Plumbing in air

[Licensed to kill]

I know this subject has been discussed at length but I haven't found were this particular "angle" has been so....I wanted to plumb the air around my shop with 3/4" copper until I priced it out. Then was going to go with 3/4" black pipe but then, talking with a friend and he tells me he has 1/2" SS and all the fittings I would need free for the taking. I suggested that perhaps 1/2" would be too restrictive and he suggested that, rather than plumbing it in a horse shoe across the back wall and up the sides that I should make full loop all the way around the shop. That way, when drawing air from any place in the loop it would be fed from both directions and effectively double the volume that I would get from a U shaped circuit where the air only comes from one direction. Thoughts?

 

[PontiacFan]

www.transair-usa.com
There's a calculator there that you can download & use to determine true efficient pipe size.
(That's a Powdercoated aluminum tubing, with press-fit fittings.)
I know ya don't need to buy, but I use it all over out here in the Nebraska teritory for implement dealer shops, acerage farm shops, industrial plants, etc., etc.
I really like working with it. Sure a hell of a lot faster & easire than black pipe or copper tubing.

Yes, full loop is always better, because as you mentioned, you'd have half the pressure drop.
What size hp/scfm compressor are you working with?
What size building?

If it's 15hp/45scfm or smaller, my guess is yes, 1/2" is large enough.
But respond with those answer I'll give the losses calculated.

 

[pcmeiners]

Just because you use two pipes (1/2") does not double the volume over a single pipe equivalent (1"), never does even if the pipes were parallel to each other to the output. Copper sweat has less friction loses then pipe and threaded fittings, but two 1/2" runs of the stainless would be very close to one run of 3/4" copper. Pro for stainless.. rust resistant, radiates heat better then copper, sections will not separate in a fire situation.

http://www.freecalc.com/gasfram.htm

 

[78Bird]

SS would be fine... Though I doubt it radiates heat better than Cu. There's a reason heatsinks (good ones) are solid copper not SS.

Copper moves heat the best of any non exotic material I know of.

 

[Frank The Plumber]

You're going to have to calculate pressure, volume and equipment use. There are a ton of systems out there for air. You can use copper, steel or a sch 80 pvc, and these will work well. Lesser materials = lesser reliability, you be the judge.

 

[Frank The Plumber]

Just because you use two pipes (1/2") does not double the volume over a single pipe equivalent (1"), never does even if the pipes were parallel to each other to the output. Copper sweat has less friction loses then pipe and threaded fittings, but two 1/2" runs of the stainless would be very close to one run of 3/4" copper. Pro for stainless.. rust resistant, radiates heat better then copper, sections will not separate in a fire situation.

http://www.freecalc.com/gasfram.htm

Nice sizing chart.

 

[Stuart in MN]

You're going to have to calculate pressure, volume and equipment use. There are a ton of systems out there for air. You can use copper, steel or a sch 80 pvc, and these will work well. Lesser materials = lesser reliability, you be the judge.

Except for the PVC...there's about a million discussions here explaining why it's not designed for use with compressed gases.

 

[Frank The Plumber]

Except for the PVC...there's about a million discussions here explaining why it's not designed for use with compressed gases.

Sch 80 can be used with ambient air, granted it's not the best stuff to use. It has a tendency to build an electrical charge from the air flow so it has to be grounded. There is a company selling a kit in some form of poly on the car shows on spike tv. The white sch 40 is a no. I did mine in 3/4 L copper. Maybe we'll call it sch 80 CPVC. The gray **** with the green or blue glue.

 

[j-guenth]

how big of a garage?

By running a loop you should have the required air at each fitting.

For those 1" air impacts you should use larger size pipe.

You can always split off a 1" or 3/4" line for those larger "CFM" tools.

 

[Charles (in GA)]

What are you waiting for? Get it while you can. It will work nicely unless you are running Something really outlandish and huge that your compressor probably cannot handle anyhow.

Charles

 

[pcmeiners]

"Copper moves heat the best of any non exotic material I know of."
Aside from silver this is correct as to heat conduction, but copper is a rather poor radiator of heat, conduction and and radiation (of heat) are different charateristics.

 

[Charles (in GA)]

You can use copper, steel or a sch 80 pvc, and these will work well.

Not if you are OSHA regulated. Sch 80, Sch 40, doesn't matter, its PVC and if it bursts, its dangerous, plain and simple, doesn't matter what the pressure rating on the pipe is.

Charles

 

[Frank The Plumber]

If you have free stainless and fittings just get it done.

