Air compressor advice: 1/2 or 3/4 lines?

Hello all. I am getting ready to start my tail kit, and I am setting up my air delivery system.

I have an 80 gallon compressor in my utility room, and I want to run airlines to my work room, which will be my unfinished basement, while I build the tail and wings. Then I will move the "factory" out to the garage.

So, I will be running airlines to both rooms. My compressor has a 3/4 outlet that I can take advantage of, and I want to install a good filter/dryer/regulator and I have found some in both 3/4 and 1/2 sizes.

Should I worry about the little extra costs and hassle (not as easy to run) of doing 3/4 airlines to feed a few drops in the garage and basement? Or should I just save some money and time and do it all in 1/2 in?

Is there any significant difference for riveting and primering by using the 3/4 main lines?

Do not consider 1/2" lines. Too much pressure drop when you start using high flow tools. 3/4" minimum for the header but 1" would even be better and you can drop down to 3/4" for the drops. This is especially true if you ever connect an impact wrench to it.

3/4

3/4 and keep the runs short if possible. You will probably use die grinders as well as that impact gun and they like to suck up air relentlessly.

You'll never be sorry.

Jerry

I used 3/4" copper for my shop. I like how it turned out but if I had to do it over again, I would have just done RapidAir. It took me several weeks to plan, cut solder, etc. It was also pretty pricey for all that copper.

I am glad that I went ahead and plumbed the shop vs dragging an air-hose around.

Wow, I guess my 1/2" RapidAir setup isn't really working for me at all. Wish I'd known that before I did all that drilling, riveting and painting.

If I were doing it again I'd probably run 1/2 or 3/4 copper... but that's really just because I have some slow leaks. I have absolutely no problem using the squeezer, rivet gun, air drills or spray gun. Of course my runs are probably shorter than yours will be since I have the compressor in the garage where I'm working.

I am looking at a RapidAir system, or even possibly using PEX. I have heard of some folks running plain old PEX and it serving them well. Another benefit is that if it does fail, it usually just splits instead of exploding into shards like PVC.

I have also been looking at Maxline, which is on Amazon: http://amzn.to/1KizN58 and its very similar to RapidAir.

The installation in the basement will be sem-temporary, as once the airplane is moved off to a hangar for completion, the basement will be finished out for another room.

Size

Here's a few pictures of my set up. I measured 5/8 OD and 1/8" wall copper. Google some pictures of exploding PVC I would definitely stay away from that for high-pressure air lines. I'm running a 60 gallon compressor at 175 PSI. After the first dryer regulator I drop the pressure down to 150. No problem running any air tool whatsoever including impact wrenches. This setup probably wouldn't work if you had multiple users running high demand tools at the same time. The cost of putting copper in is not cheap though several other options out there May be cheaper. The other thing I would invest in is a quick tank drain valve. Keeps from having to clean the water traps out constantly of course I live in South Texas though. Good luck on the build.

CubedRoot said:

I have heard of some folks running plain old PEX and it serving them well.

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I have my compressor in a different, but attached garage from my shop. Run the air thru about 80 feet of 3/4" PEX. I'd probably go with 1" if I did it again, but the pex has held up awesome since installation 3 years ago. Used the cheap copper crimp rings, and didn't expose any coming down from the ceilings. Used copper-pex fittings then ran copper down the walls.

I used 3/4" galvanized sch40 pipe. I found it to be the least expensive and built like a tank.

i used 2" schedule 40 and never missed a beat. 3/4 i always had to wait.

My neighbor used PVC. I like his set up quite a bit.

My concern with using PVC is that the stuff explodes into tons of high speed shards when it ruptures.

I do like PEX, since it just splits with no shrapnel. Its also a lot more cost effective than doing copper, or RapidAir.

I did quite a bit of research before installing my system. The one common denominator was "Do not use PVC." You might be fine for years but it gets brittle as it ages. And when it goes, it explodes with shards (high speed projectiles) going everywhere...

I installed my home system 25 yrs ago and used 1/2" black pipe. It was a pain as each threaded joint had to be rethreaded to prevent leaks. Maybe, 180 joints later, it does NOT leak. I used aviation permatex Aviation #3 on the joints. I leave the system pressurized all the time, and with the compressor in the basement, it won't run if not used in more than a month. Leaks are expensive.

Actual 1/2" pipe is like a real 3/4" ID -since the 1/2" is hydraulic diameter.

My 60 gal is 2 stage compressor and 175 psi. I step the pressure down at the wall exits (8) if needed . TPTools has a good write up on how to assemble a system. A little too extreme maybe, but it will eliminate issues, many of which I have had.

With some research, you will find that copper is best, but be sure to use a solder adequate for the job. Plain-ole is not good enough.

The PEX like system is good to 125 psi IIRC, so you might have to have a whole system regulator installed - expensive for full flow. The pressure is be the drawback, but may be worth the time saving.

Black/galv pipe? Very long lasting, but care should be taken to pressure test often during installation. After years it WILL blow iron chunks. It depends on how long you want to keep the system in place. Copper is better but more costly.

