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Propane tank draw

I have a couple of 1000 gallon underground propane tanks. One of the tank is drawing and is now at about 20% full while one the other tank, the level needle has not moved in the last 3 month (shows at 80%). Not sure how Suburban has plumbed the tanks but they keep telling me that this is not unusual for one tank to draw while the other tank does not. Any advice would be appreciated!


  • Larry Weingarten
    Larry Weingarten Member Posts: 3,078
    Hello, I think some photos of how the tanks are interconnected to each other and the supply line would be useful. B)

    Yours, Larry
  • Intplm.
    Intplm. Member Posts: 1,476
    Photos can help.
    If suburban propane is saying that the situation is normal the photos that you take can be shared with this forum and suburban.
    The piping at first thought is my first guess but would only be a guess.
    JUGHNE Member Posts: 10,794
    Could be a defective gauge.
    Suburban may mean the gauge levels may not match as you draw down?
  • Leonard
    Leonard Member Posts: 903
    edited February 2019
    No experience with how tanks are piped...but I;ve worked with Freon. Propane has similar Temp/pressure curve to R12.

    1) Assuming tank vapor lines are connected so vapor can flow between tanks, either direction....... maybe one tank is little deeper, thus warmer (higher pressure). Propane might tend to come out of it 1-st. ( also , extra pressure might keep liquid propane in colder tank from vaporizing)

    2) Don't see why propane vapor couldn't condense ( transfer ) into colder tanks, unless tanks had something to prevent this ( checkvalves, regulators ....)

    (When designing new cars , engineers would tweak amount of Freon in A/C system and get performance optimized. Then to measure how much Freon is in system they would connect it to empty scuba tank sitting in dry ice. ALL the freon condenses into cold scuba tank. Then they weight it.)
  • Leonard
    Leonard Member Posts: 903
    edited February 2019
    Thought about it more. For safety EACH tank likely has a pressure regulator that reduces tank pressure to < 10 psi. ( don't want high pressure lines that can be broken when digging.)

    If pressure setting on each tank reg are slightly different seems tank with lower reg setting would not draw down untill other reg outputs less pressure.

    GUESSING manufacturing tolerance variations between 10 psi fixed regs might be ~1/4 psi ?? ( max)
  • Intplm.
    Intplm. Member Posts: 1,476
    Could be but a concern is a frozen line? Do you have one?
  • Leonard
    Leonard Member Posts: 903
    edited February 2019
    Heard FUEL propane has too much moisture to use as a refrigerant gas. NO experience.

    Anytime gas is expanded to reduce pressure it would get colder. Maybe frozen pressure reg?

    What's your weather been like ........ - 40 degs in Minnesota, or Florida?
  • lchmb
    lchmb Member Posts: 2,997
    is the shutoff valve open?
  • Gasmannnn
    Gasmannnn Member Posts: 1
    edited March 2021
    Hopefully it’s not a Quality Steel tank. Odorant fade is occurring in their new tanks.
  • ratio
    ratio Member Posts: 3,509
    Hopefully it was addressed some time in 2019, when the problem occurred‽
  • TAG
    TAG Member Posts: 751
    This is an old thread. Two years

    With various weekend places in PA for almost 30 years -- most with two tanks .. it was common to find one tank off after the guy filled. I was on auto delivery .... maybe this was a way so that at next delivery it was quick to fill only one tank.

    What would cause odorant fade ?