Compressor advice please

Got a whole lot of tins of Dinitrol cavity wax (ML) and black underbody wax (4941) along with a spray gun and lance. Next step is to get hold of an air compressor.

I have never owned or used an air compressor before, hence asking for some advice on here. First issue is do I buy one, hire one or try and borrow one. I am undecided at the moment, I certainly don't want to buy one just for this one job so am trying to think of anything else I could use it for in the future.

Next question is should I trust Dinitrol's min requirement of 6 Bar or 90psi operating pressure & 4 CFM or would I be better served getting something much more powerful?

OAKLEYPILOT:

What projects are you planning on in the future? Sometimes, it's better to buy. Renting can be expensive at times.
I bought one for myself and then one for my Father. Glad I did. Air wrenches, drills, nailers, sanders, ex cetera, ex cetera.
Get as big as you can afford, with a large tank (pump doesn't run as often.)
Even if you don't use it too much, it is wonderful when you get up in the wee hours and find a flat tyre.

Les

When you decide on a compressor do a bit of research first and remember that there is a difference between a volume of air at working pressure (e.g. 90 psig) and compressor displacement. Put simply a compressor that delivers 10 cfm at 90 psig is shifting twice as much air as one delivering 10cfm at 45psig. (look up Boyle's law).

There is no proper standard for describing the output or capacity of a compressor or for the actual requirements of a power tool.

Unscrupulous? vendors will tend to pick a value (with inconsistent references) that makes their tool look good i.e. big numbers for compressors and small numbers for tools. (Machine mart do this with some of their gear)

Using this understanding, a compressor that's described as 10CFM FAD (free air delivery) will not drive an air tool that requires 10CFM at 90psi because at 90psi (6bar) the compressor is only making 1.7CFM (at the working pressure). This is why (most) compressors have a tank, which provides a reservoir of air at a higher pressure that the consumer tool requires. So you can use a tool at a higher consumption rate than the compressors production rate for a period proportional to the size of the tank and the difference between storage pressure and tool pressure requirement.

When you make your choice make sure you understand what you are buying and if the vendor you are talking to can't tell you what you need to know walk away and talk to someone who knows his stuff.

I'm not trying to tell you how to suck eggs but it is a fairly complex subject to get your head around if it's not your thing and it's easy to buy the wrong piece of kit and be disappointed.

So after my previous ramblings, my recommendation for a compressor would be an Atlas Copco ER9. 2 stage reciprocating compressor, 3200CFM with a 600HP, 3.3KV, 3ph motor. Only available second hand now but spares are available and you would need to source your own air receiver.
I used to look after 4 of them (amongst others) where I used to work. Awesome piece of kit much better than modern stuff if not quite so energy efficient. (picture from the web)

Make sure yor tank is a minimum of 25 litres this will do most DIY Requirements.

I bought a cheapie of eBay, mainly to run a sandblasting cabinet, and just had to order some spares for it. I was pleasantly surprised that spares were a: available and b: a reasonable price.

It gets far more use than I ever thought it would and I've got to hold my hands up and say it was my fault it needed fixing, me and my mate both thought the other was checking the oil :doh: the upshot of which one of the big ends seized. New pistons, rings, conrods and crankshaft cost me £35 which I thought was reasonable.

Perfectly adequate for light/medium use.

Thanks all for your advice, going to start trying to find a second hand one.

waldershelf said:

So after my previous ramblings, my recommendation for a compressor would be an Atlas Copco ER9. 2 stage reciprocating compressor, 3200CFM with a 600HP, 3.3KV, 3ph motor. Only available second hand now but spares are available and you would need to source your own air receiver.
I used to look after 4 of them (amongst others) where I used to work. Awesome piece of kit much better than modern stuff if not quite so energy efficient. (picture from the web)

Click to expand...

Heh, I will try explaining to the wife why I need to fill my entire garage with a vast industrial compressor.

waldershelf said:

So after my previous ramblings, my recommendation for a compressor would be an Atlas Copco ER9. 2 stage reciprocating compressor, 3200CFM with a 600HP, 3.3KV, 3ph motor. Only available second hand now but spares are available and you would need to source your own air receiver.
I used to look after 4 of them (amongst others) where I used to work. Awesome piece of kit much better than modern stuff if not quite so energy efficient. (picture from the web)

Click to expand...

:hysterically_laughi

OakleyPilot said:

Heh, I will try explaining to the wife why I need to fill my entire garage with a vast industrial compressor.

Click to expand...

Go on, Go on, Go on, You know you want to

When you do send me a PM with "convincing the wife" guidance, I need it, nearly 32 years wed' and I still don't have a clue.

Oh, and unless you have a "HUGE" garage it wouldn't fit.