 

[Frank The Plumber]

Not if you are OSHA regulated. Sch 80, Sch 40, doesn't matter, its PVC and if it bursts, its dangerous, plain and simple, doesn't matter what the pressure rating on the pipe is.

Charles

How would you be OSHA regulated in your home garage? If you can burst Sch 80 CPVC you could burst "M" or "L" copper. What the heck kind of home shop compressor are you running that you're gonna burst sch 80 CPVC?

 

[padstack]

Just because you use two pipes (1/2") does not double the volume over a single pipe equivalent (1"), never does even if the pipes were parallel to each other to the output. Copper sweat has less friction loses then pipe and threaded fittings, but two 1/2" runs of the stainless would be very close to one run of 3/4" copper. Pro for stainless.. rust resistant, radiates heat better then copper, sections will not separate in a fire situation.

http://www.freecalc.com/gasfram.htm

Good call. If nothing else, just calculating the area of the diameter will give you a rough estimate - Area = Pi*r^2

Area of diameter of 1/2" pipe = 0.196"^2
Area of diameter of 1" pipe = 0.785"^2
(both approximate Pi @ 3.14)

almost 4:1 difference! I'm sure that isn't perfect and doesn't tell the whole story, but it should give a quick rule of thumb comparison.

 

[BLUBAYOU]

How would you be OSHA regulated in your home garage? If you can burst Sch 80 CPVC you could burst "M" or "L" copper. What the heck kind of home shop compressor are you running that you're gonna burst sch 80 CPVC?

it's not the burst strength that's the issue, it's the way it fails (split in copper vs. PVC shrapnel) from what I understand

 

[Charles (in GA)]

How would you be OSHA regulated in your home garage? If you can burst Sch 80 CPVC you could burst "M" or "L" copper. What the heck kind of home shop compressor are you running that you're gonna burst sch 80 CPVC?

it's not the burst strength that's the issue, it's the way it fails (split in copper vs. PVC shrapnel) from what I understand

I didn't suggest that you would be OSHA regulated in your private garage, I just stated that IF you have a shop that WAS regulated by OSHA, you could not use PVC. The implication is, of course that OSHA is on to something here..... The dangers of PVC shattering and creating sharp shreds of plastic that can injure anyone in the area. Metal pipe does not shatter and scatter bits and pieces all over the place, it merely splits. ABS based plastic pipes, that are OSHA approved by the way, also simply split, and do not "shatter and scatter". PVC is great with liquids, as they have no continuing force behind them once the initial pressure is relived, as you cannot compress a liquid (at least none to speak of) and gasses such as air are quite compressible and represent a large amount of stored energy.

This has been hashed and rehashed for years on this board and other boards on the 'net. We've had testimony form GJ members who have been personally involved in PVC/compressed air explosions and the destructive force and dangers of it.............

Charles

 

[Torque1st]

OMG, another PVC is safe for air advocate...

 

[glntom]

I was in a shop(NOT MINE) last week when the pvc overhead air line let go. It blew a 10 inch diameter hole in the adjacent insulation and showered us all with debris. Pieces of the pipe ended up 20-30 feet away. Luckily we were under a rafter and the pipe let go just above the rafter shielding us. IT DOES HAPPEN.

 

[Frank The Plumber]

OMG, another PVC is safe for air advocate...

Not at all, it just seems so few do it in pipe that I didn't want get the guff from the pvc love crowd either.

 

[Underdog]

Go for it. SS will last a lifetime I bet. Only downside might be threading it, use the right lubricant (whatever that is?) and sharp dies.

 

[AMCguy]

Instead of thinking what's the minimum pipe size that will supply the air without a pressure drop, (if you can't afford an air dryer) consider a pipe size that will slow down the flow of air enough to allow more time for the pipe to absorb heat.

 

[Nighttrain]

I didn't suggest that you would be OSHA regulated in your private garage, I just stated that IF you have a shop that WAS regulated by OSHA, you could not use PVC. The implication is, of course that OSHA is on to something here..... The dangers of PVC shattering and creating sharp shreds of plastic that can injure anyone in the area. Metal pipe does not shatter and scatter bits and pieces all over the place, it merely splits. ABS based plastic pipes, that are OSHA approved by the way, also simply split, and do not "shatter and scatter". PVC is great with liquids, as they have no continuing force behind them once the initial pressure is relived, as you cannot compress a liquid (at least none to speak of) and gasses such as air are quite compressible and represent a large amount of stored energy.

This has been hashed and rehashed for years on this board and other boards on the 'net. We've had testimony form GJ members who have been personally involved in PVC/compressed air explosions and the destructive force and dangers of it.............

