Technical PLumbing the shop for air-paint quality air

OK guys, some of you may have seen the fisheye in my paint thread way back in the summer.

https://www.jalopyjournal.com/forum/threads/trash-in-paint-getting-ready-to-slit-my-wrists.1140940/

The culprit finally reared it's ugly head. My compressor is dying. I found oil puddled in my coalescent filter setup.

I am saving my pennies for a new industrial compressor. Should last me the rest of my life. The new compressor is a 7.5HP 80 gallon with a after cooler. Here's my question.

Should I replumb the shop so that I don't transfer the contamination from the previous compressor?

I thought about removing the filters and putting in a stick of tubing temporarily to purge and wash the lines. It's all galvanized 1/2" pipe, so water won't hurt it. I thought maybe use some Dawn dishwashing detergent and a water hose to flush the lines.

I hate to replumb the entire shop over this. I have even pondered a dedicated line for the paint booth. Use the other line for sanders and tools. Cross contamination scares me.

I have a coalescent filter at the gun as well.

I don't think the problem will ever go away until I get the compressor replaced.

 

I’d run new hose all the way from the booth to the new compressor with a quick disconnect right at the compressor. Removing the hose and storing it when not in use. Keeping both the tool compressed air system and paint system separate.
I also very slightly opened the drain on my new compressor leaving it open just enough to empty the moisture every time it’s used. I leave this drain opened all the time. Stays dry that way without the worry of trapped moisture and periodic draining. I always turn my compressor off when not in use.

 

The new compressor has an automatic drain on it. Hopefully between the after cooler, a drier and the automatic drain, the problem should go away.

 

After spending over a week installing all my air supply piping (1/2" black iron), there is no way I'd remove it if it got oily. I would definitely try to clean it. My system runs downhill from the compressor all the way to the other end of the shop, and I have condensation cleanout drops in a few spots. I'd try the Dawn like you said, or maybe some Simple Green. Then fill with clean hot water a couple times, then let air blow through for a long time. And filters at the gun always.

 

The new shop we're building will have copper air lines to minimize contamination. Galvanized (eventually) and black iron will break down internally and give you contaminated air. Whether the hassle of replacing all is worth it to you I can't say, but going copper is a long term thing and how long is "long" is up to you.

 

Think i would replumb it using pex tubing. It has a lot of advantages over black pipe. Easy to thread through, less condensation, no rust, weighs less, and can use Shark Bite fittings. Not sure of the cost in your area.

 

I used copper lines in my shop,just the regular 1/2 copper tubing you buy at the hardware store,is real easy to use,there are a ton of different ends and bends to use,not that expensive either.compressor shuts of at 165 psi,never had a line bust yet,has been in for 18 years.I would definetly do it again if i had to.Harvey

 

I'd probably save all the effort and switch to a good HVLP turbine system like this Fuji 5 stage model.

https://www.paintsprayersplus.com/F...-G-XPC-HVLP-Turbine-Sprayer-p/fjgxpc-2895.htm

I used a 5 stage turbine system and Fuji gun to paint my RPU.
I really liked it.
I also used the 3M PPS paint system with it.

 

I would just run a new dedicated line to the booth. No need to start all over for air tool use in the shop.

 

I have a dedicated airline for the paint gun only to avoid contamination
Alcohol flushed through your airlines will clean and dry them- be careful though- it is very flammable

 

I wonder if a gate valve would prevent cross contamination? I guess that is more of my question. I plan on buying a seperate drier/filter for the paint line.

 

No comments on the kits using aluminum tubing?I've been considering that set up for my shop.Pros and cons on this method?Will be exposed to hot and cold temp extremes

 

I talked with the guy I am purchasing the air compressor from about this. He said the downfall of those type of systems is the orings. He said eventually, the life of the orings will peter out and he said depending on the amount of junctions you have, it could become a very laborious task keeping up with the leaks.

I have probably 150' of piping in the shop. I think a dedicated line for the paint booth, with a ball valve, is in store for me.

 

The 1/2" black pipe air lines in my garage are 44 years old , I have had 2 compressor failures , I use an ancient Binks regulator/ oil seperator/ water filter and throwaway dessicant filters at the gun , I've never had a contamination problem in all that time . A CH combo reg/filter/dessicant setup is less than $100 , the gun mount filters used to be about $6 ...I know one body shop locally that the piping is at least. 55 yrs old , I helped the owner put it in ..spend your money as you see fit ..

 

I have 1/2” galvanized pipe, basically the same thing as black pipe. I have a ton of filtration and still have issues. Somethings gotta give, paint ain’t cheap.

 

I know I'll hear people say this is wrong....