Yes, PVC can be used, but I am sure that once in a while one can skydive without a parachute and live too.

Be sure to use some flexible connection from the tank to the system to reduce rattle and fatigue.

Pressure drop is the last thing you should be concerned with.

Good Luck, this is like primer wars.

Edit: Try this link to calculate CFM - I just found I have 224 CFM capability - like I said - last thing to worry about.

Gee! Ive had 3/4" PVC for years and I've survived fine! Not a single incident! If your worried about it exploding, put some insulation around it or duct tape. Spend all that extra money and time on building an airplane! Coarse I've always been the "reckless type".

Wow. I ran multiple 1/4inch flexible lines from my air compressor and never felt I needed any more. Sure glad I never visited any of your Taj M'shops....or I would have known what I was missing.

This is why I went with copper and a high quality compressor...





Not meant to scare, but food for thought..

PVC weakens significantly with temperature. Note that 80% strength reduction at 140F. If it is installed in an attic or walls, then there is a risk of repairs. Each selects risk that is acceptable. It's a free country, so far - so good.

Any schedule 80 PVC experiences?

Any thoughts or experiences with schedule 80 PVC? Schedule 40 is definitely not the right choice, but I'm curious about the much more robust schedule 80 PVC?

Thanks in advance.

Fly2KiteSurf said:

Any thoughts or experiences with schedule 80 PVC? Schedule 40 is definitely not the right choice, but I'm curious about the much more robust schedule 80 PVC?

Thanks in advance.

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Well, there is much more margin with SCH 80, but . . . One factor is when using the compressor for high volumes. The tank heats and exit air is warm. Metal lines, Al, Cu, Fe, all cool the air and help with condensation. It is not a good situation, as it means the compressor is too small, but typically we work stuff as hard as it will work - guys, cheap, right? So, if the plastic does not cool the air then it will cool when expanded . . . in the tool, and that is where condensation will occur. Sand, bead, blasting, for me, is typically the greatest demand and the extra cooling is needed.

Good thought on the SCH 80, though. Just plan your system with all the facts you have. Originally, I wanted a robust system that would last for years. Black pipe filled that bill nicely. Now that it is aging, the rust flakes stick in the quick connect check valves periodically and I have to replace them.

Use what fulfills your need within your budget, but be aware of the limitations. Take a piece of PVC and heat it with a hair dryer, it will get soft and bend pretty quickly. Satisfy yourself as to the usability of PVC for your situation. If I was going to make a long run underground, yes SCH 80 would work, but not in walls, attic, or near the compressor tank. Drop the pressure to 100 psi, even better.

I used PEX-AL-PEX 3/4

Short answer, I used 3/4 and it was no more difficult than 1/2.

I placed my compressor in the basement with easy access to 240VAC and not near any livable place. I wanted to isolate the sound. I decided to use the purpose built Rapid AIR system, specifically the 3/4 flexible lines. The line is actually similar, if not identical, to the dimensions and materials of PEX-AL-PEX pipe for heating applications. I was able to snake an 80 foot run from the basement up one floor and over to my shop. It has about 4 90degree bends in it and I was able to avoid having any connections in the run. I love the tube.

I needed more to make my multiple drops and I decided to try using commonly available PEX-AL-PEX tubing 3/4 from an eBay supplier that supplied it with free shipping in 100 and 300 foot coils. Unlike traditional PEX tubing, the PEX-AL-PEX has a layer of Aluminum in it that allows the tube to keep its shape when bent and also allows it to be straightened. The non PEX-AL-PEX tubing that comes in coils or sticks does not bend easily nor retain the shape once released.

I also ordered common PEX-AL-PEX compression fittings from this same eBay vendor. Everything is working just fine and the eBay parts were much less expensive than the purpose built parts.

As a side note, I asked Rapid Air what size to use based on my need and they recommended 3/4.

On another note: I did not want my compressor to always have power applied to it so I ran the 240VAC from the circuit breaker panel to a small NEMA box and installed a contactor. I wired the 240VAC to the contactor (In/Out). The contactor "makes" the circuit when 24VAC is applied to the switching coil. I ran thermostat wire up to the shop and terminated it into a normal household switch placed on the wall near the door to the shop. When I go out to work on the plane, I flip the switch, which applies power to the contactor coil and energizes the Compressor line. When I quit for the day, I turn it off, making sure the compressor does not cycle on when I am gone or if I develop a leak when I am not home. This is how the central AC compressor works in your home.

I like the set-up. I have enough air for riveting, painting, drilling. I have not used my angle grinder much, but I saw no issues when I did. Best of all, no noise in the shop.

um....can I say ya all are a bit overkill here. Go look inside your 1/2" impac gun or die grinder air fitting, ID is smaller than 1/4" I am running 3/8" OD DOT air brake hose with quick slide connectors, built and painted my 7a this way.

I do not have any hard lines. I hook the flex line directly to the compressor. I have always used 3/8 inch without a problem except for one tool. It is a 1 inch impact wrench that I use to change tractor trailer wheels and stuck -3s. I have to use a 1/2 inch line to get full power.