For years the gas companies have been using 'Ethyl Mercaptan' (the
rotten egg smell) as an odorant in propane. Ideally, when the propane
leaks you would smell it and as it is heavier than propane it
concentrates as the level of propane drops, thus becoming more
noticeable in cylinders that are nearly empty.
        It is known that rust and concrete can absorb the EC  odorant
and so leaks of propane in old cylinders and foundations may go
undetected.

                        David (dsl82wsty)

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>I've often noticed that as my propane tank runs out, I can smell a
>hint of gas outside the van.  When it's full no problem.  Am I
>imagining things?
>
>Jeff
>On 10-May-07, at 9:34 PM, Kim Brennan wrote:
>
>>For my AC work several years ago I bought a very nice HC detector.
>>Works to find leaks in the propane lines (or gas lines). Darn useful.
>>Helped me isolate a leaking fuel sending unit that had puzzled me for
>>a while. The human nose is only so good.