LPG In Cold Weather

Discussion in 'Tech/Mech General' started by veletron, Dec 24, 2009.

  1. veletron

    veletron Read Only Funster

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    Hi

    Has anyone had trouble with using LPG in cold weather?

    My tank (underslung) is full, but I cant get any gas out of it from the cooker, fridge etc. Basically, the gas does not appear to be boiling (gassing).

    I know this is an issue with butane, but LPG is 95% propane, and thus there should not be an issue!

    I was in europe in the summer where the butane content is higher, so there is likely a good deal more butane than the ~5% that apparentely goes into LPG in the UK. However, as far as I know, the butane content wont gas, but the propane content will, so whatever the temp, and even if (discounting 80% cutoffs) there is 10L of Butane in a 20L tank, there should still be 10L of combustable propane available...

    At the moment, it looks like I have to cancel a planned trip to Mull as I cant cook or heat the van or water etc!

    Rather anoying! My only other route is to ditch the underslung tank and go back to using bottled, but thats a days work at least!

    Anyone offer any advice?

    Nigel
     
    Last edited: Dec 24, 2009
  2. RichyB

    RichyB Read Only Funster

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    Hi,
    Yes, I'm experiencing problems at the moment. My LPG system is working ok, but is causing a strange sickly smell inside the MH. According to others, the smell isn't uncombusted LPG, but it is a strong sickly smell (like pooh!), noticable only when the heating is working. I've got it booked in with Truma for early Jan to be checked over. The problem has only appeared since this really cold spell. it was working fine before.
     
  3. Braunston

    Braunston Read Only Funster

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    Hi,

    Be very very careful, as while CO has in itself no smell quiet often the process of production/making it does, i would certainly get it checked before you attempt to use it again, may be a bit over cautious but you only live once.





     
  4. scotjimland

    scotjimland Funster Life Member

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    Depending on where you bought your LPG it it could be a 50/50 mix .. (see quote) but all that is a bit academic..

    I can only suggest buying a propane bottle and Teeing into the line either before the LPG regulator using a propane pigtail,( such is used on RVs using an ExtendaStay fitting ) or after the tank regulator using a bottle regulator ..

     
    Last edited: Dec 24, 2009
  5. veletron

    veletron Read Only Funster

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    Hi

    2 Weeks ago after having similar issues, I put 10L in the tank (20L tank -> 16L with 80% cut-off). Could have been 6L of pure butane remaining in the tank at time of refill.

    That 10L should have been close to 100% propane. Bought at a shell garage in Stirling, Scotland, I would at least expect a 'winter mix'.

    I guess I can re-install a propane bottle together with the old 30mBar regulator and then have a changeover valve under the sink where the gas manifold is. The regulator on the external tank is under the van next to the tank. The changeover valve would fit before the manifold under the sink...

    Looks like a delayed holiday...!

    Nigel
     
  6. scotjimland

    scotjimland Funster Life Member

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    Sounds like a good plan Nigel ..

    another option is to fit a BBQ take off point, that can be used to connect the propane bottle ..

    jim
     
  7. veletron

    veletron Read Only Funster

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    Now thats an idea worth thinking about longer term. I'm gonna pick up a cheapy stand-alone camping stove for the meantime.

    Nigel
     
  8. ocsid

    ocsid Read Only Funster

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    As is realised with using auto LPG that is targeted at liquid take-off systems we have a serious issue with our vapour take-off systems in that the Butane part "bulks-up" in the storage tank.
    As the vapour pressure of butane is lower than that of propane throughout our ambient range, then we are never using our butane whilst we have any of the propane left.

    So even in the summer it could not be being used up if we habitually keep topping up.

    Therefore we have to deplete our storage tank(s) at times when the butane can be used [basically >6C for free-gassing] if we want to enter the winter months with high capacities of propane.
     
  9. Snowbird

    Snowbird Funster Life Member

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    You say your regulater is external on your tank.
    As with US RVs it is not unheard of for the regulater to get gummed up,or frozen.
    I think they discharge at times,becouse mine has a wire mesh on it that does from time to time give problems.
    My regulater is directly in line with all the crap that the wheels throw up so I had to fit a guard to deflect the crap.
    First check around the regulater,before you do anything.
    We have been in temp of minus 15c and the tank has not frozen.
     
  10. olley

    olley Funster

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    Hi this problem seems very curious, none of the technical details regarding propane/butane mix, agree with what some motorhomers believe. All the ones I have found just say that the two gases mix and depending on the ratio reduce or increase the boiling point, see here for one: http://www.engineeringtoolbox.com/propane-butane-mix-d_1043.html

    If you look at the chart a 50/50 mix has a boil temp of -20F/-28C so if the outside temp dipped to say -10C I wonder if as you drew the gas of, its temp would drop to close to this figure? I believe they reported temps of -16C yesterday in the Sottish Highlands. Only way to tell would be knowing the mix and measuring the tank temp.

