(206) 949-5683, Top Rated Plumber, Seattle
Page 2 of 3 FirstFirst 123 LastLast
Results 16 to 30 of 38

Thread: PVC and Compressed air

  1. #16
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,615

    Default Pvc

    In that case copper might be cheaper.

    I've had PVC in my residential garage for compressed air going on ten years. It's ASTM D1785 Schedule 40 and in 1/2" size rated for 600psi
    That makes as much sense as saying that you have had a male lion living in your house for 10 years and there is no way it will attack and kill you. What happened up until today, has no bearing on what could happen 10 minutes from now. And the older PVC pipes get the more fragile they become.
    Last edited by Terry; 10-22-2008 at 04:29 PM.

  2. #17
    DIY Member msgale's Avatar
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    90

    Default aha, the compressed gas willexplode the pipe if it bursts,..

    whereas the water will just split it w. no major force .

    good point.

    thank you. now i feel better.

  3. #18
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Quote Originally Posted by hj View Post
    In that case copper might be cheaper.

    quote;
    I've had PVC in my residential garage for compressed air going on ten years. It's ASTM D1785 Schedule 40 and in 1/2" size rated for 600psi

    That makes as much sense as saying that you have had a male lion living in your house for 10 years and there is no way it will attack and kill you. What happened up until today, has no bearing on what could happen 10 minutes from now. And the older PVC pipes get the more fragile they become.
    The rating of the pipe is 600 psi. There is a safety factor on top of that; let's ignore that for now. My compressor shuts off at 80 psi, so the pipe is 7.5 times stronger than it has to be.

    For your analogy to make sense the lion has to be 1/7.5 times my size, or about 21 pounds. Lot of folks have cats that size.

  4. #19
    Geologist sjsmithjr's Avatar
    Join Date
    Dec 2005
    Location
    Knoxville, Tennessee
    Posts
    295

    Default

    Quote Originally Posted by Southern Man View Post
    My compressor shuts off at 80 psi, so the pipe is 7.5 times stronger than it has to be.
    The OP specifically stated an operating pressure of 100 psi.

    The American National Standards Institute/American Society of Mechanical Engineers limit the operating pressure of PVC to 100 psi and prohibit the installation of such systems unless the above ground portion is encased in conduit or casing.

    The Plastic Pipe Institute recommends against the use of PVC for compressed air (or other gas) in exposed piping.

    ASTM says no to the use of PVC for compressed air in exposed piping.

    OSHA says no to the use of PVC for compressed air in exposed piping. It's use for this purpose has resulted in serious injury.

    The industry as a whole says no to the use of PVC for compressed air in exposed piping. Anyone giving advice to the contrary is just plain wrong.
    Last edited by sjsmithjr; 10-22-2008 at 04:33 PM. Reason: Trying to keep it civil.
    -Sam Smith
    Licensed Professional Geologist - AL, TN, KY

  5. #20
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Quote Originally Posted by sjsmithjr View Post
    The OP specifically stated an operating pressure of 100 psi.

    The American National Standards Institute/American Society of Mechanical Engineers limit the operating pressure of PVC to 100 psi and prohibit the installation of such systems unless the above ground portion is encased in conduit or casing.

    The Plastic Pipe Institute recommends against the use of PVC for compressed air (or other gas) in exposed piping.

    ASTM says no to the use of PVC for compressed air in exposed piping.

    OSHA says no to the use of PVC for compressed air in exposed piping. It's use for this purpose has resulted in serious injury.

    The industry as a whole says no to the use of PVC for compressed air in exposed piping. Anyone giving advice to the contrary is just plain wrong.
    600/100 = factor of safety = 6. But that ignores the factor of safety of the rating, which is probably 2, so that the actual FOS = 12. That big ol' lion in the house is now very small indeed. For a system used intermittently in a residence I see no problem.

  6. #21
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007
    Location
    Connecticut
    Posts
    7,463

    Default

    Quote Originally Posted by Southern Man View Post
    600/100 = factor of safety = 6. But that ignores the factor of safety of the rating, which is probably 2, so that the actual FOS = 12. That big ol' lion in the house is now very small indeed. For a system used intermittently in a residence I see no problem.
    http://www.osha.gov/dts/hib/hib_data/hib19880520.html

    http://www.osha.gov/pls/oshaweb/owad...ONS&p_id=20202

    And you my friend are the recipient of todays award!



    It always amazes me that someone when presented with overwhelming evidence that the position they have taken is wrong, and the opinion is shared by many others will continue to argue their point...

    There must be a word for that...
    Last edited by Redwood; 10-22-2008 at 06:36 PM.

  7. #22
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,615

    Default Pvc

    You are quoting a rating for PVC when it was new. As it ages it becomes brittle, and will rupture at a much lower pressure. Few compressed air systems work at more than 125 psi, but there have been countless failures of PVC air systems, ALL using schedule 40 or 80 pipe, occassionally with fatal results. But I guess what we should have done is say, "DON"T DO IT!" and then let you do whatever you want to. I guess saving a couple of dollars in material costs is MUCH more important than having a safe installation.
    Last edited by hj; 10-23-2008 at 07:35 AM.

  8. #23
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    OSHA regs don't cover homeowners.

