# Propane tank longevity **URL:** \ **Category:** Factual Questions\ **Created:** [February 4, 2009, 5:53pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444 "2009-02-04T17:53:06Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Gbro](https://avatars.discourse-cdn.com/v4/letter/g/c6cbf5/32.png) [@Gbro](https://boards.straightdope.com/u/Gbro)\ **Post date:** [February 5, 2009, 4:38am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/21 "2009-02-05T04:38:33Z")
> [@imfloating](#): > > How about…the colder the temperature, the less gas there is available ? You can help the boiling process some by tipping the cylinder thereby increasing the surface area of the liquid. Camp stoves have a cylinder stand just for this purpose. As for the question “how do we transport a 20lbs cyl. home” Well we will be guilty of doing things when we know them to be a bad Idea from time to time. I do have a pickup that I use almost all the time. And I am not a LP Gas professional by any seance of the word, But I have done many experiments with LP gas to better understand the products we use. I have some information on my web site. [http://www.nashwauk.net/UnderstandingOPDValves.html](http://www.nashwauk.net/UnderstandingOPDValves.html) and, [http://www.nashwauk.net/Exhibits.html](http://www.nashwauk.net/Exhibits.html) I have had this information reviewed by LP Gas Professionals and In one case they corrected misleading information on their site. Greg ---
**Author:** ![bluezooky](https://avatars.discourse-cdn.com/v4/letter/b/e8c25b/32.png) [@bluezooky](https://boards.straightdope.com/u/bluezooky)\ **Post date:** [February 5, 2009, 10:37am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/22 "2009-02-05T10:37:56Z")
> [@imfloating](#): > > I think your last sentence is the answer I’ve been looking for. I guess I was using the wrong terminology when I asked if the gas will last longer. It seems the warmer the temperature, the more gas there is available to be used. Ideally your supplier will change the mix of propane and butane for optimal performance depending on the expected temperature, it’s a subject of much debate whether or not the propane will evaporate off leaving the butane in the cylinder at low temps, I don’t have a definitive answer on this. ---
**Author:** ![masterofnone](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@masterofnone](https://boards.straightdope.com/u/masterofnone)\ **Post date:** [February 5, 2009, 4:07pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/23 "2009-02-05T16:07:38Z")
> [@Xema](#): > > Suppose you had an outside water tank. All the water is available down to a temperature of 0C (32F), at which point none is available. Would it be accurate to say “The the colder the temperature, the less water there is available” ? Sure, all of the propane is available until it freezes solid, but at low temperatures it may not have enough vapor pressure to be useful. See table #1 [here](http://www.propanecarbs.com/propane.html). ---
**Author:** ![old\_joe](https://avatars.discourse-cdn.com/v4/letter/o/58956e/32.png) [@old\_joe](https://boards.straightdope.com/u/old_joe)\ **Post date:** [February 5, 2009, 4:56pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/24 "2009-02-05T16:56:40Z")
> [@masterofnone](#): > > Sure, all of the propane is available until it freezes solid, but at low temperatures it may not have enough vapor pressure to be useful. See table #1 [here](http://www.propanecarbs.com/propane.html). Hmmm… i wonder how my bbq works in the cold then. I have barbied in temps down to -45f with no problems at all. Didnt notice that any difference in flame and it cooks just fine. I did know neighbours up north (Northern Canada) that used to place a troublelight under the large propane tanks that heated the home with a tarp to “keep them from freezing up” or so i was told. ---
**Author:** ![masterofnone](https://avatars.discourse-cdn.com/v4/letter/m/4bbf92/32.png) [@masterofnone](https://boards.straightdope.com/u/masterofnone)\ **Post date:** [February 5, 2009, 5:59pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/25 "2009-02-05T17:59:53Z")
> [@masterofnone](#): > > Sure, all of the propane is available until it freezes solid, but at low temperatures it may not have enough vapor pressure to be useful. See table #1 [here](http://www.propanecarbs.com/propane.html). Wow, did I mess that one up! What I meant was that all of the propane is available until it no longer transitions from liquid to vapor at -44F. Also, I should have added “for some applications” to the end of the first scentence to be completely accurate. I have run a propane heater and gas grill at well below zero, but some applications like my water heater require more pressure. ---
**Author:** ![imfloating](https://avatars.discourse-cdn.com/v4/letter/i/bc79bd/32.png) [@imfloating](https://boards.straightdope.com/u/imfloating)\ **Post date:** [February 5, 2009, 10:11pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/26 "2009-02-05T22:11:26Z")
I give up…but I’m thinking of venting my clothes dryer into the locker where the tank is. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [February 6, 2009, 1:20am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/27 "2009-02-06T01:20:05Z")
