not only does this cause environmental issues and impacts performance and power consumption due to the need to top off lubricant levels in the compressor sump and remove it through coalescing or carbon filters downstream.

Conversely, oil-free air compressors do not use oil in their compression chamber or cooling down process.

Instead, when you air compressor hire, you can rely on oil-free air compressors to employ an extensive sealing system between these areas and prevent oil contamination of compressed air during compression – making them perfect for applications where oily air could lead to product spoilage or damage to production equipment.