Do you guys know what is the right hp for a compressor to run a spray gun ? I currently own a .5hp compressor with 25litre drum.
I found a new .75hp silent compressor with 50 litre drum and was thinking of buying it …because it is silent…and i like silence. But i am not sure if it enough . Any thoughts ?
The hp doesn´t say much, it´s the capicity you have to look at. I´ve a 2,5 kw compressor and even that is to less for a satajet spray gun. To give an exemple of the air useage of my guns RP: 285 l/min at 2 bar; HVLP: 430 l/min at 2 bar.
Also keep in mind that compressors are almost all the time advertised with the air that goes in and not out.
It doesn’t take much power to run a spray gun. With compressors in general, I look for the output psi. Most spray guns and air tools in general will have a stated pressure where they are optimal.
The spray gun I am currently using runs on just 30 psi. I can run it from the exhaust output on my vacuum pump.
Larger compressors can output 250 psi or more so, to run something like a spray gun, you would need an additional regulator to reduce the output pressure. In other words, it is highly unlikely you run into issues from a lack of power with any shop compressor.
If you can find one, I would go for something with a pressure control that allows you to set it for anywhere between 15psi and 150 psi. That would save you have to buy a separate regulator. If you buy a separate reg, go for an adjustable one.
If you check the stated operating pressure of your air tools, you should be able to see the max you will need easily enough.
Power is not the problem with spray painting, it is primarily flow rate and somewhat less importantly, tank size.
Any compressor will be able to pump 30psi, in fact most compressors will be able to pump 150+psi. The question is how long it can sustain it for. A 0.5hp pump is likely only going to be flowing around 80L, which means if you are spraying anything larger than say a helmet (random object), you might find the pressure at your spray gun starts off fine but by the time you have finished spraying a coat it has dropped to 10psi. In a lot of cases this won’t actually matter so much, as most paint will still atomise at 10psi, but if you have an eye for detail then you will notice the difference in orange peel as you look at the finish. It certainly wouldn’t be ideal for spraying a car panel.
The other issue is tank size, but this isn’t really a huge problem, it more determines how often the compressor is running. Spray painting will empty a 50L tank virtually straight away, so your pump will just always be running. As long as it has the flow rate to keep up with the gun, then this won’t effect what you are doing, so the concern is more about noise and wear on the compressor.
To put it in realistic terms, if you are spray painting small items like interior car trims, then a small compressor will probably be fine if you can put up with the noise of it constantly running. If you are doing bigger pieces like individual car panels, you will want a bigger pump. Something around the 200L mark would be ideal (so probably around 2.5hp and 120L tank, but this can vary). And if you are trying to spray paint a full car, then you should really be looking beyond single phase power capabilities. At the very very least you will need single phase 15A power, but a three phase compressor would definitely give you a better finish. So it depends what you need to achieve.