Geek content ... 'cutting' your meths.

[Bearbonesnorm]

Just out of interest I thought I'd have a little mess about 'cutting' meths with water. The idea being that it might help your fuel go further and I believed it might also offer a certain degree of control over how 'fierce' a stove burns. Anyway, you can see from the pictures what happens as you increase the percentage of water.


Straight meths


10% water


20% water


40% water ... not too keen on lighting I have to say

[Ian]

GCSE Science taught me that blue flames are hotter than yellow ones, so I figure that the 40% water is burning hotter? So, can you please explain why you get a hotter flame by adding water :?

[chris n]

It's a good idea to dilute it a bit anyway. Pure meths leaves soot on your pans - adding 5 to 10% water prevents this.

[Ian]

Sorry, I'm being thick. I now understand your last comment

[Bearbonesnorm]

The hottest part of the flame is the point where a blue flame just starts to turn yellow. What the pics really show is the relationship between air/fuel, a yellow flame indicates that there's more fuel available than can be burnt. By adding water you're just reducing the amount of fuel available.

The stove in the pics is free to vent to atmosphere, if you place a mug on the stove and allow it to work as intended things change quite a bit. When burning straight meths the flames will settle down to almost pure blue within a second or so. If you do the same on the 20% water mix, the flames become quite a pale blue and reduce in size by about half. Try it with 40% water and the flames turn almost white and after a few seconds the stove will go out as it now becomes starved of fuel.

Obviously the added water also has a dramatic effect on the size of the flames too.