Air compressor for spray painting?How many hp for a good job

[meta]

Hi everyone,

Basically, i'm about to get a spray job done on my car and i need to find out for my mate which air compressor will be capable of flowing 2.2 bars/ 33psi...will a 5hp compressor be able to take the load?

thanks meta

[Mr Morlock]

The subject of compressors comes down to what you want to do. Spray painting does not use a lot of air. Comparo's need to be done on what the compressor delivers in the way of air- and then look at the guns output. It is still odd that many of the specs thrown around are a mix of imperial and metric. A motor to drive the compressor and provide enough air does not require 5hp- a 2hp or even less should be sufficient to provide enough air for spraying. If you are buying a compressor and you want to use air tools like die grinders then a larger unit makes sense. I can tell you that in the old language 8cfm would be enough- but ask either an auto paint specialist or someone familiar with the performance of the equipment and your needs.

[StanTheMan]

2hp is plenty if you have a 50L tank

2.5 is better though because it mean the compressor has to work less. If a compressor has to work less that means there is less condensation.

whatever compressor you do use. make sure you know all about removing moisture.

I did a paintjob. I thought I did everything by the book. A huge effort was put in by myself & bigdog. But we somehow ended up with moisture bubbles inn the paintwork.


a lot of stuff can go wrong. The compressor is just one of many things which can make or break a good paint job.

[StanTheMan]

and on a side note.

If someone charges you $8K for a back to metal paint job. Its worth every cent.

[baldas]

From memory I think flow rate is also important ie litres/minute. Some High Volume Low Pressure (HVLP) guns use a lot of air. The size of your air lines also becomes important - 90 to 100 litres per minute.

I have to agree with Stan - doing it yourself (even with help) still requires lots of time and effort - spray painting is the quick part - there are many traps just waiting to trip you up.

[meta]

Hey hey everyone,

thanks for the replies

I'm getting a front bar and a right guard sprayed up, moisture won't be a problem we have that sorted as well as the spray guns, my mates a professional spray painter, so everything is sweet there, however, he hasn't had much experience with air compressors unfortunately, from what he's said about other backyard jobs, he mentioned that his main concern was the constant speed/flow of the paint, although he could probably spray with a 2.5hp compressor, the rate at which it was coming was slow and painful lol on top of that he had to let the compressor rest at some point (or at least that's what he said).

Either way, after a chat with him last night, he mentioned although about 33psi was needed for a decent spray, it was more like 40psi to keep it at a constant pressure and rate, so with that in mind, i'm assuming a 5hp might not cut it lol

Thanks again everyone for your help

meta

[bigdog]

2.75hp single phase with 50 litre tank will do it comfortably. The compressor we borrowed to do Stan's job was old and let moisture in past the trap. I now have a new stoopidcheap 2.75 with double traps and a trap on the gun and it all works just fine. About $500 though...

[Mr Morlock]

here is a spec for a unit 2.2hp unit which delivered at 100 psi ( 684kpa) 240lpm and the tank size was 55litres. 5hp as already stated is more than enough.

[mr_rotary]

Instead of buying one, can't you hire one out that will do the job better than one you could buy? If your mate is doing it, can't he do it after hours at his workplace where he has the right equipment?

[bigdog]

As we found out old compressors are risky. Most hire company compressors are used to run air tools, not paint, and thus can't be guaranteed to be any good. Have a look at the setup in a proper paint shop, they go to extreme lengths to remove contamination from the air supply.

[kazjim]

Just my 2c ....

I did a spray job for a mate with a de-seamed Mini ....

I used a SuperCrap Direct Drive 2Hp unit and 2 driers - 30' hose

The gun was a pretty schmick gravity feed one, and as long as we took our time and layered the paint up nice and fine it was a great setup ...

All in all it was about 4 days spraying and 4 weeks preparation !

Edit--> Found some pics ....








Check the weather outside, if the humidity is high, give it a miss and have a beer instead ....

Good luck
J