This project just sort of snowballed. I'm in the process of repainting my Tundra. Before I even started, I knew I had to do something to upgrade my shop compressed air system. I originally had a Kobalt 1.8 HP/30 gallon compressor and a single inline water/oil separator. It is adequate for painting cabinet doors and other small projects. However, during very hot and humid months down here in NW Florida, I'd sometimes have water coming out of the spray gun or other air tools.
I started searching craigslist for larger compressor, one that could supply adequate air to a spray gun my itself. I found one that I thought was a 6.5HP/60 gallon. It was labeled as such. I paid $350 for it. When I got it home, I realized it had a new Harbor Freight 3 HP compressor and motor. Good that they're new. Bad that it is still inadequate.
So, I needed to address the moisture in the system and somehow connect both compressors together so I'd have 4.8 HP and 90 gallons. The recommended minimum HP for autobody work is 5 HP. I'm close.
Here's the schematic for the completed system. I took the output of each compressor directly to an a/c condenser via a teflon braided hose. The air coming out of the compressor head is very hot, and I was worried about melting a rubber hose. I bought the brand new, universal a/c condensers off eBay for $40 each. I picked up the braided hose at a local rubber specialties shop, and the fittings off the O'Reilly auto parts website. I believe they are a No. 6 and No. 8 fitting, but the size is condenser specific. I suggest that you have the hose people make up the braided hoses. It was a **** getting the fittings into the braided hose. I had to sand off most of the barb from the brass hose barbs because the 3/8" teflon braided hose isn't really that. It is smaller. This was the hardest part of the whole project. Just let them do it.
From the a/c condenser, the cooled air goes into another tank that acts as a water trap. The temperature drop is 100-120 degrees F. I can see water streaming down the clear hose into the water trap. The water stays in the tank, and the dry air goes back into the main tank.
I had to add an inline check valve between the condenser and water trap, and a tee fitting upstream that connects to the unloader valve. With the unloader valve connect to the in-tank check valve, the entire system had to leak down, which took forever. I was worried the compressor would try to kick-in before the compressor head unloaded adequately.
I built a fan enclosure for the condensers and mounted them inside my workshop. During the summer months, I air condition my workshop, so the cooler air will make the condensers more efficient.
The output of each compressor goes into a sloped iron pipe that goes through the wall into my workshop, then through a pre-water/oil separator and then into the QC-3 desiccant. filter then a regulator.
Ultimate Compressed Air Dryer
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We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
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The last step is to adjust your pressure switches for cut-in and cut-out pressures, and differential setting if you pressure switch has that adjustment.
Here is a good video that explains how to adjust them. https://www.youtube.com/watch?v=zh_hfD3rCA0 For my Kobalt 1.8 HP, my pressure switch is preset at the factory for a 30 psi differential between cut-in and cut-out. It cuts in at 125 and cuts out at 155. That was too high for me. I think my welds on the water trap tank are good. Had that nice sizzle going while I made C-shaped loops molten metal around the circumference of the steel nipple, but I'd rather not do a test-to-failure on it. I had to by a tamper proof torx set, but I was able to back it down to 106/126. The differential is fine I think, but I can decrease the differential if needed. In other words, I could use the differential adjustment screw to make it cut-in at 116 and cut-out at 126, instead of 106. The Square D switch on my big compressor only had an adjustment for cut-in/cut-out. Differential is preset and not adjustable. They both kick in and out at about the same time. I set the large one to kick in first, then the smaller one a few moments later. This was a little confusing at first, but now I fully understand it. I did a test by hooking up my primer gun and wired the trigger open. I let it spray wide open for a very long time, much longer than it would take me to go around my truck. Both compressors cut in, but the pressure remained steady at 100 psi for the entire time. Also, the air coming out was completely dry. We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
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Understatement of the year...
"This project just sort of snowballed" My setup: 60 gallon comp, drain tank before spraying, 100' air hose, and a new one of these for finish coats |
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I don't think my 3HP/60 gallon compressor would hack it, so the tandem set up was inevitable. The dryer part? I was on a mission! We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
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