What to look for in an air compressor.

**Swarfing** · 19-04-2013

air compressor | eBay

First one i came to and you can get them cheaper like i say. Don't worry about 3 phase either as you can run it with a VFD

**John S** · 19-04-2013

If you go for a Hydrovane go for a 5 series, plenty big enough and many are on single phase.Search on ebay for hydrovane 501

Don't buy the tripod mounted ones, get the tank mounted.

They are different, the tripod mounted ones unload the compressor when pressure is reached so the motor runs all the while.

The tank mounted units have pressure switches.

I run two 5 series side by side but only run one at a time however both tanks are coupled so I have plenty of air.

**Iwant1** · 19-04-2013

John could we get a bit more real life usage of the hydrovane 5 series.

I've been looking on ebay for some time now and they do come up often for around £300, which I don't mind paying, but when I read the specs of the 501, it only produces 4.2 cfm FAD. Seems crap against say a £300 secondhand 150ltr Sealey/Abac/Clarke with 14cfm. Would the 501 easily allow for some spray painting, blasting, sanding. Could it even be used for blowing chips away.

Feel like I have to look at a big 3 phase hydorvanes to get any where near descent Ccfm. But then these are a huge step up, with ratings of 20+ cfm.

Are the hydrovane and regular compressor cfm's not comparable?

Cheers Adil

**John S** · 19-04-2013

You have basically answerd your own question when you state 4.2cfm FAD which means Free Air delivery. because they don't have a swept volume like a piston compressor they have to state what they put out.

CFM means sod all, CFM is the swept volume x revs in one minute and doesn't take into account valves opening and closing which is when the proper work is done.

Read this.

The "power" of an air compressor

**m_c** · 19-04-2013

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**John S** · 19-04-2013

What you have to do with the tankless units is put them on a tank and run them up to see what pressure they spit out before they unload.

Then fit a pressure switch, machine mart are reasonable for these, and set it for 10 pounds less than the test pressure, this way they perform the same as the tank model.