jdc
Well-known member
In the light of the debate about whether it might be Butane or Propane or a mixture, it is essential to assume 100% Propane if subsequently transferring by weight gas obtained from a forecourt pump between bottles. See here for the relationship between weight of Propane and weight of Butane a bottle can safely take: Butane Capacity = Propane Capacity x 1.17
That way you may fill with a bit less than you could do, but it won't be over-filled.
However if filling from a forecourt pump the measure is volume not weight, ie in litres not kilograms. For this the gas composition is less important but one should allow for temperature (due to the very high coefficient of expansion of liquid Propane) to keep with the '80%' rule. This table shows the volumes which should not be exceeded.
However I can't say that filling one of the smaller cylinders is a good idea; better I think is to fill (always from empty) a 13, 19 or 47kg cylinder and then transfer, assuming Propane as I said above, to the smaller cylinders. And always round down by the likely measurement error in weight, volume or temperature.
For the avoidance of doubt I am neither advising filling from a forecourt nor advising against; I view transferring between bottles or from a pump rather like eating wild fungi - you best know exactly what you're up to and be on first name terms with the latin (or physics)! In a similar vein, you should treat these graphs and tables with caution and make some independent check of the numbers before just using them - I believe them correct but make no guarantee and would be pleased to be told of errors.
That way you may fill with a bit less than you could do, but it won't be over-filled.
However if filling from a forecourt pump the measure is volume not weight, ie in litres not kilograms. For this the gas composition is less important but one should allow for temperature (due to the very high coefficient of expansion of liquid Propane) to keep with the '80%' rule. This table shows the volumes which should not be exceeded.
However I can't say that filling one of the smaller cylinders is a good idea; better I think is to fill (always from empty) a 13, 19 or 47kg cylinder and then transfer, assuming Propane as I said above, to the smaller cylinders. And always round down by the likely measurement error in weight, volume or temperature.
For the avoidance of doubt I am neither advising filling from a forecourt nor advising against; I view transferring between bottles or from a pump rather like eating wild fungi - you best know exactly what you're up to and be on first name terms with the latin (or physics)! In a similar vein, you should treat these graphs and tables with caution and make some independent check of the numbers before just using them - I believe them correct but make no guarantee and would be pleased to be told of errors.
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