how much does propane weigh per gallon?

Discussion in 'Propane - Got Gas' started by KJcachers, Apr 4, 2011.

  1. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    Finding the number around 4.24 pounds per gallon on the web but this creates a mystery for me. I just bought a new 20 pound talk at Costco with a gauge on it. Took it to have it filled and the pump showed it took 5.7 gallons? That comes out to 24 pounds in a 20 pound tank? To top it off the gauge on the tank isn't quite at full either. The guy at the store says a used tank being refilled normally holds 4.6-4.7 gallons which puts you at the 20 pound number so are brand new tanks really larger than 20 but there is always some left in the tank when "empty"???
     
  2. NJGuy

    NJGuy Active Member

    2,372
    1
    Apr 20, 2010
    Was the new tank purged first? 5.7 gallons does not sound correct.
     
  3. rabird

    rabird Howdy!

    6,128
    86
    Mar 3, 2006
    TX
    That's too much propane in a 20 lb cylinder.

    Weigh the full cylinder on a bathroom scale and subtract the TW (tare weight) stamped in the collar.

    Also note the WC stamped on the collar. You should only fill to 42% of the WC (a WC of 47 lbs * .42 = 19.7 lbs propane).

    Worthington Steel propane cylinder specs


    4.24 lb/gal @ 60F
     
  4. Flyfisherman

    Flyfisherman New Member

    My old notes say 4.11 lbs per gal @ 60 degrees ... and I believe that's at sea level(?)
     
  5. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    tank was new and prepurged and ready to be filled. going to weight it now. They had it on a scale at the fill station while they were filling it. I am thinking their gallon meter is off and I got overcharged.
     
  6. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    ok, weight on the digital scale showed 43.0 The TW is 19.8 and the WC is 47.60.

    Doing the math it looks like I got 23.2 pounds in the tank and should have only got 19.999 based on the WC. So now what? burn off some gas?
     
  7. Flyfisherman

    Flyfisherman New Member

    No. That tank has an overfill safety valve inside and only so much propane can be added. The tank is good to go as is. But it sounds like you really did get overcharged and I'd be calling them for an explanation. Tomorrow.
     
  8. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    the weight shows 23 pounds though? it was warm here today so would the temp have anything to do with it? it was mid 80's all day today in Northern Virginia!

    BTW, we have more than 1 station in town for fills so the next time I need gas I know where NOT to go!
     
  9. Flyfisherman

    Flyfisherman New Member

    I hear ya! It is impossible to put that much propane into a 20# tank. Whoever filled the tank is pencil wipping you! Like I already posted, there's a safety valve inside that tank, it's called an "OPD" valve (overfill protection device) and that will allow only so much propane into the tank. In fact, before that OPD valve became standard, when you had the tank filled you actually got more propane!

    Don't let that outfit get away with it. Call them, tell them you were over charged!
     
  10. rabird

    rabird Howdy!

    6,128
    86
    Mar 3, 2006
    TX
    The OPD is used as a secondary safety to stop filling not a primary.
    OPDs fail. I suspect your's is bad!
    Filling of 20 lb cylinders should be done by weight.

    The WC is water capacity FULL

    47.6 lbs/ 8.33 lbs/gal (water) = 5.7 gallons
    5.7 * 4.11 lb/gallon (propane @ 25C) = 23 lbs.

    If this FULL cylinder does not have any vapor space to compress if it warms above the 80F it was filled.

    If it were me, I'd take it back to Costco and get a replacement properly filled.
     
  11. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    I bought the tank at Costco a few weeks ago but just got it filled tonight. I do believe it was filled by weight as they had it on a scale while filling. so either their scale is off or their pump reading is off or they just put too much in the tank. I need to run the cook stove tomorrow and burn this thing down some and then reweigh it and see if things change.
     
  12. KJcachers

    KJcachers New Member

    1,361
    0
    Nov 30, 2010
    Where is Hank Hill when you need him? [LOL]
     
  13. rabird

    rabird Howdy!

    6,128
    86
    Mar 3, 2006
    TX
    Good luck.

    I can't get U-haul to fill by weight, they set it on a scale thry never adjust, but go by gallons or until the OPD shuts off.

    The ole time propane store does not have meter and must adjust the scale for each fill.

    It's clear to me your OPD is bad.
     

Share This Page