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The density of liquid propane (the main constituent of Autogas) is 582 kg/m3 or 0.582kg/l - so doubling the mass in kg gives a reasonable estimate of the volume in litres.


11kg equates to around 18.9l of liquid propane.

When this is evaported to a gas this would occupy around 6000l (at 20C).


The equivalent figures for Butane (a component of Autogas - around 10%) are:

Density: 601.4 kg/m3

Therefore 11 kg would be approx. 18.3l of liquid butane

Evaporation would give around 4500l of butane gas




PS - off topic

Why do they quote fuel consumption as miles/gallon rather than e.g miles/kg - petrol is less dense than diesel (and Autogas even lower density) - I suppose it is because we buy by volume rather than mass but it does result in the (incorect?) assumption that Autogas powered vehicles are less efficient than petrol, than diesel ...




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Hi, I recently purchased two Gaslow 11kg cylinders (mt) and the instructions that came with it for the GASLOW Cylinders are to fill no more than 22.5 litres per 11kg cylinder so for me 2x11kg cylinders would be no more than 45 litres of gas , Hope this is of some help,


NB... MY GASLOW CYLINDERS HAVE AN 80% GAS SHUT OFF VALVE, just bear that in mind when filling if yours are not the gaslow type.

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My Gaslow leaflet quotes a capacity of 21 litres for their 11kg bottle at 80% full, so it's difficult to see how one would get 22.5 litres in unless the Gaslow 80% cut-off valve varies in accuracy (or my leaflet's out of date!)


The propane/butane ratio of Autogas has no international standard. In the UK Autogas is (near as dammit) 100% propane, but elsewhere the ratio may significantly favour butane leading to potential problems in cold weather when Autogas is used for fuelling motorhome 'domestic' appliances.


The weight difference between liquefied propane and butane shouldn't matter provided that the bottle being filled has a cut-off valve that prevents it being over-filled. However (as Corky warns), if a gas bottle has no cut-off valve and there's no way of assessing how much LPG is already inside except by taking a preliminary measurement of the bottle's weight, then it's vital that you deliberately err on the side of under-filling rather than chance your luck by trying to maximise the amount of gas you can get into the bottle and still remain within 80% of its capacity.


Way back when, petrol was sold in the UK by volume in 'jerry-cans' and imperial units of measurement like the gallon and the mile were UK standards. Nowadays the UK is semi-metricated, with vehicle fuels being sold in litres, but the mile remaining the distance standard. On the Continent, where the litre is the standard volume unit and the kilometre is the standard distance unit, vehicle fuel consumption is quoted as Litres per 100km.


I can't think off -hand of an instance where a liquid in general use is marketed by weight rather than volume and I don't think people would be comfortable with the concept. (eg. a 1.25lb bottle of milk, rather than a pint). As petrol, diesel and LPG vehicle-fuels are all provided in liquid form, it would be peculiar to have fuel consumption expressed as a weight/distance formula, even if this did allow a comparison of relative efficiency.

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I would be very interested in how you get on, as I have only ever run out once since filling the first time and i have never been able to get anywhere near the original fill of 21/22 litres, I think the best i have managed is about 12/14 litres, I have only one 11kg bottle,


If you are still in doubt you could take the bottles our and weigh them, there should be a plate showing the actual bottle weight, so you only need to add/subtract the difference and that should be a reasonable indication of the amount of gas left.





hymer1942 - 2010-01-04 9:00 AM


Hi my problem is underfilling, so I am going to make sure they are both empty and then see what I get, I think I may have a dodgy return valve on one side. Thanks Barrie

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weldted - 2010-01-04 12:26 PM


i had two 11kg cylinder when they were first filled they took 20 litres each i ma

ke it 1 litre = .55kg. (when its empty its empty)


Yes Welted that is what I expected, but in over a year have only managed a realistic fill once, I have already been back to GLOWGAS and had one cylinder replaced. I am not impressed to say the least.

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hymer1942 - 2010-01-04 11:10 AM


Hi, I have spoken to Glowgas this morning and told them I intend to empty both, take them out and wiegh, then go to fill up and repeat and that should tell me something.. Will keep you posted. Barrie


It needs emphasising that there are significant risks involved in emptying LPG out of a gas-bottle.


I'm not going to offer advice how best to do this - just be bloody careful!!!!!

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Hi, Barrie


Do you need to fully empty the bottle, just my thoughts but, the bottle should be marked with its empty weight, so surly if you add 11 kg to that figure that should be the total weight of a fully filled bottle with 11kg of gas in it.


Therefore if you go to the garage and fill the bottle until the pump will not allow any more, then weigh the bottle, any significant weight difference between the bottle now and what it should be above will indicate just how much gas you have actually been able to put in (or not).


Hope that makes sense, only it does seem a waste just burning/running the heating etc just to empty the bottle.





hymer1942 - 2010-01-05 9:37 AM


Thanks Derek, at the moment I have the gas heating on in an effort to empty, so will carry on in this mode. Barrie

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Hi All just been out to the Van, and the guage on the right hand bottle is down to a quarter, should be empty overnight. The guages on these glogas bottles only start to work [ if at all ] when the bottle is below half full. The other one which I am almost sure is empty is still showing full even after a good shaking. Barrie
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