20 lb. Propane Tanks

Discussion in 'General Survival and Preparedness' started by Motomom34, Apr 5, 2017.

  1. Motomom34

    Motomom34 Monkey+++

    Propane tanks are something that I store. I have quite a few 20 pound cylinders. I found most of my cylinders at yard sales, paying around $5 each. I would then take the old tank into a propane exchange and get a new Blue Rhino or Amerigas cylinder. After reading and research, I now have less propane stored then I thought. Why? Because the propane exchanges are only putting 3.5 gallons of propane in the cylinder, it says on the label but I had never read the Blue Rhino label. If you go to an actual propane filling station they will fill your tank, using a scale therefore you will have more fuel in your stored tanks.

    Propane tanks also have expiration dates per regulation, places will not refill your tank if it is 12 years old. Some tanks can be re-certified but most (BBQ size) is easier to exchange. Have you checked your 20 and 40 lbs tanks?

    See example below:

    Are Your Grill Tanks Out of Date? | Holden Oil

    So I googled- how much does a gallon of propane weigh? Answer-

    1 gallon of propane weighs 4.2 pounds. A "full" 20 lb cylinder should have 4.7 gallons of propane in it.

    I thought I had roughly 4.5 gallons per tank but with discovering that the propane exchanges are putting less in, my propane storage is lacking, or not what I thought I had. I know it is shy a gallon but every gallon counts IMO.

    Further research led to to interesting info. I found the info below in the comment section of an article on propane.

    How To Tell How Full (or Empty) Your Propane Tank Really Is
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  2. ghrit

    ghrit Bad company Administrator Founding Member

    Good scoop. Note that most refill stations will fill by weight, tho' they may charge by the gallon. For refills that makes no difference to speak of, the conversion is straightforward, and the pounds to gallon conversion is corrected for temp. The reason for weighing is that propane's thermal expansion coefficient means that in hot weather you get less gallons than in cold weather, hence weighing is the way to make sure you get what you pay for. They are not supposed to fill to more than 80% (by volume, i.e., gallons) to keep the pressure down in summer temps. (Slight oversimplification there, but it works.) I don't know anything about these bottle exchanges (Blue Rhino and the like) so can't say how full a bottle might be. At the end of the day, the only thing that is affected by a short fill is how often you need to go to the refill station. (I like LONG time between fillups.)

    (Your bathroom scale is close enough to check up on how full. Not close enough to use for paying --)
  3. Kingfish

    Kingfish Self Reliant

    Propane storage is one of my main preps. I have about 75 of the little 1 pound cans for our camp stove. I buy them in 4 packs when they are on sale. I have entire totes full of them. I have a 500 gallon tank with 400 gallons in it. They fill it to 80%. I had it filled in 2009 never used it yet. It is hooked to my generator. I have a tee in the line and do all my test runs with a 100 pound cylinder. Those hold about 23.5 gallons. I have 4 of those now and a dozen 20 pounders. I did the same thing with old tanks. Exchanged them. Propane is great long term fuel .
    Motomom34, Tully Mars and Ura-Ki like this.
  4. Ura-Ki

    Ura-Ki Grampa Monkey

    Another thing to watch out for is when purchasing Diesel fuel or Jet-A make sure to tank up or have delivered on a cool day. Diesel and Jet-A will expand some 5% in hot weather. I have to be careful in filling, it's likely I will have a pretty good spill when the temps rise if I don't use it right away. Propane needs room for thermal expansion like Ghrit points out, it also needs to have a check valve for over pressure release. I rotate my tanks through the BBQ and Smoke house so that I can stay ahead of the expiration dates on the tanks. I didn't know about that when I first started out, now I look for the newest tanks I can find!
    Motomom34 likes this.
  5. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    The reason they use weight, instead of Volume, for Propane Sales, is Scales that meet Handbook 44 are a lot cheaper than Handbook 44 Liquid Propane Meters, and ALL Sales must be made with Devices that meet Weights & Measures NIST Handbook 44, and are Certified by each States Weights & Measures Authority as to Accuracy.
    Altoidfishfins, Ganado and Ura-Ki like this.
  6. Tully Mars

    Tully Mars Metal weldin' monkey

    Great post Moto!
    For those of us that get home delivery of propane, I have found that the delivery guy will recert your smaller tanks at the same time he refills your main tank. At least the companies around here will.
  7. Gator 45/70

    Gator 45/70 Monkey+++

    I had a 5 gallon jug filled two days ago
    The guy put 37# into it of propane
    and charged me 17.00 dollars.
    Mindgrinder, Ganado, stg58 and 2 others like this.
  8. SB21