    Very wasteful I know, but if it was me I would go somewhere quiet but windy, and blow the gas off, and then refill, hoping to get a mix of more propane to butane

    Olley
     
    Last edited: Dec 24, 2009
  11. ocsid

    ocsid Read Only Funster

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    Very interesting Olley and thanks for the link; however my user experience puts me in the camp that thinks that the propane boils off first. Something is certainly choking up the gassing off when things get cold.
     
  12. scotjimland

    scotjimland Funster Life Member

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    Hi Olley.. good link ..

    Irrespective of the temperature, the SG must play a part when the two gasses in the liquid state are in storage, from your link..

    SG of Butane - C4H10 2.0061

    SG of Propane - C3H8 1.5219

    That would suggest to me that the as the liquid Butane is almost 25% denser it will settle to the bottom of the vessel.. ?


    jim
     
  13. olley

    olley Funster

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    Hi Jim the SG would play apart if, the two liquids didn't mix, but from what I have read they do, bit like putting antifreeze (ethylene glycol) in your engine, it mixes nicely with water.

    If you look at that link at a 50/50 ratio at 32F you only have 7.6psi, at -10F its only 3.5psi, which would give problems I would have thought as our regulators are set at around 28mbars or 4psi.

    A case where the science doesn't match our experience, but maybe we expect to much, and the science is correct.

    Olley
     
    Last edited: Dec 24, 2009
  14. scotjimland

    scotjimland Funster Life Member

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    Hi Olley .. good academic discussion for Xmas eve :Laughing:

    Here is a good link with plenty of stuff to digest.. which would support your argument ..
    FAQ - Fuel Mixtures

     
  15. ocsid

    ocsid Read Only Funster

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    Olley your scientific findings that seem to run counter to what we know happens in practice got me doing a bit of research and I found another interesting article.

    http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm

    Reading the bit, "operation of an upright stove" is particularly relevant.

    What the article supports is both the scientific you found and the real life we find:
    Indeed the vapour pressure of the mix is effected by the mix ratio, but in use the propane does in fact deplete faster than the butane. Some of the butane does come off at below butane's gassing temperature but only whilst there is some of the fast depleting propane.

    Worth a read. Cheers John
     
  16. olley

    olley Funster

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    Hi john very interesting link, thanks, it would appear that while the propane boils off, the butane streams off at a slower rate, so over time the ratio of propane to butane changes.

    Then the only answer is to provide some form of heating, maybe a few turns if 8mm copper pipe wound around the tank, with hot water being circulated through it. mind you if the tank ain't gassing how do you heat the water?:Smile:

    Olley
     
  17. Landy lover

    Landy lover Funster

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    Interesting thread this - we are parked up now for a month or 3 for the winter and hooked up to a 47Kg propane Bottle. The other night I had to change bottles yet I know there are a couple of Kg left in it . The one I am now hooked up to has a layer of ice on it at least a inch thick - the temperature outside is about -7 C and we have had freezing fog and strangely a couple of minutes of rain which promptly turned all about into a skating rink - So as I understand it pure propane gases at -42 C and butane at 0 C and the normal Propane /Butane mix gases down to -20 are they for any reason adding more butane to the bottle gas /autogas these days ? it used to be 90% propane 5% butane and 5% other gases. I cannot find any info on that apart from the fact that as been said on here that in warm climates they will go up to 50/50 which I would have thought would automatically bring the gassing point closer to 0 C
     
  18. veletron

    veletron Read Only Funster

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    Hi all, and thanks for all the input.

    I've just been out under the van and undone the regulator from the tank - turn the tap, and I can hear gas so I think I've been barking up the wrong tree.

    Connected that back up and undid the other side, and nothing comes out.

    I've put the regulator on top of a radiator, and a whole load of water coming out of it was the result. It must have gotten trapped in there and frozen. I suspect this has damaged the membrane also. After defrosting, I was able to blow through the regulator again.

    Question is - how the heck does a regulator get full of water? I thought I bought LPG from the local garage, not an LPG/water mix!!

    I'll stick it back together later and see what happens, but I'll change the regulator anyway.

    Nigel
     
  19. Snowbird

    Snowbird Funster Life Member

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    Check my earlier post, It gets in from the road splashes.
    I had same problem.
    We somtimes get to technical.:thumb:
     
  20. scotjimland

    scotjimland Funster Life Member

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    yes indeed,

    but it broke up the monotony of the crap served up on Christmas eve TV ..

    jim
     
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