> [@masterofnone](#): > > … some applications like my water heater require more pressure. I agree that if we’re talking about something that consumes a lot of energy (e.g. a dryer) and if it’s connected with a small enough line, when the temperature drops low enough (say, meaningfully below 0F), vapor pressure may not be sufficient to force an adequate amount of propane to the appliance. ---
**Author:** ![imfloating](https://avatars.discourse-cdn.com/v4/letter/i/bc79bd/32.png) [@imfloating](https://boards.straightdope.com/u/imfloating)\ **Post date:** [February 6, 2009, 3:08am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/28 "2009-02-06T03:08:07Z")
> [@Xema](#): > > I agree that if we’re talking about something that consumes a lot of energy (e.g. a dryer) and if it’s connected with a small enough line, when the temperature drops low enough (say, meaningfully below 0F), vapor pressure may not be sufficient to force an adequate amount of propane to the appliance. So, I guess we can say that the answer to the original question in post #1 is…yes. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [February 6, 2009, 3:11am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/29 "2009-02-06T03:11:55Z")
> [@imfloating](#): > > So, I guess we can say that the answer to the original question in post #1 is…yes. Well, it has to be seriously qualified. The OP specified “constant rate” which doesn’t really allow this interpretation. And you need the conditions of very cold temperatures (likely below what was mentioned in the OP) small lines and high rate of consumption. ETA: Some googling reveals that a standard house propane regulator delivers a pressure of 11" of water, which is 0.4 psi. Propane maintains that vapor pressure below -20F. ---
**Author:** ![imfloating](https://avatars.discourse-cdn.com/v4/letter/i/bc79bd/32.png) [@imfloating](https://boards.straightdope.com/u/imfloating)\ **Post date:** [February 6, 2009, 3:45am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/30 "2009-02-06T03:45:04Z")
> [@Xema](#): > > Well, it has to be seriously qualified. The OP specified “constant rate” which doesn’t really allow this interpretation. And you need the conditions of very cold temperatures (likely below what was mentioned in the OP) small lines and high rate of consumption. > > ETA: Some googling reveals that a standard house propane regulator delivers a pressure of 11" of water, which is 0.4 psi. Propane maintains that vapor pressure below -20F. I think we’re forgetting here that I’m only trying to get hot water on a boat, not launch a space shuttle. All the different facts and opinions are very stimulating and enlightening. Enjoyment abounds while reading them, but I’m an Occam’s Razor type of guy. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [February 6, 2009, 3:53am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/31 "2009-02-06T03:53:54Z")
> [@Xema](#): > > Propane is sold by weight … Interesting. In my area it is sold by the gallon. I have a 500 gallon tank. I’m always confused about what it means, because I quite certain that the cylinder is not 500 gallons in volume. I’ve seen enough five hundered gallon plating tanks to know that the cylinder is probably about 200 gallons in volume. Nevertheless, I am currently looking at a receipt stating that I bought 150 gallons of propane a few weeks back. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [February 6, 2009, 5:42am UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/32 "2009-02-06T05:42:30Z")
> [@WarmNPrickly](#): > > Interesting. In my area it is sold by the gallon. Good point - when it’s not practical to weigh a tank before and after filling, it’s sold by volume. I believe the conversion is 4.23 lbs/gallon. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 6, 2009, 1:52pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/33 "2009-02-06T13:52:34Z")
> [@WarmNPrickly](#): > > Interesting. In my area it is sold by the gallon. I have a 500 gallon tank. I’m always confused about what it means, because I quite certain that the cylinder is not 500 gallons in volume. I’ve seen enough five hundered gallon plating tanks to know that the cylinder is probably about 200 gallons in volume. Nevertheless, I am currently looking at a receipt stating that I bought 150 gallons of propane a few weeks back. I have a 500-gallon propane tank buried in my yard, and I’m quite certain that it has a volume of at least 500 gallons. I took pictures of it before it was installed. If you bought 150 gallons of propane, you should have received 150 gallons of liquid propane. Note that propane is liquid under pressure. This [cite](http://en.wikipedia.org/wiki/Propane) from wikipedia states that: > [@](#): > > Thus propane…requires just 1,220 kilopascals (177 psig) of pressure to keep it liquid at 37.8 °C (100 °F). When you use propane, you are opening a valve at the top that allows the propane vapor to escape. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 6, 2009, 1:56pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/34 "2009-02-06T13:56:39Z")
