Gas on the boat - silly question,of the day

[Fr J Hackett]

No oxygen in the pipe! Also the laminar flame speed of butane is quite low, so even if you had the right mix, I suspect the flow rate out of the pipe would be too high for the flame to go back up it. I might give it go and see! (dont try this at home...)

When I was at school a long time ago we did a science open day on parents day, it consisted of various things made for experiments ( these were the days when science was an experimental subject and the bigger the bang the better); On of which was to show flame propagation down a tube, it consisted of about 15 M of glass tube stepped in diameter with an electric spark at the narrow end and a bunsen Berner feeding gas in at the other end when the tube filled with gas / air mix and reached the spark it ignited and the flame roared down the tube with a suitable large explosion / bang at the open end and the cycle repeated. I remember we had a lot of fun working out what diameter tubes we could use and how much gas we should be pushing down the pipe.
We had a bit of a nutter for a science master but he got me and one or two others hooked on science for the rest of our lives.

 

[Pete7]

OMG and you wonder why Calor won't supply you lot with portable gas cylinders

 

[DownWest]

OMG and you wonder why Calor won't supply you lot with portable gas cylinders

The tin trick won't work with butane, as it is heavier than air. We used coal gas back then, lighter than air.

PS, it might, as the butane would flow out of the bottom hole, whether air would get past the flame to get the mix right, not sure..

 

[Sandydog2]

As an undergraduate I was lucky to see an explosives lecture by Colonel Brian Shaw. He had by then been giving the same demonstration for about 60 years. I just looked him up and am delighted to find it was once recorded and is on YouTube.

Not long after we also had a similar demonstration by British Gas - it was also memorable but nowhere near as exciting.

 

[pyrojames]

The tin trick won't work with butane, as it is heavier than air. We used coal gas back then, lighter than air.

PS, it might, as the butane would flow out of the bottom hole, whether air would get past the flame to get the mix right, not sure..

Works best with methane. I haven't tried it with hydrogen....

 

[Ardenfour]

This property of gas, probably coal gas at the time, was spectacularly demonstrated by a science teacher when I was at school.
A golden syrup tin, with a press on lid, and holes in the base and lid was placed on a tripod stand with a bunsen burner under it. The gas was turned on, to allow the gas to flow through the tin, then lit at the top of the tin.
When the flame was stable the gas was turned off. The flame above tin continued for while, until the gas air ratio reached the Upper Explosion Limit, then the gas air mixture exploded within the tin and blew the lid off the tin with a loud BANG.
Probably against all the rules now, but very effective, I still remember it 60 years on.

Done similar with custard powder