Tony Bryer wrote:
On Sat, 18 Jul 2009 22:01:57 +0100 Bob Minchin wrote :
We undertook an experiment in the first floor school science labs to see
if the water or gas supply had the highest pressure by connecting
them together one afternoon. The teacher kept lurking nearby so the
supplies were connect for quite sometime. We only got the real result
the next day when there were no school dinners. The cooks had tried to
light the ovens in the ground floor kitchen only to find that water was
coming out of the burners for some reason!

Our version - when the teacher went off for a cup of tea, leaving us to do
the lab work - was to get the bellows and pump air into the gas supply. In
due course a teacher from the next lab would come into to ask whether we
were having problems with the gas. Why yes, and such a disappointment to
us that we couldn't get on with our work.

Now that I know about purging gas pipework this probably wasn't the safest
thing to do, but I guess that bunsen burners don't really care.


I managed to prove to the others at school that my lung power was
greater than mains gas pressure once. I suspect it's not as dangerous
as purging requirements might suggest - I don't think a flame could get
down a bunsen jet against the flow of gas.

BTW - to the balloonatics - methane is the main component of natural
gas, molecular mass ~16. Air is a mix of nitrogen (~28) and oxygen
(~32) so while a natural gas balloon won't fly as well as a
mostly-hydrogen filled town gas one it should still work.

Andy