Uncle Bulgaria Posted October 19, 2012 Share Posted October 19, 2012 We are just back from a couple of months in Europe, during which time I topped up my refillable 11 Kg gas cylinder in Italy when the contents gauge showed the cylinder about half empty. I suspect that the LPG in Italy is butane, so I now have an approximately 50/50 propane/butane mix in the gas cylinder. We use the motorhome every month, even in winter, and I would welcome some guidance on how a propane/butane mix will gas off once the air temperatures drop towards freezing. The gas locker is well ventilated so I expect the locker internal temperature will be not much above the ambient. My current thought is to top up the cylinder again at a UK garage, so it should be with propane, and refill every time the cylinder gauge shows the cylinder to be half empty. This should dilute the proportion of the content that is butane. Is this a viable strategy, or should I fit the second refillable cylinder I have in place of the present one and fill from empty with propane? I'd then have a summer and a winter cylinder. Many thanks. Richard. Link to comment Share on other sites More sharing options...
flicka Posted October 19, 2012 Share Posted October 19, 2012 Hi Richard I think you have answered your own question. Eliminate any potential proplem & fit your "spare" refillable cylinder. Better to fill that with Propane now, (as presumably you will be filling it at some point anyway) Then you have your Propane/Butane cylinder for when the temperatures have risen. (it's not going to past any "sell / use by" date. 8-) Link to comment Share on other sites More sharing options...
Brambles Posted October 20, 2012 Share Posted October 20, 2012 With a 50% mix you have raised your boil temperature from approx minus 40 deg C to minus 25 degree C. If you just top up with propane as you suggest when next half full you will be diluting to 25% mix which is minus 35 degrees or there abouts for the boil temperature. You really do not have a problem or need to faff around with 2nd cylinder. Link to comment Share on other sites More sharing options...
Uncle Bulgaria Posted October 22, 2012 Author Share Posted October 22, 2012 First, apologies for the double posting. Brain fade is my excuse. My thanks to Flicka and Brambles. If we ever get down to the temperatures Brambles mentions then I think I'd have problems other than the gas mixture not boiling off. However, I am attracted by Flicka's recommendation because then adding back the second cylinder for extended winter operation will be easy as my installation was originally configured for twin refillable cylinders, but for most of the time one 11 Kg cylinder is more than enough so I went for a single cylinder to save weight and use the space freed up for other bits of essential kit. So two options, and I'm grateful for the advice. Richard. Link to comment Share on other sites More sharing options...
flicka Posted October 22, 2012 Share Posted October 22, 2012 Hi Richard Go for a better option - (if practical) remove Propane /Butane mixture cylinder for the winter period, fit the empty ? refillable & get it filled with Propane. Then you retain the weight saving & space. Store the Propane /Butane mixture cylinder until summer. Link to comment Share on other sites More sharing options...
Brambles Posted October 22, 2012 Share Posted October 22, 2012 Sorry Flicka, how can there be a better option when there really is in reality not a problem? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted October 29, 2012 Share Posted October 29, 2012 This is my understanding of the 'mix' of European autogas. LPG Composition (% by volume) as Automotive Fuel in Europe Country Propane:Butane Austria 50:50 Belgium 50:50 Denmark 50:50 France 35:65 Germany 90:10 Greece 20:80 Ireland 100:0 Italy 25:75 Netherlands 50:50 Spain 30:70 Sweden 95:5 United Kingdom 100:0 The higher the percentage of propane in the mix, the lower the ambient temperature that the gas will continue to vaporise at. You'll note from the above list that Italy is not the only European country where autogas has a high butane content, so (without knowing where, during your European travels, you refilled your gas-bottle and how much gas you put in each time) the propane/butane ratio of what's currently in your bottle is unquantifiable. Personally, I'd use up the gas (or at least most of the gas) that's currently in your bottle, then refill it with UK autogas. Even if there's currently a fair amount of butane in the mix it still should vaporise OK unless the UK weather suddenly turns artic. This just seems a tidier strategy than your 'half empty' dilution plan. If you are feeling paranoid, then fit your 2nd cylinder and fill it with UK 100% propane autogas. Link to comment Share on other sites More sharing options...
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