Oil carryover in the compressed air line is an issue for some portable compressors particularly if the compressor is oil lubed, and very much particularly if the compressor is older, as the cylinder seals tend to leak more in older compressors.
If this is critical problem for what you are doing with compressed air, then you will want to add a coalescing filter downstream of your compressor, and as close to the point of use as possible, to remove oil from the air stream.
To increase the life of the coalescent element in the oil-removing filter, install a 5 Micron general purpose compressed air filter upstream from the coalescent filter. This general purpose filter will remove free water and larger (relatively speaking) particulates from the air stream, freeing the coalescent element to work on oil removal and helping this more expensive filter element to last longer between changes.
If your compressor duty cycle is high - as in you are using the compressor all day - you might also add a 40 Micron general purpose filter upstream from the 5 Micron unit. This will extend the life of both the 5 micron and coalescent filter elements.
Preparing compressed air for use in any application is a continuum. You keep adding equipment to the compressed air stream to condition the compressed air to the level the equipment needs.
That may mean that you have to throw quite a bit of money at it, others can get by with just a general purpose 40 micron filter. The application for compressed air dictates the level of treatment.
Sometimes the air-using equipment demands a larger compressor, and there are a variety that are still portable compressors, but not carry. These portable air compressors ar on wheels.
Some compressors are dual voltage, and can be wired to run on a 220 Volt circuit and a 120 volt circuit. Make sure you are comfortable with rewiring the compressor motor to change voltage should it be necessary. Not sure? Be safe! Leave electrical work to persons that are qualified!
When powered by 220 volts, compressors are more efficient and have greater capacity than when supplied by 120 VAC. The air compressor is a converter, turning electrical power into stored compressed air energy. A 120 volt circuit has less energy available for conversion to compressed air energy than does the 220 volt circuit. The 220 can generate higher flows of compressed air from the appropriately sized compressor.
Portability of compressors knows no bounds! Compressors are routinely flown into to remote sites all over the world.
How often do you drive down a highway and see a work crew using a portable compressor on road construction? Since construction usually slows traffic (almost always when you are in a hurry and trying to get somewhere quickly it seems) you will have the opportunity to check out the portable compressor as you drive by.
The compressor in the latest photo is a rotary screw, continuous run, with a 100% duty cycle, and is powered by diesel fuel.
I hope that last couple of pages provided useful information for you. Still have a question? Just ASK.