  9. #24
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    Quote Originally Posted by hj View Post
    You are quoting a rating for PVC when it was new. As it ages it becomes brittle, and will rupture at a much lower pressure. Few compressed air systems work at more than 125 psi, but there have been countless failures of PVC air systems, ALL using schedule 40 or 80 pipe, occassionally with fatal results. But I guess what we should have done is say, "DON"T DO IT!" and then let you do whatever you want to. I guess saving a couple of dollars in material costs is MUCH more important than having a safe installation.
    PVC gets brittle how, exactly? Sunlight, right? There's not much of that on the ceiling of my garage. Maybe you should check where the failures have occurred. My guess probably during testing, and a pipe was nicked or weakened by the guy installing it.

  10. #25
    Engineer Furd's Avatar
    Join Date
    Jul 2007
    Location
    Wet side of Washington State
    Posts
    446

    Default

    I had a PVC compressed air distribution system in my garage workshop some 35 years ago. I never had any problems with it but that doesn't mean it was safe. One thing that I did was to have a flexible hose between the compressor storage tank and the fixed piping to eliminate vibration and stress on the PVC. Very early on in the use of PVC piping it was discovered that repeated vibration OR stress induced by forcing PVC piping into alignment was a major cause of early failure.

    When I learned that Washington state (through the bureau of Labor and Industries) had prohibited PVC in compressed air systems I discontinued using the PVC air line in my shop.

    In my NOT so humble opinion, given the results of years of testing and the high failure rate of PVC piping in compressed air systems, only a fool would use PVC for compressed air.

    There is another possible factor in the high failure rate of PVC compressed air piping and that is that all oil-lubricated compressors have a certain percentage of the lubrication oil carry over to the air. There is no doubt whatsoever that petroleum products are detrimental to PVC. Just one more reason not to use PVC for compressed air systems.


    I'm quite sure there are hundreds of home shops that have PVC piping in compressed air distribution systems and they have had no failures. I personally know of someone that installed a PVC distribution system and even after I told him of the Washington state prohibition he dismissed the danger just as Southern Man is doing. Just because some people are lucky is no reason to tempt fate.
    Last edited by Furd; 10-23-2008 at 12:33 PM.

  11. #26
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Location
    Yakima WA
    Posts
    7,246

    Default

    I liken this discussion to what many woodworker make when rationalizing the non use of blade guards and splitters on their table saws, or some drivers make about seat belts. They feel since they have not used a blade guard in (fill in the years) they some how are immune to the danger, or they have been driving for 50 years and never have need a seat belt. You can make all the BS excuses you want, PVC is not a safe material for compressed air and it's stupid not to buckle up. Southern Man, you can use all the PVC you want in your shop for compressed air, but please do not advise others to do so.

  12. #27
    DIY Hillbilly Southern Man's Avatar
    Join Date
    Jun 2008
    Location
    North Carolina
    Posts
    530

    Default

    The system isn't used very often and when it is charged, is connected via a rubber hose and quick connects. The oiler is located on the end near my bench so doesn't contaminate the system that can be used to inflate tires. Comparing it to driving without a seat belt or cutting wood without a guard, or owning a live lion is rather silly but if it make you feel good I'm happy for you.

  13. #28
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Location
    Cave Creek, Arizona
    Posts
    25,615

    Default Osha

    Just because OSHA rules do not apply to homeowners, does not make it safe to disregard their advice. Your best source is to call your state's industrial safety division and ask them if there have been any incidents in your area of bursting PVC air lines, because obviously you are not going to believe us. I hope you do not do your own plumbing systems, because few people with your "I can do what I want to", attitude install them correctly.
    Last edited by hj; 10-23-2008 at 08:22 PM.

  14. #29
    Engineer Furd's Avatar
    Join Date
    Jul 2007
    Location
    Wet side of Washington State
    Posts
    446

    Default

    Southern Man, you claim to be a civil engineer. Would you not adhere to ASTM specifications for reinforcing steel in a bridge you designed?

    Would you ignore the specifications for a steel I-beam used to support some structural part of a building that was being remodeled to open up a room? How about if the building was a residence that had lally columns in the basement holding up the main floor and the architect had a structural engineer calculate a specific steel to spread the load to the outside walls. Would you just substitute a steel stud because steel is steel?

    How about a gas grill connected to a natural gas line? Would you use a piece of air hose that had a 200 psi maximum use pressure with a 800 psi burst pressure? Would you justify that usage by saying that the natural gas is less than 1/2 psi pressure? Would you use a piece of garden hose to connect a furnace to the gas line using the same justification?

    Admit it, you don't give a damn about specifications when the specifications might somehow inconvenience you. I's glad you live on the other side of the country from me and I will never have to subject myself to ANYTHING you might have had a part in engineering. In short, you are a disgrace to all engineers.

  15. #30
    DIY Member Steve_P's Avatar
    Join Date
    Oct 2008
    Location
    East TN
    Posts
    41

    Default

    the pressure rating of PVC and the resulting factor of safety is meaningless. The fact is that PVC is NOT intended for compressed air use and the makers state that. I'm sure there are miles of PVC being used in compressed air systems in people's garages, but it's still not a smart thing to do. Catastrophic failure will not be friendly to anyone around. The only time I would ever consider using PVC for compressed air is if it was buried underground- where failure couldn't cause personal injury.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •