Are air compressors oil free or oilless?

When you’re in the market for an air compressor, you might encounter the terms “oil-free” and “oilless.” At first glance, you might think they’re the same, and they’re often used interchangeably. However, there’s a subtle difference worth noting.

When we talk about oil-free air compressors, there’s no oil in the compression area, but there might be oil in parts like the crankcase or transfer case. Examples of these air compressors are oil-free rotary screws with lubricated driving gears, oil-free reciprocating compressors with a lubricated crankcase, or liquid ring compressors.

Standards say oil-free compressors need a vent to spot malfunctions. If something goes wrong, oil might get into the compression chamber, leading to oil-contaminated air reaching places it shouldn’t. That’s why specific filters, alarms, and other safety features are crucial.

Oil-free compressors also need to monitor hydrocarbons in medical air applications, which can be expensive. Because of this, they’re not often used in medical settings.

On the other hand, oilless compressors are more common in medical air setups. They don’t use oil at all, and with extensive drying and filtering processes, they pretty much eliminate the risk of air contamination.

Let’s talk about oilless compressors.

Oilless compressors have no oil in them—not in the compression area or the drive area. Some use sealed bearings that are lubricated differently.

In recent years, oil-less scroll compressors have become the go-to in the medical industry. They’re powerful, take up less space, are quieter than many other compressors, and don’t waste water since they’re air-cooled. Plus, they’re known for being reliable even when working around the clock.

Medical air compressor designs are evolving. Thanks to scroll technology, we’re seeing more “banked” systems. Instead of one big, costly compressor, healthcare facilities now use multiple smaller scroll compressors. Together, these units meet the necessary capacity and provide the needed redundancy.

The compressors alternate based on demand, running only as much as needed. This system not only saves energy but also extends the life of each compressor.

The benefits of oil-free and oilless air compressors

Glass bottles in production in the tray of an automatic liquid dispenser

Oil-free or oilless compressors are a better fit for industries requiring ultra-clean air and lower maintenance and offer convenience for lighter, more portable tasks.

These compressors produce air that is free from contaminants, making them ideal for applications such as food and beverage processing, pharmaceuticals, medical and electronics manufacturing. Without oil changes, they require less routine maintenance, which can reduce downtime and operational costs. Eliminating oil reduces the risk of oil spills and contamination, making them more environmentally friendly.

The term “Oil-Free” is the most common and seems to be the standard language when referring to these types of air compressor units. Pilot Airs’ range is technically “oil-less” as no oil exists in the model, making it impossible for oil to enter the compressed air system. As we mentioned at the top, you may encounter an “oil free” model that may use oil in the crankshaft or transfer case and you should check this out with the manufacturer beforehand.

Aside from this very subtle difference, some confusion may result from the use of the hyphen. Oil-Free assumes the machine is free of oil, whereas Oil-Less assumes less oil is required when it is actually oilless, meaning no oil at all.

It is as clear as mud, and it can be put down to a marketing strategy many moons ago, where the term “Oil Free” proved sticker than the more accurate term “Oilless”.

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