I read that 2K spray guns require a certain high volume of air to function properly & give good results.

Would a small 2.5HP direct drive 40-50L portable compressor run them well once it's tank is full? Or is there an issue of not enough air coming out of the hose at any given time?

I wan't to paint some small bike frames & small a4 sized boxes for example.

Thanks

2K spray gun? No such thing, mate.

HVLP (high volume, low pressure) guns are generally the biggest air hogs but that depends on things like gun brand, model and tip size.

The old HP guns used a bit, too, but needed the high pressure to atomise so were somewhat wasteful.

Best choice is an RP (reduced pressure) gun and a lot of these will be very economical with the air supply, as they are with paint.

Those compressors you're looking at won't supply enough air for a full size gun. However, for what you're doing you don't need, or want a full size gun. Devilbiss make a smaller gun, SRiPro, which only uses 3.5cfm, well within the capacity of that compressor. Bit exxy, though. More mid-range would be the Star SMV1000F-132G which is my gun of choice for those kinds of jobs. At under $200 they're economical too with good parts backup here as well. Their advantage is that the pot is side mounted, rather than top, and can rotate 360 degrees. Ideal for things like bike frames where you're painting at every angle.

Hi, that Star SMV1000F-132G looks good, curious as it requires around 250l/m, while this is a 180l/m compressor.

Once the tank of air is full, could I spray the whole bike area without any troubles in atomising & quality? Or should I just stick with the small 3.5cfm?


Thanks

Depends. What kind of duty cycle the compressor is rated for, and what kind of paint quality you are willing to accept.
I would probably go for the smaller spray gun simply because a larger gun like the Star will likely give you more overspray (larger pattern) unless you dial it way back.
Also, if you paint to the point where the compressor is trying to supply air and refill the tank because it is empty, you could end up with color shift or other problems.
Ideally, if you are painting a lot, you would upsize your compressor. In the absence of that option, go with the gun best suited to work with that compressor.

Would that wide pattern be good for a4 sized objects?

thanks

It will work, but it might be overkill. A4 is roughly US letter size (8" x 11").
I think you really need something more closely related to a touch-up gun. The SRI-Pro would fit the bill nicely, IMHO. And it would work well with your smaller compressor.