Troll Hunter Posted March 20, 2018 Share Posted March 20, 2018 I thought I'd post up my attempt at getting reasonable quality air for my novice spray painting programme. I'm approaching the rebuild stage of the total strip down and rebuild of my 110 CSW, and with all the panels removed, and available to be prepped and painted separately, I've turned my attention to trying to get reasonable quality air. As far as I can gather, entrained oil from the compressor and water condensation from the compressed air are the main contaminants that degrade spray painting results, so I have attempted to address both of these problems. I've had a gasoline powered compressor for a few years, and am very pleased with it. I decided that I needed a means to remove water from the compressed air and I needed to be sure that I had an adequate air reservoir. From these basic criteria I came up with the following design. Air from the compressor passes through a 3/8" hose initially to a small entrained oil filter and then through the recycled evaporator unit from my LR A/C system. This is cooled by a 12 volt fan, also from the original A/C system. On the outlet of the cooler is a water KO pot with drain. Air then passes into the accumulator, which is a recycled 100lb propane cylinder rescued from our local dump. This ensures that I always have adequate air pressure even if my instantaneous demand exceeds the compressor capacity. My final air polishing is via a 36" long desiccator filled with desiccant pellets. This feeds my spray gun, via a 1/2" hose, which has an air pressure controller mounted immediately upstream. The photo above shows the air inlet from the compressor and the oil filter. The water KO pot is shown right of centre with a drain valve at the bottom. The water KO pot is more visible above. The photo above shows the reservoir outlet and the desiccator. The top outlet feeds the pressure controller at the spray gun. The final business end, what all the effort is intended to support. I've hung the cooler/fan combo on wiresfrom the neck of the reservoir. This seemed the easiest way to allow me to get the cooler "horizontal" - more or less! This could be important since the air passages go back and forward five times between inlet and outlet, and I don't want to waterlog the system. The desiccator is also hung similarly. For safety, I pressure tested the whole system to ~200psi. I totally filled the system with water, flushing and venting until all the air was out, closed the valves at both ends, I had to install a temporary one on the inlet, and stood the reservoir in the sun for a couple of hours. As the water warmed, only slightly, so the pressure went up. I was chuffed that there wasn't a single leak in all those soldered and compression fittings. So, I had a free reservoir, I already had both the cooler and the fan, and I spent about GBP30 on fittings and copper pipe. If I get reasonable quality air I'll be well pleased! Before I start to use my Heath Robinson contraption, are there any other concerns or improvement suggestions I should incorporate? Mike Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted March 20, 2018 Share Posted March 20, 2018 Neat setup, the only comment I have is on the spray gun end, I'd be inclined to move the regulator away from the gun end. I don't have much experience but I found just having the gun (and a smaller one) on the end of the hose was enough of a hassle to keep the hose out of the way to spray largish panels (88" hard top sides to convert my CSW to a USW) let along with an extra chunk of rigid stuff on the end of it. Looks like a good quality hose so wouldn't imagine you'd have much of a problem with flexibility on that. [edit]Possibly not move it too far away but put it on a pig tail so that it's not such an unwieldy beast[/edit] 1 Quote Link to comment Share on other sites More sharing options...
landroversforever Posted March 20, 2018 Share Posted March 20, 2018 I was thinking pig tail too, that way you've got a nice flexible end for waving the gun about, and you can hold the end/reg/less flexi pipe with your other hand. Quote Link to comment Share on other sites More sharing options...
Arjan Posted March 20, 2018 Share Posted March 20, 2018 Yes - regulator fixed on the tank - hose & gun will weigh enough by the time you're finished. Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 21, 2018 Author Share Posted March 21, 2018 OK, thanks, all, for the comments. I was going by some Youtube vids that show the pressure regulator immediately upstream of the spray gun. I agree, it is heavy. I don't understand the reference to "pigtails", since the pressure regulator must be in the main supply line. Please explain, for the benefit of a geriatric! Mike Quote Link to comment Share on other sites More sharing options...
Ed Poore Posted March 21, 2018 Share Posted March 21, 2018 Just a small piece of pipe so the reg isn't directly attached to the gun. They commonly use the coiled type, hence pig tape. Just adds a bit of flexibility. Quote Link to comment Share on other sites More sharing options...
Scotts90 Posted March 21, 2018 Share Posted March 21, 2018 All my guns have the regulator attached directly to them at the inlet with a swivel hvlp (or euro) male connector from this to the airline which tees from my airfed mask belt/filter. Must admit my set up is as close to pro as I could get in the workshop and I have numerous traps and filters prior to getting near the gun. How much air do you have available? You won't be long in emptying the cylinder when painting a panel, paint guns are air hungry...even hvlp stuff requires a decent supply. Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted March 21, 2018 Author Share Posted March 21, 2018 My compressor manual says that it does 8.5cfm at 90 psig. It cuts out at 120 psig and back in at 90 psig. I'm hoping that the big cylinder I've included will give me the capacity I need. If not, it might just be time for bevvy while I wait for it to recharge. Mike Quote Link to comment Share on other sites More sharing options...
landroversforever Posted March 22, 2018 Share Posted March 22, 2018 I don't know what the air requirements are for a spray gun, but that sounds like a pretty low figure. You may also find the output is actually lower than that as I know over here in the UK most places quote the displacement which is higher than the 'free air delivery', the actual air it delivers. Quote Link to comment Share on other sites More sharing options...
Scotts90 Posted March 22, 2018 Share Posted March 22, 2018 When painting I run 2 x 3hp compressors, one rated at alledgedly 14.3 and the other at 12cfm. The 14.3 has a 200litre tank, the 12 has a 50 and I couple up another 50litre buffer. If painting something decent in size like a roof or baler panels both will run constantly and just keep up supply. My airfed mask needs 6cfm, the devilbiss Gti-pro needs about 12 at 2.4bar but paints beautifully. The primer guns with larger tips are very air hungry, in contrast I have a small smart repair gun with a 0.8mm tip and it is very low on air consumption. Unfortunately waiting on the compressor to catch up isn't really an option if you want to do a decent job. I would dearly love a vane type compressor that chucks out loads of cfm, most are 3phase and cost thousands though Quote Link to comment Share on other sites More sharing options...
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