Charles

PVC is great with liquids, as they have no continuing force behind them once the initial pressure is relived, as you cannot compress a liquid (at least none to speak of)

My wife would beg the difference. Almost put her eye out once with compressed liquid.

 

[Licensed to kill]

Thanks for all the thoughts. Some more info. The compressor is a 5HP/20CFM@150psi IIRC, the shop is 40X60, at present the most air power in the shop is a 3/4"/1200ft/lb impact and I need all the grunt it can supply. Most fittings will be swedglok compression fittings but a couple will be pipe thread and yes, I do have a 110V drier.

 

[sberry]

While 2 of the 1/2 do not deliver what a one inch does they do double what one does. If they are in a loop will run a 3/4 gun fine, for short runs 50 ft or so 1/2 will run a gun fine. The rest of your tools will likely run with 3/8 air hose anyway so the point is moot. You cant get better than the stainless. If there was a case it wouldn't meet demand which I am sure would be rare run larger hose back to comp. My shop uses 3/8 on reels but I have a couple pcs of 1/2 just for heavy impact and sandblast, hook ahead of the reels.

 

[PontiacFan]

Thanks for all the thoughts. Some more info. The compressor is a 5HP/20CFM@150psi IIRC, the shop is 40X60, at present the most air power in the shop is a 3/4"/1200ft/lb impact and I need all the grunt it can supply. Most fittings will be swedglok compression fittings but a couple will be pipe thread and yes, I do have a 110V drier.

Using the line size calculator, you'd only be at 1.07psid loss for that full loop system. (2.13 for a single line run.)
We like to stay under 5psid. Some people say 5% is still efficient enough.

1/2" is purely capable of handling that scfm/psi load.
Use your free stuff & get it done.

I hate when these damn threads get off track into the pvc/osha ****, ...

 

[darkk]

If you can get the SS for free, go for it. Otherwise just use Pex plastic. It will hold the pressure and it doesn't grenade if over pressured. The worst it does is split, pex is very forgiving and pretty tough.

 

[tool whore]

You have a big compressor! You're lucky with that and a large shop.

Dont monkey it up by trying to use pvc or cpvc regardless of schedule. See: Not for Pressure!

If you can get the stainless and the crimper/ or threader(I dont recommend threading it) then I would do it. 3/4" Type L copper would be best. Stainless IS GREAT for reducing the temps of the air, but adapting it to air lines can be costly.

I would stay clear of black pipe due to the labor involved and the losses. Copper is proper and pex (as mentioned: darkk) would be a very inexpensive solution.

For me it would be less about pressure loss and more about volume the system can carry. The loop is the better idea for a shop of your size. Various pipes and the amount of turns and fittings add up to pressure losses. Your compressor will make them ALL unnoticeable, period. Ask around at some shops. Without a gauge and a filled system you'll never know it. As for the volume, the bigger the better. Your comp can keep up with 2" copper loop, no problem. Spend the money on filters, dryers and oil removing devices (for painting cars). I see you have a drier. If you chose the pex I would suggest avoiding the lowes stuff and head over to a supply house and look for some 1" with the woven wire inside (x pattern) vs. the colored stuff. Turn your drops up before you bring them down to work areas (dirt leg) and this will make your system easier to filter and drain. Post pics. Best of luck. Remember, no glue!

 

[Frank The Plumber]

How much pressure is this compressor capable of making? 2" L copper is around $16 or more per linear foot. Not that 2" steel gas pipe is that much less expensive, but it is more durable.

 

[akdiesel]

Licensed to kill,
Go for the SS.
I am sort of a stainless freak. I did my 40' x 60' shop in 3/4" .035 wall SS. I have about 80' total length but not in a loop.
I have not had any problems with my system and it has been in service for about two years now. I used Swagelok compression fittings and the only issue I had was some samll leaks on some of the fittings, so I simply used some antisieze on all the furrels / threads and stopped the leaks.
I went one step further and used 1/2" .049 wall SS for my pressure washer line to get from one side of the shop to the other.
The installation is clean and will outlast anything out there.
On my main line I did not come off the top as suggested. I did install a second smaller tank (yes stainless) after my air compressor tank and the line enters the side of the tank and the main line comes off the top. There is a drain off the bottom for liquids. This is simply a knock out drum to help cool the air quickly from the J/T effect it gets from entering the lower pressure vessel. I have not noticed any water in my air drops or tools. I will be using a filter seperator for when I paint though for added protection.