air compressor

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IFFY100

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Jun 8, 2020
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313
Location
SCOTLAND
Car
Cls 350 cdi 2010 grand edition
Thinking seriously about getting an air compressor. Would like the extra flexibility and would also like to try some spray painting/prep work. Can anyone share experiences or advice in my research please?
 
Volume of air. Pressure is pressure, it's the volume that the thing can deliver that will determine how useful it is to you . Especially in the DIY compressor market.

In my (limited) DIY compressor experience, Iv had the same 9.5 cfm 25 litre for more than 10 years now, Ok for bit's and bobs. But My next one will be no less than 100 Litre 14- 15 cfm twin piston 220V around £450 from Machine Mart etc.

I have a stand alone receiver tank for my compressor and have fitted high volume air lines, but it's just not man enough for air tool use and soon runs out of puff (see what I did there ) Basically just go for the highest cfm that you cam afford.

Before you buy a compressor research the tools you plan to connect it to , their cfm requirements will dictate which compressor you need.
 
Ditto. I've got a 25 litre compressor which is ok for nail guns. But it can't crack wheel nuts or run tools which need a continuous air supply.
 
Once you have had a compressor you will wonder how you managed without it. The 25 litre 1.5hp ones are OK for pumping tyres and use for cleaning off stuff, a 50 litre 2.5hp will just about manage a spray gun but if you are serious about spraying you really need a 100 litre tank and 3hp +
Some of the smaller ones are "oil free" - the bore is teflon coated I think. Personally I would avoid those. The airmaster from machine mart or the SGS range seem to be decent vfm.
Spraying a car to anything like a half decent standard is not easy and needs lots of practice.
 
A friend of mine gave me a compressor years ago, had never used it until last week it works perfectly, i took my air nibbler home from work to cut the top of an oil drum and plugged it in worked the tool with no load on it for about 3 seconds then slowed down so its pretty much useless, so def get the biggest 1 you can afford as this 1 is of no use to me really as i was intending running air tools of it
 
47kg propane bottle will make a good holding tank with a bit of fetling.
 
I'd say 50 litre minimum and one with good pressure and cfm.

However what also is key is the hose you use and the connectors. If you use cheap hose and standard fittings the air is coming through a narrow channel. You'll struggle to crack wheel nuts even if the compressor has the right specs. A 10mm dia hose and extra flow PCL connectors make all the difference - even the tightest wheel nuts will fly off. You could even choose to do them up as tight as KwikFit......
 
I have an old Wolf compressor, a Dakota 100, bought from one of the less famed sellers on the internet though it's been very reliable up to date.

The 100 refers to the tank capacity (100 litres) which, retrospectively, I should have increased slightly and gone for the 150. It's a 3HP single phase motor giving up to 150psi, though it's set to 90 here as that's ample for me. It came supplied with a standard 13amp plug though this was soon changed to a 16amp due to the initial draw when the motor kicks in.

It has an air displacement figure of 14CFM though this is not as important as people (especially sales assistants) try to make out. The figure you need is Free Air Delivery, which is usually about 2/3 of the CFM figure. This will give you a much more accurate figure to base your needs on. There's a simple explanation on THIS PAGE regarding FAD.

Mine isn't used very often now, though it has the ability to run a dual action sander for long periods along with other smaller stuff at the same time. It has no issues cracking wheel bolts though that's probably down to the US Pro 8513 gun rather that the compressor itself, as previous guns used to struggle.

In summary, work out exactly what you need to run off it, calculate the FAD each tool uses, also will they be used together or one at a time, once you have a figure, double it and you won't be far off. :) Oh, and go for the biggest receiver you can, it's always handy to have a bit of air in reserve.
 
I'd say 50 litre minimum and one with good pressure and cfm.

However what also is key is the hose you use and the connectors. If you use cheap hose and standard fittings the air is coming through a narrow channel. You'll struggle to crack wheel nuts even if the compressor has the right specs. A 10mm dia hose and extra flow PCL connectors make all the difference - even the tightest wheel nuts will fly off. You could even choose to do them up as tight as KwikFit......
This is something I've seen elsewhere - that narrow and restrictive fittings and hoses castrate the compressor's efforts due to the pressure drop across them. Guys I know (on-line) have measured the actual drops and they are pretty hideous. Gauge on the tank is reading high but only a fraction of that is getting to the tool. Maximising the flow between tank and tool is, as you say, key.

NB. Doubling the internal diameter of any hose or fitting quadruples its internal flow area. Eliminate any superfluous fittings (especially 90 degree elbows) and minimise the length of hose.
 
If you're going to use it for paint spraying, don't forget you'll need an oil / water separator and pressure regulator. As others have already said, receiver volume, CFM and FAD ratings are all important, as are quality low-loss couplings.

It would be worth talking with a local compressed air specialist. They may be aware of someone decommissioning a smaller industrial unit that would potentially give you much more bang for the buck than any of the more generic "hobbyist" solutions available from the high-street tool suppliers, and they would certainly be in a position to give good advice about how to size something for your needs.

Also something to remember is that compressed air is a particularly expensive commodity to produce in terms of power consumption. You may need to consider upgrading an existing power outlet or providing a dedicated power line if you go for a higher capability compressor.
 
My 25 litre Bostich compressor needs a "full" power supply. Was trying to run it at the end of 3 extension leads & it wouldn't kick into life. Seems like it is sensitive to a voltage drop
 

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