My goal here and in the following blogs I post will always be to try and bring useful information to everyone from the Do-it-yourselfers to the guys doing this for a living. Now I'm aware that on every topic I cover there could be volumes of more information written but for the sake of simplicity I want to stay brief and cover the essentials.
In my years in the field I have seen some crazy stuff, don't believe me try this one on for size. I once saw a guy at a bodyshop I believe it was in Columbia somewhere using a combination of a lawnmower engine and a vehicle A/C compressor to produce enough air to spray paint a vehicle. Wish I knew years earlier I'd be writing a Blog I sure would have snapped a picture of that setup. Human ingenuity it's a beautiful thing.
So to the point "Enough" air, the topic I'm going to cover is air Volume. There are many issues and contaminants that will ruin a paint job but one of the biggest problems that won't go away unless you do it right from the beginning is your shops air supply lines. You can add expensive and sophisticated filters along the way to solve water and moisture problems in your paint, but the quantity of air just won't be there if you don't get it right when you lay down your air lines.
There are diagrams and design ideas out there from companies like Devilbiss and Binks, they will show you the right diameter to use from the air source (compressor) depending on how far you are going with the air lines. Along the way you can add water traps that won't cost you much more in plumbing and will save you hundreds of headaches and dollars in filters and paint problems.
This problem isn't just for the big boys at the shops. If you are a hobbyist with a portable compressor and are using any type of High Volume spray gun or air tool that consumes a lot of air, and decided you didn't want to spring for the air hose that was a little bigger and a little more money because the other would work just fine. You could have the same problem. Specially if you thought connecting two 25 footers would get you to the painting area without having to carry the compressor out there.
Here's an example of this the way I was first told years ago, basic science say you have 2 balloons one is full the other isn't and they are both connected by a valve in the middle, lets say you open the valve what's going to happen? You are correct, they are both going to balance out, equal air pressure in both. Let's say the valve connecting both balloons has a very tiny hole, hence your small air lines or hose diameter, the air pressure will balance out but it will take a little longer.
So how does this look in action in the shop or in your garage? You look at your air gauge on the wall or at your spray gun and the pressure looks fine but you pull the trigger and you just can't maintain the pressure the gun manufacturer suggested you use. Here is where pressure and volume are noticed. You'll get your pressure back when you release the trigger because the pressure balances out like in the balloon example but the amount that you need can't flow through your small lines or air hose. Try giving a garden hose to a firefighter putting out a fire and you'll get a hard fast lesson in volume.
The terms to learn here if you're interested are CFM -cubic feet per minute, this is the amount that's moving through your air lines "Volume", and PSI - pounds per square inch, this is the measure of "Pressure".
Please feel free to post any specific questions or problems you might be having in regards to any of these issues and I'll make sure to answer you.
Next time we'll get into a couple of the different types of compressors and how big is big enough. 
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