Can Someone Explain Compressors To Me Please?

[Chris England]

Morning All B)

I am a weekend warrior who wants to buy a compressor and some air tools as I think it will save me oodles of time when I am tinkering away, I had a compressor in the past and it was great for inflating tyres, doing a bit of spraying but with an impact gun it was useless. The various numbers that describe a compressor I find incredibly confusing because I have no idea what they mean PSI, CFM tank size what is it that tells you how powerful a compressor is going to run?

I do not want to spend a fortune as this is a hobby not my trade but I do want something that is all round capable, I have been looking at this one on Ebay:

This One

Will this be a capable machine? It’s forst job will be a crank shaft pulley nut on a Citroen Picasso 2.0 HDI which I have been advised are a pain to undo and a compressor makes it a million times easier, I do not want to spend the money to find it will not budge it!

Also I am presuming the Impact gun will also make a difference the one I am looking at is:

This One

This this seem like a good tool?

Thanks in advance

Chris

Topic

[Ryan Wofford]

PSI (pounds of pressure per square inch) is how much pressure the tank can hold, if you have a high psi tank but a low CFM (Cubic feet a minute, or volume)it will take a long time to get filled but once filled it will have a lot of pressure. however a high CFM compressor with a low PSI tank will tank very little time to fill up however the low PSI will make it less compatible with everything else (impacts usually require at least 100 PSI to perform correctly) try to find a decent balance between the two and it should work fine. I can’t look at the ebay things sadly due to the restricted internet here. I can look at them when I’m home

[James O’Hara]

You need to know what the psi is at that 14cfm. Aka if it is 14cfm at 10psi and only 2cfm at 90psi its pretty useless. Also I do not know these brand but you are in the UK not my fortay.

A couple threads you might want to read up on.

http://www.ericthecarguy.com/kunena/15-Technicians-Only/55499-so-you-want-are-going-to-be-a-mechanic-technician#123559

http://www.ericthecarguy.com/kunena/11-Tool-Talk/55609-3-8-impact-or-power-probe#123408

http://www.ericthecarguy.com/kunena/11-Tool-Talk/57079-new-air-tools#131665

http://www.ericthecarguy.com/kunena/11-Tool-Talk/55641-air-hose-diameter-questions

Once you look at those I am pretty sure almost everyone one of your questions will be answered.

[zero]

Based on what most air tools say they require for maximum output, I feel it safe to assume that you want a compressor capable of at least 5-6cfm@ 100psi. Impact guns typically operate in the range of 5cfm.

A quick Google of the compressor reveals that it operates at 240v (LINK). I’m not sure what household current is in the UK (assuming because of pounds used in ebay link) but in North America that would indicate you need a special circuit hooked up to run it as normal household voltage is 110.

The Impact honestly looks like one of the models that is commonly re-branded as store brands. they work, not as well as a premium brand but obviously way cheaper.

[Nick Warner]

Another thing to keep in mind is hose diameter. You can have the biggest compressor in the world but if you just hook a 1/4″ air hose up your impact will fall on its face and be worthless. Hose sizes are listed by inner diameter, as some have thicker walls than others do. Most 1/2″ drive guns need a minimum of 3/8″ ID hose (10mm). They do even better with a 1/2″ (12.7mm) ID hose but sometimes its not easy to get such a big hose in tight spots. Realize the pressure the gun needs is while it is running, not static. Say you get your pressure up to 125psi, which is the normal cut-off pressure of a regular household compressor. But you need enough flow through the hose to keep pressure maintained while operating the tool. If you have a small air tank, you will suck the pressure down very fast and only get a second or two of good power before it is useless.

Keep an eye on local for sale ads. You might get a good deal on a used one. Look for one that is belt drive, direct drives are just deafening to be anywhere near. Turn it on at night and you WILL have neighbors that no longer like you.The bigger the tank the better. Once you have an impact you’ll end up getting air ratchets and definitely a die grinder and the extra volume will allow longer operation at power before having to wait for the pressure to come back up.

I believe your house power is already 220v, but look at the specs for amp draw to make sure you have a circuit with the right plug in and wiring rated for the current. Bigger compressors need a plug like an electric oven or dryer take.

[Jon Hart]

Wolf compressors are just awful I’ll start off with that wouldn’t touch them.

The size and type of compressor really depend on what you’re planning to do with it Ideally you want a 100L tank with about 3hp but you could make do with 50L but you’ll have to wait around for the tank to fill. I’m from the Uk so I can help you out with Decent home tool brands

http://www.sgs-engineering.com/air-compressors/50-litre/sc50h-50-litre-high-flow-air-compressor

http://www.sipuk.co.uk/sip-airline-vdx-50-cm3-50l-direct-drive-air-compressor-12-6cfm.html

You wont get anything with more than a 3hp motor and make sure they run of a standard 13amp plug (you’ll probably want to run it on it’s own circuit which will mean a spare breaker slot or a small garage consumer unit.

You can go bigger and wire in a 20 amp breaker but probably over kill for home use unless you want to do HVLP spraying.

As for Air impact wrenches

http://www.sipuk.co.uk/sip-07336-1-2-impact-wrench-825-ft-lbs-torque-8-0-cfm.html

http://www.sealey.co.uk/PLPageBuilder.asp?gotonode=ViewProduct&method=mViewProduct&productid=17439&productdescription=&productcode=&category=12&catgroup=210&catmicrogroup=1003&analysiscode=&requiredresults=16

Both of those do exactly what you need

If you need any help with tools or or tooling feel free to drop me a line.

[Matthew Ross]

Do you have 120v or 240v outlets in your garage?

[Jon Hart]

240v single phase for domestic 400v 3 phase for commercial.

[Lorrin Barth]

When I bought my first compressor I brought it home, plugged it in, turned it on and found myself standing in the dark. The motor was wired for 110 volts but could be switched to 220 volts which is what it really needed. Second job – completely rewire the shop for 220 volts.

Three horsepower is overkill for a garage shop. I have a nice compressor which is 1.9 hp and is capable of everything. It pulls about 7.5 amps continuous at 220 volts but much more at starting.

I’d suggest an oil lubricated belt driven compressor.

[Author]

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