I finally picked up a regulator and moisture trap today. Hooked it up and everything seems fine. On to my questions. When I turn on my compressor the regulator read 30 psi. So I turned the switch, to go to a lower pressure but the gauge did not move. Only until I pressed on the AB trigger did the pressure drop. Is this thing broken or is that the way it works? Also I was wondering what psi range should my regulator be set to for spraying broad coverage, such as a car body. and what should it be at for fine detail? Thaks.
Regulators will do that when dropping the pressure down because they work on air pressure present in the gauge and to drop that pressure the gauge needs some air released. When you increase the pressure though, the needle on the regulator should go up immediately.
For general coverage on something like a car body or an aircraft I use around 20-25 psi myself as the lower pressures don’t put out the volume well enough.
For fine spraying I would work in the 10-15 psi range as that allows for a fine line with little overspray.
As Mike said, that is perfectly normal. If you already had your airbrush and hose hooked up there was air in the hose under the pressure the regulator was set at. Lowering the regulator setting does not bleed the air already in the regulator and hose, so it would stay there under the initial pressure setting until it is bled out.
Also, when you first air up the compressor the regulator may show a slightly higher than set pressure. It will also bleed down as soon as you release a little air.
One question: once the pressure drops to the regulated pressure after the initial squirt, does it stay down there or does it go back up to the tank pressure? A proper regulator will keep the pressure down. Some very cheap regulators won’t do this and it results in an overly high-pressure spray when the trigger is first pressed.
They shouldn’t do that. That’s the whole purpose of a regulator, to isolate the high-pressure side from the low-pressure side. The only way the low and high sides should be the same is if 1) The regulator is broken or 2) The regulator is set wide open.
Thanks for the info. Hope I don’t run into one of those! My compressor is a 150psi compressor. I’d really hate to see that at my airbrush [:)]
limd21, Once I press the trigger the pressure drops and stays at the PSI I set it to for the duration of the time Im’ holding the trigger. Once I let off the trigger the pressure goes back up. Hope I made that clear enough. Im not sure if the regulator is a cheap one, it is one of the Campbell Hausfield ones.
I guess I will throw in a fe more questions while im here. These dont have anything to do with the regulator, but with using my airbrush. Im completely new to using an Ab so these are probably basic questions. I was wondering what what the knurled knob does at the end of the needle. And also the same for the bigger piece that screws into the main body part of the AB. I thought about buying the book How to Use an Airbrush, that was put out by Kalmbach. I s this a very good book to help me learn more about my AB and how to use it? Thanks
Click on the ‘Catalog’ link and on page 1 there is a cutaway photo of the internals of an airbrush.
I don’t know much about that book you mentioned, but you could learn all you need right here on this forum. There are many years of combined airbrushing experience on this forum. [;)]
How much does the pressure go back up when you let off the trigger? Mine sits idle at about 3 psi higher than when I am spraying, and that’s pretty normal. If it’s much more than that something may be wrong with it.
Cambpell-Hausfield makes good regulators, I have a CH compressor and regulator. They are designed for the higher end of the pressure spectrum though, say in the 90 psi range, and when you get down around 15 psi they act a little strange. As long as the pressure stays pretty consistant when you are spraying and as long as there isn’t a big difference between the pressure when you are spraying and when you aren’t, don’t worry about it.
Im not exactly sure how much higher the pressure goes back up, i will have to check it out tomorrow. i could be completely wrong but does it really matter what the pressure is at when im not spraying, just as long as it drops to the desired PSI when I press on the trigger.
Ah come on Scott. You are making me blush my friend, [:I]
I appreciate your confidence in me but I am still learning just like we all are and I learn just as much from the good folks on this forum as you do. [;)]
The day I quit learning is the day I die because life is a continual learning experience. The difference between you and a few others and the rest of us is in our positions on the learning curve [:)]
Yes - a few psi higher than when spraying is normal, but if it goes back up to tank pressure it is either faulty or it’s one of those really cheap “regulators” that I’ve run across from time to time. These are not really regulators, in my book, but more of a simple restriction valve. They’re ok for things like shop tools where pressures aren’t super critical, but simply don’t work for most painting.
I’ll bet you got an air tool regulator. I’ve got one (for my air tools), it’s basically an air restricting valve. I tried to use it with an airbrush, but I just went out an bought a real regulator from Harbor Freight. It came with a moisture trap, and I was able to mount it on my wall. It was about $20, IIRC.
i checked it out, and once I let off the trigger the pressure goes back up to tank pressure. I guess i could take it back and get my money in return and buy a different regulator, but it worked fine as long as I triggered the airflow and allowed the PSI to drop and then draw back for paint flow.
The problem is that you are showing tank pressure all the way to the air valve in your air brush. How much pressure is in your tank? I don’t know what the airbrush valves or hoses are rated at but I’d be surprised if it’s over 90 psi. MikeV would probably know. If you have pretty high pressure in your tank, say 100psi or more, you may be exceeding the rating for the valve and/or hose.