Paint guns

Siphon gun - The paint in the cup is beneath the nozzle. A suction lift is required to get the paint to flow uphill and out the nozzle tip.

Gravity gun - The paint in the cup is above the nozzle. Paint flows to the nozzle tip by gravity.

Pressure gun - The paint in the cup (could even be remote from the gun) is forced to the nozzle tip by air pressure in the cup.

You need to compare your gun's air consumption demand with your compressor's ability to supply it in cfm (cubic feet per minute). A 15 gal tank storage is quite small and generally indicates a low cfm compressor. However, it's the cfm capacity of the compressor that really counts. Without knowing the capacity of your compressor, and going only by typical tank sizes, my guess is that you do not have enough air flow to support a full sized spray gun except for only short periods. They typically require 8-15 cfm. On the other hand, your compressor may a have better time supplying a smaller "touch-up" gun, sometimes called a "spot" gun. They generally run on the order of 2-5 cfm. They have a smaller pattern size (e.g. 3"- 4" instead of 8"- 9") and hold less paint in the cup.

The guns that dominate the market today are gravity feed, hvlp guns. Hvlp stands for "high volume low pressure" and was developed in order to minimize overspray and comply with environmental air-emission regulations in many areas. Unless you are in an area that requires their use by law, or are using a lot of expensive paints, you do not "need" an hvlp gun. The older non-hvlp style guns do the job well.

You can paint an entire tractor with a spot gun, provided you do it piece-by-piece. You should break it down or mask it off such that the area to be painted each time does not require more than about 4 oz (typical cup size for a spot gun) per coat of paint. You can see my spot gun (4.8 cfm) in use painting a fender for my AC-B here.

Rod

What type face mask are you using in that pic of the fender job?. I have a fresh air system but dont like the hood/mask combo that came with it, kind of chinsey.

scott#2

That mask of mine is about 25 years old. It's a continuous flow, full face, supplied-air mask intended to be supplied with air from a compressor, not a turbine like the Hobby-Air units. It is made by Pulmosan Safety Equipment Co. which seems to be out of business, or absorbed by somebody else. Currently, both SAS and Survivair (and probably others) have similar masks, available both individually and complete with small, tankless, oil-free breathing air compressors to provide the air.

I use an old 1hp portable Campbell-Hausfeld compressor (also oil-free and tankless, but noisy) to supply the mask through 50 ft of standard 3/8" ID air hose. It operates at about 3.5-4 cfm at about 8-10 psig while supplying the mask. That's about the minimum supply capacity needed for a mask. A hood requires a little more, something like 6 cfm as I remember. I always verify there is adequate capacity to maintain a positive pressure inside the mask by inhaling, while at the same time checking with my hand for a continued positive outflow of air at the exhaust port. The outflow of air will always decrease during the inhale, but if it actually stops, positive pressure is lost momentarily, which is an indication the air supply rate is inadequate.

My system has no formal agency "approvals" except possibly for the mask itself (if so, it's probably not current). It works fine for my purposes. It's not for someone who needs to wear regular glasses while painting. If that's the case, the full hood is probably the better choice.

scott#2