CAR RESTORATION HOW TO

How to Install That Air Compressor Right!

We've used several air compressors in the past and learned a lot about the advantages and disadvantages of each. We've also learned how to "plumb" the air compressor to get maximum flexibility out of it. Now that you've bought one, here's what you need to get the most out of your money:

We use a dual-stage compressor with lots of capacity and an upright tank because it takes up the least amount of floor space in the garage. Our compressor is located in the garage because we don't have the ability to put it anywhere else. However, if you have an adjoining shed or lean-to that will keep the compressor out of the weather (important!), consider putting it there to minimize noise and potential ignition of flammable vapors. The tradeoff, in that case, is that you have to go out to control the output valve and to let out condensate* from the tank, an easily-forgotten task.

It's tempting to install a compressor, wire it up and put a quick-disconnect hose fitting on it, then consider the project "done," but now is the time to run lines and other devices to make using the compressor easy and versatile. The first thing you want to do is run a short piece of air line from the compressor outlet valve to an air dryer/separator.

Why do this? Well, because lots of moisture is created in the act of compressing the air and moisture is the enemy of air tools and paint equipment. An inexpensive dryer/separator will save you lots of grief, especially when you sandblast and paint.

Notice that we use a rubber hose from the compressor to the dryer, because compressors create lots of vibration that would cause hard tubing to crack or leak eventually. We installed an air control valve on the dryer unit because it is much more precise in delivery than the main valve on the compressor. A pressure gauge at this valve is mandatory.

A compressor is used for many things, so why not run air lines to the equipment right now, or at least "Tee" the lines from the dryer for eventual installation? We used galvanized pipe to run a separate line over to the blast cabinet, utilizing an in-line shutoff valve for those times we don't want air running there. Rubber hose runs from there to the cabinet. We could have used copper or galvanized pipe, but we had lots of available high-pressure rubber hose on hand.

We wanted to get air to the rest of the garage without stringing hose all over the floor. The solution was to run air up to the center truss and "Tee" it in three places. From the tees we dropped down hose to quick-disconnect fittings, mounted on wood paddles, extending just low enough to reach with our hands but high enough not to bump heads or anything else.

Again, we used high-pressure hose to make the runs because we had plenty on hand. Galvanized pipe or copper pipe (heavy duty only) can be used, of course. We constructed the drop-down connector with a wood plank. The quick-disconnect fitting is held rigidly in place by using a joist hangar bracket, modified by drilling an appropriately-sized hole in the end. Threaded hardware holds everything tightly.

Now we have three easy-to-reach air feeds dropping down across the center of the garage. This allows a one-handed attachment of hose when working on any side of a car without dragging the hose across it, a particularly important consideration when painting. Also, the hoses stay off the floor, keeping them cleaner and safe from damage. Since we can use relatively short hoses we keep pressure losses at a minimum.

*About that condensate, you will notice at the bottom of your air tank a little fluid tap of the same type as found on auto radiators. Notice also that the tap is very hard to reach (you generally have to lay on the floor) and hard to turn with two fingers. Before installing the compressor, take the tap out using an open-end wrench. The tap uses 1/4 inch NPT fittings, so go to the hardware store and get some galvanized 1/4 inch fittings: a 90-degree elbow, a few nipples and a coupling (or two) will do just fine. Use Teflon tape or plumbing compound and construct an extension piping to bring the tap out to the front of the tank where it can be easily reached. Keep a tomato can or plastic tray under it also. You won't believe how much water comes out after a lengthy period of sandblasting.