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electriclightfoot 11-02-2004 07:56 PM

Compressors & plumbing for spraying
Hello everyone

I'm a complete novice & newbie so treat me with care!!

I'll start by praising this fantastic website. I stumbled across it using Google in a desperate attempt to find a solution to my problem. I've learn't loads so far.......this is great, well done to those who set it up and those who contribute by writing in!

My intentions are to learn to spray/bodywork etc. in my home garage. I bought myself a 150 litre (40 gallon), 14 CFM, 10bar (150psi), 3hp oil compressor with a half decent spray gun (1.4mm external mix nozzle) that uses around 7CFM. I've also purchased a regulator/filter that traps water.

click here to see my air compressor

click here to see my spray gun

click here to see my filter/regulator/water trap

From what I understand so far (and it ain't very much and please correct me if I'm wrong), compressors work at high pressure. The by-product of cramming all these molecules is 'super-heating' of the air which in turn causes condensation/water accumulation in the receiver and in the hose line. It makes sense that this isn't a good thing if you want to do a good spray job.

I've tentatively touch on the subject of 'plumbing a compressor for spraying' and it frightens me a little! I know the whole idea is to capture as much water as possible but seeing these densely detailed schematics/diagrams of pipes everywhere is somewhat daunting. They look far to complicated and intended for professional garages. Thats not me! I need something a lot simpler.

Is there anyone who could provide a detailed written setup with some pics (sometimes a picture saves writing a thousand words). It's all well and good stating that this pipe must be vertical and run 25ft from this pipe with a sloping gradient and this pipe does this etc. I also need to know what kind of pipe to use! Is it the normal copper piping available from the plumbing section in your local hardware store? Or is it thicker gauge piping? What thickness etc.? I know some of these questions may sound daft to some of you pro's, but I haven't got a clue!

I've tried to keep things in imperial measurements on here but as I live in the UK under a metric system imposed on us by Brussels, I would appreciate any figures quoted in both imperial and metric for us Europeans. I'm asking a lot I know...but if you don't ask, you don't get!

Any help would be greatly appreciated folks.......even the smallest of input helps loads.

Dean (electriclighfoot)


OneMoreTime 11-02-2004 08:45 PM

Comperssor install
Ok I do not know a meter from a liter but we can try..

1) Pick the spot for the compressor

2)Install an extension on the compressor drain valve so you can reach it easy..

3) Install a swing joint (three street ells together to absorb any vibration and misalignment to the out let of the compressor..

4) Run a line to the ceiling of the shop

5)From there run a line accros the shop to the work station..BTW..put in some drops at convenient spots around the shop for other airtools and such while you are at it..

6) Install a drop from the ceiling line at the workstation..

7) mount the airfilter regulator assy about 4 feet off of the floor at the end of the trick to these filters is to have them out at the end of the line where the air has had a chance to cool and the water condenses and is easier to seperate from the air..

* At the end of each day or shift shut the compressor down and open the drain valve on the compressor tank and the drain valve on te filter regulator and do what we call "blow down your lines" this gets the accumulated water out of the lines and tank..

use "black iron pipe schedule 40" not copper..about 1/2" is fine for a one man shop..

That is what we do in practice when we pipe in one of these things..

Chopper64 11-02-2004 11:20 PM

Try this link. Lot of good info here.

This was posted a few months back. There is a link to an oldsmobile website that has some diagrams on piping.

Good luck, as I am in the same process of plumbing air lines in my garage also.

julmer 11-03-2004 03:10 AM

There have been a couple of different threads on the subject on this forum. Search a little and you should come up with lots of ideas. The only big caution I would add is DO NOT USE PVC (plastic water pipe) for your project.
It looks quick and easy but the pipe will fracture on impact and send shards of sharp plastic all over your shop - and you if you are in there.

electriclightfoot 11-03-2004 06:58 AM

Setup plans
1 Attachment(s)
Thanks very much guys for your input.

I designed a quick diagram - see attached file. Tell me if its ok or where I need to change things etc. and whether there should be a moisture filter/coalescer filter?!? somewhere in the setup?



OneMoreTime 11-03-2004 08:51 AM

Yup your diagram is fine,,,put the filter air /water seperator regulator at your work station..

There you got it:thumbup:

electriclightfoot 11-03-2004 09:17 AM

Compress setup
Brilliant! One more thing, I've never heard/come across "black iron pipe schedule 40" over here in the UK. Is there another name for this piping?