    SB21 Monkey+++

    I usually take mine to be filled. You can exchange them for between to 15 to 20 bucks. I get them refilled for around 12 bucks. I only go to the exchange sites if I have an expired tank, because I have a hard time finding the time to go get them certified. But I have a 100 lb tank that I need to get certified so I may take a few in next chance I get. Some Tractor Supply stores around here refill them, that's the cheapest place I've found . I did hear someone tell me they were a member of some kind of camper place , not sure if it was KOA, Good Sam club, or what, but he said that as a member of that club , he could go to a camper supply store and on certain days they would refill your tanks for half price. Worth checking out. If I get a chance I'll pass this info on if it is indeed true.
  9. stg58

    stg58 Monkey+++ Founding Member

    Nice post.
    If I time it right when tanks are be filled and bring up a local event "hey how about that poor guy who drowned while fishing" as it is starting to tip the scale I can get a 101% filled tank...
    Most filling stations never check the certification date many minimum wage employees may not know about it but the exchange is a great way of getting a certified tank.
    We store 20# 30# and a couple 100#.
    Motomom34, Tully Mars and Gator 45/70 like this.
  10. stg58

    stg58 Monkey+++ Founding Member

    And by the way we transport and use our 20&30# tanks like this the crate adds a lot of stability and are easy to secure in the trucks.
    Cheap also:)

    Last edited: Apr 5, 2017
    3M-TA3, Ganado, Motomom34 and 8 others like this.
  11. techsar

    techsar Monkey+++

    I'm still trying to figure how gator got 8.8 gallons in a 5 gallon cylinder...:eek:
  12. Gator 45/70

    Gator 45/70 Monkey+++

    His scale is set at 37# tipping point, I stood there and watched him? I'll take it!
    Ganado likes this.
  13. oil pan 4

    oil pan 4 Monkey+++

    I sold my full 20lb tanks for $100 and used that to buy new 40lb tanks.
    If I can get 20lb tanks dirt cheap at yard sales I guess I should do that too.
  14. Bishop

    Bishop Monkey+++

    I get my tanks at the land fill people throw them out and the workers have them set aside so when I dump I pick up ,two on the way out I take my 100 pound tank to the camp ground and have it filled.
  15. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    I keep 8 - 20 pounders at my BOL because the travel trailer uses them. Late last year saw the purchase of a 100 lb cylinder with a travel trailer hookup for it. I'll likely purchase 3 more 100 pounders over the course of the next couple years.

    Found propane weight on the 'net and calculated that a 100 pound cylinder will hold 23.5 gallons. When filled it was squirting liquid out of the bleed screw at 23.4 gallons. Close enough. Tractor supply seems to have the best price, the 100 lb. cylinders and they can purge them.

    As noted by ghrit below, 23. 5 gallons doesn't allow for expansion.

    So from now on it's 19 gallons max for 100 lb cylinders.
    Last edited: Apr 5, 2017
  16. ghrit

    ghrit Bad company Administrator Founding Member

    Dangerous. Fill to 80% max. If the safety valve works, you won't do any damage unless the bleed off lights up, but you will waste a lot of propane.
    Bandit99 and Motomom34 like this.
  17. Altoidfishfins

    Altoidfishfins Monkey+++ Site Supporter+

    Seems to me I figured 23.5 gallons to be (80%) because I am aware of that (have to allow for expansion). Now the math doesn't work. Going to have to backtrack and find out where the senior moment occurred.

    I've already used a bit over the Christmas / New years week. So it's more than likely below that now. Either that or I have half of a travel trailer left. Haven't been up there since New Years.

    Appreciate you pointing that out.
    Update: it appears that you are correct ghrit

    At 4.2 lbs/gallon
    a 100 lb cylinder is full at 100/4.2 or 23.8 gallons.
    80% of 23.8 = 19.04 gallons

    So I shouldn't have had them put more than 19 gallons in the tank.
    Last edited: Apr 5, 2017
    3M-TA3, Motomom34 and ghrit like this.
  18. ghrit

    ghrit Bad company Administrator Founding Member

    Your tanks should have the tare weight on them as noted in the first post. With that known, you can easily put the tanks on a bathroom scale and tell if you are where you should be. Fill by the weight, pay by the gallon, and I do NOT know why it's done that way.
    Motomom34 likes this.
  19. oil pan 4

    oil pan 4 Monkey+++

    Sold by the gallon filled by weight.
    I suspect that the government is involved...
    3M-TA3 likes this.
  20. Cruisin Sloth

    Cruisin Sloth Special & Slow

    tank weight or TW /tare weight is 18Lbs & all 20 # of propane = 38# full
    All tanks have a TW stamped on them then add the tank size , so a 100# tank holds 100Lbs of LPG & the TW on mine is 81# , full they are 181 LB's. They are the same weight when 0c to 30c but pressure is max @ 30c of 135psig on a full tank . @ -35c (-21f) pressure is zero & no boil off happens. We use a different system to use LPG in - hell temps.
    I fill my own tanks from one valid date 100# into pigs & mini pigs ,30# & 20#
    Were in Litres & they say the BS that they Volume correct !! & yes government is involved
    Ganado and Motomom34 like this.
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