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Hi all. I purchased a Bartsharp AC02 air compressor (fairly bog standard tanked compressor). I airbrush anywhere between 15-30 psi and get around 15 seconds before the compressor kicks in. I was under the impression that it would switch off after topping up the tank and obviously turn on again intermittently as required. However if I continue to use the airbrush the compressor is constantly working unless I stop for a minute or two. Is this normal? Any help/advice much appreciated.

That seems like a solid compressor and the tank is big enough for airbrush work. However, the tank max psi is only 49, which is not that high, so hence you do not have to let much air out of the tank before it needs to replenish. Most airbrush compressors are like this, whereas air tool compressors will have a 120 or 150 psi and that allows a whole lot more air to be pushed into the tank and running an airbrush for quite a while before it needs to kick in and fill the tank again.

So, nothing wrong with what your compressor is doing. Some checks would be to make sure you do not have any leaks and see if you can keep your regulator pressure down in the 20-25 range to not let quite so much air out. One other check is to find out from the manufacturer what is the psi that trips the compressor on and is there any way to lower that - maybe it comes on when tank pressure is 45 and maybe you can set it to 35.

The only other option if this really bothers you is to connect another tank so you have a greater volume of compressed air at your disposal; however, at that point you may just want to pick up a cheap air tool compressor that has a much higher psi capacity.

That's fine.

Just check you're not running your PSI excessively high, check that your PSI isn't dropping when the compressor kicks in, and if the compressor is running a lot it might be worth adding a moisture trap after your air hose just before the brush, as a hot compressor will mean hotter air which can mean moisture being a bigger problem.

great info from the 2 previous posters. thank you.

Thank you both for the helpful replies. Do the more expensive compressors tend to work the same? (a sparmax for example)

Pretty much all work the same, but the specs may differ, like a higher psi capability in the tank, tank and regulator psi settings, SCFM volume - how much air and how fast it can replenish the tank, etc.

Tommytomtom wrote:
Thank you both for the helpful replies. Do the more expensive compressors tend to work the same? (a sparmax for example)

Okay, in my previous post I said "That's fine", I probably should have qualified that by saying you should pause occasionally to let the compressor cool down if it's unable to fill the tank while you're using it, as compressors can overheat. It's usually not an issue with miniature painting as we tend to pause occasionally anyway, but if you were painting a full sized car it's not good to run the compressor 100% of the time for hours on end. If it does overheat, it SHOULD turn off by itself, but on my compressor I can hear it get noisier if it starts to get too hot.

Maybe every 20 minutes or so, give the compressor a breather for a few minutes, perhaps when you change colours just take a couple of minutes break.

Compressors have a "duty cycle", which is a percentage of time it can be running without issues. For example, a 90% duty cycle would mean if running for 60 minutes, it should have 6 minutes worth of breaks in that hour where it's not trying to fill the tank. This is usually more of an issue for heavy duty tasks like spraying a car than it is for miniature painting.

Cheaper compressors sometimes won't tell you what is the duty cycle, it may be listed in the user manual, but even if it's not it's best to assume it's not designed to run 100% of the time.

To your question of whether more expensive compressors are the same, yes they are, it's more a function of the tank size and compressor's flow rate at pressure which may be the same between a cheap and expensive one. However better compressors may have higher duty cycles, they may be less prone to getting hot, less noisy, overall better build quality (like my cheap compressor developed a leaky fitting which broke over time and gets noisy as it heats up, maybe a more expensive compressor wouldn't have those issues). If you get into shop compressors, they may change technology (oil vs oil free, belt drive vs direct drive, electric vs petrol) but for hobby compressors the cheap ones are functionally pretty similar to the expensive ones.

AllSeeingSkink - that is useful info about the duty cycle - I had read about those on more commercial compressor specs, but never really knew how that translated - thanks!!!