> [@WarmNPrickly](#): > > …I have a 500 gallon tank. I’m always confused about what it means, because I quite certain that the cylinder is not 500 gallons in volume. I’ve seen enough five hundered gallon plating tanks to know that the cylinder is probably about 200 gallons in volume. Oh, and if I didn’t make it clear in my last post, either you are incorrectly estimating the volume of your tank, or you don’t have a 500-gallon tank. This is not rocket science. Gallons are gallons, whether you fill your tank with liquid propane or liquid water. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [February 6, 2009, 3:17pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/35 "2009-02-06T15:17:24Z")
> [@robby](#): > > Oh, and if I didn’t make it clear in my last post, either you are incorrectly estimating the volume of your tank, or you don’t have a 500-gallon tank. > > This is not rocket science. Gallons are gallons, whether you fill your tank with liquid propane or liquid water. Neither. I know what 500 gallons looks like. I just went out at measured it. It has a circumfrence of 10 ft and a length of 8 ft. That gives me a total volume of 340 gallons assuming no thickness of the walls. It’s larger than my eyeball measurement had it at. You can check my math if you like. The supplier has me listed as a 500 gallon tank, and it looks to be the exact same size of every 500 gallon propane tank I’ve seen. When we bought 300 gallons of propane this fall our tank was empty. The meter read 60%. I suppose it is possible that the propane company is overcharging me. In which case I ought to get this sorted out. If they are assuming I have a 500 gallon tank and they are using my meter to judge the amount of propane they are giving me, then I’m not being given the amount of propane I ordered. It still looks like every other 500 gallon tank I have seen. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 6, 2009, 3:50pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/36 "2009-02-06T15:50:43Z")
> [@WarmNPrickly](#): > > Neither. I know what 500 gallons looks like. I just went out at measured it. It has a circumfrence of 10 ft and a length of 8 ft. That gives me a total volume of 340 gallons assuming no thickness of the walls. It’s larger than my eyeball measurement had it at. You can check my math if you like. OK. Using your measurements, I get 476 gallons (assuming your tank is a cylinder). Usually the ends are rounded, so the actual volume will vary from I just calculated. Maybe you should check your math. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 6, 2009, 3:54pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/37 "2009-02-06T15:54:22Z")
> [@WarmNPrickly](#): > > …When we bought 300 gallons of propane this fall our tank was empty. The meter read 60%. On what basis do you think your tank was empty? > [@WarmNPrickly](#): > > …I suppose it is possible that the propane company is overcharging me. In which case I ought to get this sorted out. If they are assuming I have a 500 gallon tank and they are using my meter to judge the amount of propane they are giving me, then I’m not being given the amount of propane I ordered. It still looks like every other 500 gallon tank I have seen. They base how much propane they are giving you based on the meter on the truck, not your tank gauge. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [February 6, 2009, 3:56pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/38 "2009-02-06T15:56:50Z")
huh. I’ll have to check my math later. I don’t think I’ve had to calculate a cylinder volume in 20 years. Are my equations right? c = 2(pi)r r = c/2pi v = (pi)r^2\*h I got something like 44 ft^3, and that gave me 340 gal. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [February 6, 2009, 3:57pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/39 "2009-02-06T15:57:53Z")
> [@robby](#): > > On what basis do you think your tank was empty? They said “It’s empty”. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [February 6, 2009, 4:02pm UTC](https://boards.straightdope.com/t/propane-tank-longevity/484444/40 "2009-02-06T16:02:57Z")
> [@WarmNPrickly](#): > > huh. I’ll have to check my math later. I don’t think I’ve had to calculate a cylinder volume in 20 years. Are my equations right? > > c = 2(pi)r > > r = c/2pi > > v = (pi)r^2\*h > > I got something like 44 ft^3, and that gave me 340 gal. Your equations are correct, but you made a math error somewhere. C = 10 ft Therefore: r = 1.59 ft Therefore: V = 63.66 cubic feet Using a conversion factor of 7.48 gallons per cubic foot, you get 476 gallons. [Previous page](https://boards.straightdope.com/t/propane-tank-longevity/484444.md?page=1) [Next page](https://boards.straightdope.com/t/propane-tank-longevity/484444.md?page=3)