Also you talked about at the end of the day/session, turning off the compressor and "blowing down your lines". How do you do this? Do you literally blow with you mouth? I know it's a daft question but I'm slowly getting there :spank:

thanks Dean

OneMoreTime 11-03-2004 10:26 AM

the schedule 40 pipe is what we use for gas piping..Dunno what it s called in the UK but I am reasonably sure that you guys use natural gas for heating your use that type of pipe..Same stuff..

Blowing down the air ines is done by opening the drain valve of your filter wide open and letting the air escape..and opening the drain on the compressor wide open..the air rushing out takes the excess moisture out...let it run until the air is dry then shut off the compressor..

Really simple deal to do..drains off any accumulated water in the lines and tank..:thumbup: there ya go.

One more thing when you put in the new compressor let it run witht the lines wide open for a break in period...shoudl say something about that in the manual...:D

electriclightfoot 11-03-2004 10:38 AM

The instruction manual does say to run with the lines wide open for a specified period to run her in.

Can't thank you enough.


electriclightfoot 11-08-2004 04:18 AM

Black iron Pipe
Just a little note to folks in the UK who are having trouble finding 'Black iron pipe'. It seems not very popular and hard to locate.

I found a company called PIPELINE based in north London that stock black iron pipe and fittings. Address & phone no. are as follows:

Mowlem Trading Estate
Leeside Road
N17 0QJ

(0208) 808 6633

Click here to view a map and get directions. :D

julmer 11-10-2004 12:53 AM

Black iron pipe is a poor choice for air lines. Its black because it has no coating. It is used for natural gas because gas has a detoriating effect on the zinc used to galvanize pipe which causes the zinc to come loose and end up in the gas stream. Little gas orifices don't like that at all.
The problem with black is that it rusts. Moisture in you air lines will rust the inside of the pipe and then you will be dealing with rust flakes entrained in your airstream. Compressed air and galvanized pipe seem to get along just fine. My personal chioce is copper pipe. It's light, can be assembled with nothing more than a propane torch, is very smooth inside, and helps cool the air off better.
I've had a couple of people say that the total installed cost is only a bit more expensice than other methods and you have a lifetime job.

electriclightfoot 11-10-2004 02:30 AM

Copper pipe
Thanks for the info Julmer. Unfortunately I've just spent a small fortune on Black iron piping and fittings.....if only you mailed a few days ago :pain:

I did wonder to myself if copper piping was up for the job. I thought that soldered joints wouldn't be strong enough to contain compressed air and would eventually leak. I would of rather used copper piping because it cheap and very easy to work with.

I'm now in a dilemma, do I assemble the black iron piping or do I accept a loss and use the 3/4" copper piping I already have in my garage? Hmmmm. :smash: :confused:

OneMoreTime 11-10-2004 07:02 PM

Iron pipe
WEll in over 40 years in the trades always used the black iron for air only lasts about 30 years or so in service so should be ok..Never had any complaint about rust flakes or any of that..

UPC (the plumbing code specified iron pipe) so that is what we used..Only time I have ever experienced any issues was when the filter/seperator was not serviced on a regular basis..

electriclightfoot 11-10-2004 08:14 PM

Iron Pipe
I've been in the garage tonight looking at the iron pipe I purchased. It is coated in orange primer on the outside as standard nowadays due to many plumbers complaining they have to spray it themselves. Upon closer inspection I noticed the inside of the pipe to be painted grey. This grey paint could prevent it from rusting internally. So all is not lost.

I suppose having spent a small fortune on this pipe, I might as well use it. If it does give me trouble later on then I'll strip it out and install copper. In hindsight copper would have been better because its easier to work with. I also wouldn't of had to spend more money on a pipe threading kit. Oh well you live and learn.

Anyone know what kind of oil is used to lubricate when threading a pipe manually? Don't say pipe threading oil :spank: I wonder if I can get away with a little engine oil?

julmer 11-10-2004 10:03 PM

Yes, pipe threading oil! :spank: I've never owned a bottle of the stuff so I use whatever is handy, usually the nearest quart of motor oil.
The only thing I'd say about black iron is be sure and put drip stubs (they should be there regardless of what kind of pipe) below your outlets and filter it right at the wall when you paint.
About copper and pressure. Copper is used extensively for residential water systems where working pressures can range up to 150 psi. That is with generic soldering techniques. There are a couple of different grades of copper and the better stuff is used in air conditioning where it may see 400 psi. The only real difference is the A/C stuff is usually braised or silver soldered. I'm going to be doing my garage soon and I plan on using copper. The only thing unusual is I'm going to use long radius elbows designed for A/C work.
One thing I've seen done is some shops is to run a large (6" or bigger) pipe down the center of the shop and branch off of it for other lines. If it's very long, it eliminates the need for a separate storage tank.

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