On 11/12/2014 3:46 PM, Don Phillipson wrote:
delphiprog wrote:

is there a "safe" amount of natural gas to
smell? Reason: I can smell natural gas near my meter, but only when I
put my nose right near the pipes. Anywhere else along the ground
around the meter I can't smell it - and I can't smell it on any of the
pipes in my house that I could reach

No "safe amount" of any explosive gas can be detected
by human nose. Our noses have not been trained to
discriminate between safe and unsafe odours. This is
why gas companies ask people to notify them if they
ever smell gas.

Natural gas has no detectable odor at all -- it's only the mercaptan
oderant added that can be detected by the nose. It's so strong simply
so that a tiny amount is detectable by almost everybody (albeit I can
often not notice the trace amounts spoken of above when some others
claim it smells strongly of it to them; my sniffer ain't so hot as some
I gather).

The measurement devices used by the gas co aren't "smelling", they're
using active sensing to detect the actual methane/propane/whatever...

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