Portable air compressors are wonderfully useful and versatile pieces of equipment and can be turned to a variety of tasks from powering hand tools to blowing up inflatable boats. However, not all air compressors are created equal, and if you're in the market for a new compressor you will have to make a difficult decision -- oiled, or oil-free?
Oil-free air compressors are a relatively modern addition to the field of portable air compression technology but have swiftly become extremely popular for the many advantages they offer over conventional oiled compressors. However, oil-free compressors also have a few disadvantages when compared to their conventional cousins, so you should consider your options carefully before deciding which type of compressor best suits your needs.
What are the advantages of choosing an oil-free air compressor?
All air compressors use one or more pneumatic pistons to compress and circulate air, and these pistons can create large amounts of friction and damaging heat if not suitably lubricated. In conventional oiled compressors, this is achieved with standard lubricating compounds which must be manually applied to the piston heads. Oil-free compressors differ in that their pistons come pre-coating with a tough, enduring lubricant (usually consisting mainly of Teflon) which will never require renewal.
As you can imagine, dodging the messy and time-consuming business of lubricating and re-lubricating your compressor's pistons can be an enormous time and labour saver. It also eliminates the need to keep lubricants on-hand when working on isolated job sites.
Since oil-free compressors do not need lubrication, they also do not need the injectors, lubricants tanks and other components required by oiled compressors to function. Consequently, oil-free compressors tend to be quite simple in construction, with a much lower number of moving parts. This increases the overall reliability of the compressor (fewer parts means fewer parts that can fail) and also makes many oil-free compressors considerably lighter and easier to transport than their conventional counterparts.
A comparatively small number of parts also makes oil-free air compressors quicker and easier to manufacture, and they are subsequently significantly cheaper than most oiled compressors available for sale. However, as you will see below, more expensive oiled compressors can be a more sensible long-term investment.
What are the disadvantages of oil-free compressors?
Oil-free compressors are only capable of functioning for as long as their pre-applied lubricants remain effective, and while most oil-free compressors are equipped with tough lubricants capable of standing up to heavy work without perishing, eventually the lubricants will begin to wear out. Since lubricant cannot be reapplied, the compressor is essentially beyond repair at this point and will need be replaced. Oiled compressors can, therefore, be a more economical solution if you expect your compressor to see heavy use.
The design constraints of oil-free air compressors mean that they tend to be noisier than oiled models, and some high-power models may be far too loud to use indoors safely. These noise levels will increase towards the end of the oil-free compressor's life as its lubricants begin to break down, and are a good indication of when your compressor will need to be replaced.