I would consider using the white PVC piping for your spray gun line. Tap off your high pressure line and run a larger
3/4" to 1" LOW PRESSURE line where you want only spray gun access. I'd run the pipe kinda high with a couple drop downs. This gives you lots of volume availability with low pressure. I've seen the videos of plastic pipes exploding .....when they appear to be hit suddenly with air that is already at high pressure. I have been using PVC pipe for 30 years and never had a problem, and I have 4 80 gallon 175 psi compressors hooked up with it. Yes, I can't swear no one will ever rupture a pipe, so everyone has to make their choices. Three of mine operate fine with the high pressure. The 4th one is in a home built paint booth and its limited to about 50 psi but plenty of volume and cooling.
If you only plan to operate a high volume/low pressure gun, its quick,cheap and efficient.

As for your other line, if you decide to continue to use it, I would fill it with kerosene and let it set for a few days.
Then I would apply LOW pressure and drain it in a white plastic bucket. Refill the pipe and let it set a few more days and repeat. When the kerosene looks as good coming out as it did going in, I'd leave the system open and blow air thru it for 10 minutes or so. Then leave it open for a few days. Then get some old left over paint and spray it.
Check for fisheyes.

Note: In the pictures below I used a combination of copper, cast iron and rubber because I made a large water separator from copper pipe. This compressor is under roof but is "outside " for all intents and purposes. I felt the copper would work better for transferring heat and riding the air of moisture. After the air enters the shop, there is an old water separator housing that I modified and packed with filter material to catch any debris that my large cooling system might contain. Then the air goes to a second 3/4" oil/water separator /pressure regulator. As it exits the pressure regulator which is permanently set at a low pressure, it enters PVC pipe. You should also use the large "industrial" hose fittings rather than the small "orifice" automotive fittings. The thread size is the same but the orifice flows double/tripple the air.....which is great for your HV/LP spray gun. I read somewhere thats its best to adjust air pressure at the pressure regulator on the pipe and leave the one at the gun wide open. Can't say that works for everyone but its nice to have the option.

 

I plumbed mine with copper. Never a problem. I would definitely put a good filter at the end.

 

just a shot in the dark but your contamination issues could be coming from other sources , sandpaper , rags , anything from the heating supply , something other than the air supply , also , are you using a fish eye eliminator ,? Never liked that stuff ..

 

Wish I had pictures of my younger Bros " plastic will work fine" injuries , that stuff decays with exposure to light . And you guys using copper , make sure it's type "M" or refrigeration tubing...

 

2old , what happened to the plastic and your brother ?

 

When the pipe split it was like bamboo ,shards ,if you will , penetrated his right arm , stomach and right thigh , very painful plus infection issues ...not fun .. 3 year old pipe , 150# pressure.

 

That sucks , the reason I asked is because I used schedule 40 -3/4" and I always thought about something like that happening .

 

Not wanting to derail Roothawg's post but PVC is not rated for air pressure and it does not rupture like a metal line it explodes when it fails sending razor sharp shrapnel flying across the room like a bomb. As 2OLD2FAST mentioned it decays from UV but also heat cycling and oil.

 

I wonder if you ran the air through the line and let it siphon mineral spirits through it, would it flush better?

 

If your system worked before your compressor went bad I would think it will be ok with the new compressor and a new filter. I would also get a new rubber hose for at least the paint shop. The hose is usually your lowest point and holds all the crap.

 

mgtstumpy. When I was selling tools, decades ago, I provided that diagram to anyone who wanted it. It doesn't get any simpler than that, and very effective. Never heard of anybody having a problem if done that way.

 

Was he using schedule 40 or schedule 80 pipe ? Did he pump up the compressor and release it into the pipe or was it a gradual buildup ? Pressure ratings for the 80 pipe are quite a bit higher than home compressors can pump. There is also a pvc pipe thats thinner than 40. Which did he use ?
The thing that always concerned me with black/galvanized pipe is that it rusts inside over time, and that can't be good for paint. I don't see doing a low pressure section of pipe out of Schedule 80 pvc as being a problem. They put pressurized water in them with no problems. I think the sch 80 has like 400/600 psi rating. Heat can affect it if you have it taking the hot air right at the compressor.

 

No, I don’t use the fisheye eliminator. I think what I may do is tuna brand new air hose into the paint booth after I get the new compressor installed, no piping. Then spray some pieces to see if the issue remains. If so, we know we have another problem. I use grease and oil remover, final prep wipe and I use the same brand material from start to finish. I have a 3 stage drier/filter, and I have 3 drops with an extra water trap/filter about 1/2 way through the system.

I also run this on the gun now....just added.

 

This air cleaner was sprayed last weekend. Don’t know if you can see it or not.