plumbing 4 air ?

[excelagator]

From Osha's Site. Maybe this will change peoples view.......

STATE OF WASHINGTON
Department of
Labor & Industries
Hazard Alert


For more information, call: 1-800-423-7233

FOR IMMEDIATE RELEASE May 26, 1988


PVC pipe not to be used in compressed air systems

OLYMPIA -- The Department of Labor and Industries warned today that plastic polyvinyl chloride (PVC) pipe cannot be used in compressed air piping systems without the risk of explosion.

When PVC piping explodes, plastic shrapnel pieces are thrown in all directions.

"We're seeing more incidents of explosive failure, and we're citing more employers for using PVC air system piping," said Paul Merrill, senior safety inspector in L&I's Spokane office.

"It's probably just a matter of time before someone gets seriously injured in one of these explosions unless everyone pays more attention to the manufacturer's warnings," Merrill said.

Last year, a section of PVC pipe being used for compressed air exploded 27 feet above a warehouse floor. A fragment of the pipe flew 60 feet and embedded itself in a roll of paper. Fortunately, nobody was in the area at the time.

A PVC pipe explosion in a new plant in Selah broke an employee's nose and cut his face.

PVC piping buried 3 feet underground at a Yakima manufacturing plant exploded, opening up a crater approximately 4 feet deep by 3 feet across.


---------------

Colonial Engineering Inc.
Thermoplastic Piping Systems



To Whom It May Concern:

From time to time, I receive inquiries as to the suitability of using PVC pipe land fittings in compressed gas piping systems. While the benefits of use may be enticing, it is a very dangerous and, in some states, illegal thing to do. For example, MIOSHA (Michigan's branch of OSHA) prohibits the use of PVC plastic in compressed gas systems unless properly encased in steel, cement, or some other approved material. Please check your local and state regulations.

The main problem with using PVC pipe and fittings for compressed gas is not that it spontaneously explodes but that PVC is a brittle material that can be broken or shattered with external force unless properly protected. Compressed gasses can be best described as being analogous to a coiled spring. When a PVC pipe or fitting fails when under stress from compressed gas it literally explodes like a bomb, sending shards of plastic flying several feet in all directions. Liquids, on the other hand, being compressed by only 1/10th of 1% contain very little stored energy. When pressurized systems with liquids fail, the energy is dissipated very quickly, thereby creating a much lower potential for hazard.

Colonial Engineering does not recommend the use of PVC plastic pipe fittings in compressed gas service.

If you have further questions regarding this matter please feel free to contact me directly.

Sincerely,

Jack Roach



From Osha's site here....

19880520 The Use of Polyvinyl Chloride Pipe in Above Ground Installations

I looked up this a couple years back. I have too wide temperture changes here and if oil gets in the line it will weaken the PVC. Personally I would not run PVC. The dangers are too great IMHO!

[JSharp]

Originally Posted by ray66v

Not all install's are professional. We had such an up flow system in my body shop. However, we put it in our selfs.
An up flow system can work, however the first sign of water in the air, is when the main trunk line is loaded with water, rather than a small amount in the drop line. If you reach this point, you have to bleed out the system to drain the trunk. Shutting down production while the air supply recovers, add to that the noise of such a bleed down, (+115db) and the mess. We changed it to a down flow and were much happier.
These problems are exacerbated by very high volume use of the air supply. If you don't intend to use a lot of volume, and can be very diligent about draining the condensate you may not have much trouble with an up flow.
A good drier after the compressor is always a good way to eliminate all these problems.

Upflow at the taps is the correct way to do it. The main line is high at the compressor and sloped away ( far end lower ) with a vertical down leg at the end for draining. The branch runs are done the same way. Connected at the top of the main line and sloped away with dip legs at the end of each and the final taps for hose or equipment connection above the bottom of the line. Every vertical should have a valve at the bottom for draining.

Comments on the thread in general - I'm surprised at all the people who want to save a few bucks and use plastic. Use black iron pipe instead. Skip eating out one or two nights and do it right. It'll be money well spent.

I say that after working with air compressors up to 500HP and running thousands of feet of industrial airline in my life. I'd never use plastic. And I love using plastic for things where it's properly selected and engineered. But IMO there are too many potential problems with it in this application. Not the least of which are -

Oil and chemical compatibility issues.
Strength, shock and vibration issues.
Loss of properties at temperature extremes.
Lack of sunlight resistance.

Threaded black iron pipe just isn't that hard to work with or that expensive. Done properly it'll outlive the installer..

[ray66v]

Originally Posted by JSharp

Upflow at the taps is the correct way to do it.

Yes, your referring to a take off, from the trunk that goes up, and then vertically down the wall. I seen it done this way, and agree. (Unless I misunderstood your point).

The up flow I was referring to, was a trunk running low, perhaps along the floor, with take offs going up the wall. Sorry, if I confused / frustrated anyone with this.

[JSharp]

Originally Posted by ray66v

Yes, your referring to a take off, from the trunk that goes up, and then vertically down the wall. I seen it done this way, and agree. (Unless I misunderstood your point).

The up flow I was referring to, was a trunk running low, perhaps along the floor, with take offs going up the wall. Sorry, if I confused / frustrated anyone with this.

Right.

A vertical at the compressor to the high point of the horizontal overhead main and branch lines.

[patrick_g]

Any of you experienced pros want to share a little knowledge with me?

I'm going to be putting in a new stationary vertical air compressor to be shared by our shops (my ground floor wood shop and metal shop plus drops to adjacent garage for tires) and want a run to the second floor above the wood shop (half is the wife's ceramics and hobby shop and the other half is mine but not dedicated to a specific purpose yet.)

Is there a recommended way to plumb the run upstairs? Any issues? With no credible objections I will just run a vertical up there with an inverted "U" to a drop with dual outlets and a "tail" to a drain valve. Down below the vertical run will have a path to a drain so there will be no water reservoir.

Pat

[JSharp]

Originally Posted by patrick_g

Any of you experienced pros want to share a little knowledge with me?

I'm going to be putting in a new stationary vertical air compressor to be shared by our shops (my ground floor wood shop and metal shop plus drops to adjacent garage for tires) and want a run to the second floor above the wood shop (half is the wife's ceramics and hobby shop and the other half is mine but not dedicated to a specific purpose yet.)

Is there a recommended way to plumb the run upstairs? Any issues? With no credible objections I will just run a vertical up there with an inverted "U" to a drop with dual outlets and a "tail" to a drain valve. Down below the vertical run will have a path to a drain so there will be no water reservoir.

Pat

I don't see any problem with that. In effect you treat both systems as if they're independent, proper slope, drainage, etc. Then add the connection between the 2 as a "drop" in the first system and as the initial feed in the second.

As you get farther from the compressor you'll have greater cooling and additional water, especially with a connection between the buildings. It's not a big deal though with proper installation.

[patrick_g]

Jsharp, Thanks for the reply. I thought I had the bases covered but we all know when we are the most dangerous (when we don't know that we don't know!) so thought I'd get a sanity check before plumbing.

P.S. It is all one building or at least connected. Think attached two story garage with single story 21x48 on the side so all plumbing remains indoors.

Thanks again.

Pat