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propane gas line restricted, what came out?

PM Home and Cabin Services
PM Home and Cabin Services Member Posts: 23
edited January 2019 in THE MAIN WALL
In a seasonal cabin , replaced an antique direct vent wall furnace (never even turned old one on, customer just wanted to upgrade) with a similar type wall furnace. Cabin has propane tank with combination 2 stage regulator on tank, copper line buried underground apx. 20' then exposed below structure and into furnace. On startup, incoming gas pressure was 10" (same at regulator outlet at tank) yet when firing incoming gas pressure lowered to 3"and same for manifold, yet had 10" at regulator outlet. Determined there was some blockage? Checked for obvious kinks on exposed piping (found none). I disconnected copper line from both regulator outlet and furnace, used air compressor to blow line out. Could "feel" the air also was restricted blowing through, until it let loose. Once clear,reconnected and leak tested, supply and manifold pressure perfect . What came out is the question I have: the debris color was shiny emerald green, hard like stones yet crushed up with force. I first thought it was emerald ash borer beetles shells but that would be impossible because the tank and line have been in place for 40+ years (regulator was replaced by propane company a few years ago, but not left open to atmosphere at any point). Unfortunately, I did not take any pictures of the debris, unfortunately. Any one seen hard emerald green deposits build up and restrict copper propane line? I hope I described it well enough.
Thank you, Pat


  • Jamie Hall
    Jamie Hall Member Posts: 23,675
    Emerald green is a not unusual copper compound -- either oxide or sulphide. But which one, and how it got there, I'm not even going to try to guess. What I would say, though, is that that old copper line is now very suspect and probably should be replaced.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • lchmb
    lchmb Member Posts: 2,997
    I'll agree with Jaime.. dont know that it's an emergency but I'd start thinking about spring time..
  • PM Home and Cabin Services
    Line was pressure tested. Replacing the copper was recommended. will happen when ground thaws. Thanks for input and any more.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    I wonder if it was copper sulfide from impurities (sulphur) in the LP. Not sure if it were ever a problem in your area.

    If it were my camp, I'd put 100+psi of air to the line and trust it for this winter, but replace it in the summer. Sounds like it's all low pressure (inches WC). I always trun off the service valve at the tank when I'm not around for multiple reasons.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • rick in Alaska
    rick in Alaska Member Posts: 1,458
    The last time I saw something like that, it was the line dissolving. I am not sure what was in the propane that caused it, but I think it was actually multiple weird things. Either way, the line was almost eaten up. I would look closely at the inside of the line if possible.
  • Intplm.
    Intplm. Member Posts: 2,090
    LP and condensation, moisture in the copper pipe may have caused that. I have seen it. The green build-up. But not to the extreme that you described. WOW !
    JUGHNE Member Posts: 11,111
    When the NG pipeline came out west to us in the late 1960's, we were informed that no copper could be used anywhere in the system...only black pipe or appliance connectors.

    The reason given was that the sulfur/sulfides in the gas would cause flaking of the copper and be a problem in the gas valves closing completely.
    At the time NG was considered clean compared to LP.
    So there may have been some nasty LP many years ago.

    The NG company made an exception for copper though, they would bury it to the now long gone NG constant burning yard lights. (turned the meter 24/7/365)
    Although that copper had to be tin coated on the inside and IIRC could only be used outside the house. I do believe it is very expensive and maybe not available anymore.
  • PM Home and Cabin Services
    thank you for additional opinions. When it gets replaced, I will dissect old tubing, and post results. Cabin is rarely used, and tank is closed off when vacant as that is owners traditional process.
  • mikeg2015
    mikeg2015 Member Posts: 1,194
    JUGHNE said:

    The NG company made an exception for copper though, they would bury it to the now long gone NG constant burning yard lights. (turned the meter 24/7/365)

    They still exist. My neighbor has one running. I think he changes the mantle once a year. Maybe one of the last ones left in town. I had one I think at one time.

    My whole house had gas lights originally. Have 1/2" lines running all over. original lighting fixtures always have a female 1/2" threads to screw into the old pipe. One original 5 lamp ceiling fixture I have left was converted. Another 3 sconces were converted. I found a iron tool in the attic that turned the gas valves to the lamps.
  • GBart
    GBart Member Posts: 746
    From what I understand NG and LP as products are not very standardized, perhaps even the quality could be questioned.

    The gases themselves have no effect on copper, BUT additives for leak detection do as they tend to have sulfur, there was a statement that read -- G2414.5.2 specifies that Copper and brass tubing shall not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet of gas.

    Trouble is, how do you know that it's more or less? I also read that different parts of the country have different gas products just like gasoline and diesel and some are worse than others.