"Loren Amelang" wrote in message
...
On Sat, 11 Dec 2004 17:37:59 -0700, "Bill P" wrote:

Somehow in real life I've never found that to be true. NG is lighter
than air and mixes well with it, but propane is heavier than air and
doesn't want to flow up and out of the burner.

Loren... Isn't NG a bit heavier than air (N+O2)? Why does it collect
in missle silos (sp) rather than float up and out when the doors and
vents are open?
Just wondering...
Bill

Well, I hadn't _really_ checked the exact numbers, so...
http://www.engineeringtoolbox.com/22_334.html

Air 1.000
Butane - C4H10 2.067
Ethane - C2H6 1.049
Ethylene (Ethene) - C2H4 0.975
Methane - CH4 0.554
Natural Gas (typical) 0.660

I think the answer to your question is similar to one of the comments
about propane - "natural gas" can include a lot of heavier components
along with the methane. For sure, the methane will rise out of the
silo, but just about any other flammable component will stay down.

Loren

Appreciate the info! I guess for the sake of limited paper space in
the article I read some time ago, the author was either ignorant him
self or had to cut down on article size hence making the statement
'methane gas collected in copious quantities missle silos and detection
devices were mandatory....'

thx again Loren!!

Bill