Compressor for DIY use. Oil or Oil Free?

[Jim Chisholm]

I'm considering a 2hp 25l compressor. Should it be oil or oil-free?

It would be used for tyre inflate, and tools for car restoration, fence and shed construction and spraying. Some tools seem to need oiling for maintenance, and clearly others, especially spraying must be oil free. Some say that oil free are more noisy and less reliable, yet I don't see air line filters to clearly remove all oil (I'd expect something with replaceable elements). Looking at pictures and specs, it looks as though many small machines from different suppliers are identical apart from branding. The cost of the tools will almost certainly exceed the cost of the compressor, hence I don't wish to "Spoil the ship for a ha'pworth of tar"

Help!

Jim

[Nightjar]

Oil free is a relative concept. For most 'oil free' applications, simply removing liquid oil and oil in aerosol form is sufficient. An ordinary water filter will also remove any liquid oil and a coalescing filter will take out the aerosol oil. It is only when you get to things like breathing air that you need to get every last bit of oil vapour out.

You may find this Norgren document useful:

If you can afford it, I would strongly recommend a Hydrovane compressor.

IME they are very reliable and, being rotary, relatively quiet - I used to have them in the factory work areas, which I couldn't have done with a reciprocating compressor.

Colin Bignell

[Jim Chisholm]

I was thinking of something 10% of that price... certainly can't stretch to two grand!

[Nightjar]

I did say if you can afford it :-) You could look at some of the second hand ones on ebay.

Either way, I would go for a conventional compressor and treating the air that comes out to remove the oil. The air is likely to be cleaner that way than if you use an oil free compressor with no post treatment.

Colin Bignell

[robgraham]

I would suggest that some homework needs to be done to be sure that the tan k size / compressor power you get can cope with the tasks you are expecting the machine to do. Some compressed air tools are very greedy on air and a 25l tank will ran 'flat' pretty quickly.

Rob

[Grimly Curmudgeon]

Whatever you do, drain the bugger religiously...

[fred]

You'll also need to keep an idea in mind of intended use. Some air tools need a high c.f.m.(or free air delivered) rate which the majority of small compressors won't achieve.

They are noisy buggers. A most irritating noise to my ears.

[Adrian]

Umm, I've just read through that thread, and whilst rust from condensate that wasn't drained was suggested, it was quickly poo-pooed, with the end consensus being either over-pressure or a flammable mixture being compressed.

[Rick Hughes]

I have an 'oil' compressor and use it with a water separator & oiler for use with any power tools. For paint spraying I use the water separator, disconnect the oiler and add a 5 micron filter

Important if you want to spray is the volume of air it can shift, most useful spray guns are HVLP and you need a fair amount of capacity. (11 cu/ft min)

I bought a portable unit as I need to use it at various locations (30 Litre unit) ... I needed high pressure for nail guns so made sure it was a 10bar unit.

It is an 8.7 cu/ft per min (sorry about mixed imperial & metric) for spraying needed a bit more than that ... so I supplement my compressor by connecting up a 2nd 30 Litre receiver so I have twice the reserve. Let them both fill to 10bar and more than enough for spraying then.

Neighbour uses an old diving cylinder .. as his spare receiver ... usually find them for free at local recycling sites, dumped once out of test.

[Huge]

Bizarre, given it's cheaper to get them tested than to replace them.

[Adam Aglionby]

Think oil is generally considered a bit more reliable, put a filter seperator on it for spraying.

Spraying car paint is fine if your not trying to paint a whole car at once, then the lack of sustained airflow can be a problem.

Most air tools function fine on a small tank, inflater, ratchet, impact windy gun,air chisel, needle scaler, metal nibbler though sanders and big grinders are air hogs but both have electric equivalents.

Oiling tools can be done with a drop or 2 into the air inlet before use , unless you have them whirling 8 hours a day on a production line when an inline oiler might help.