Rocket stove upgrade-part two

The benefit of a disaster

We had promised to provide cooking facilities for a few  families at a school camp-out. We unloaded the gas cylinder, added the “skottel* , lit it and “whoosh “, the entire setup was engulfed in pale blue flame! Quite an exciting start to the planned meal!

Fortunately we were able to deal with the flames quickly. We thought we were going to go hungry but a friendly parent and fellow camper loaned us a newer , more modern set up and dinner was soon served. We decided we would never take a chance with that gas cylinder again and it was committed to the junk pile.

* A “skottel” is a plough share that is cleaned up and traditionally used for cooking on an open fire in South Africa. Over time, a commercialised, gas heated version has appeared.

The original rocket stove’s burn chamber was too small and the lure of a scrapped gas bottle proved to be too much temptation. This was the trigger that started the rocket stove upgrade part two.

Starting the build

Step one was to ensure that as much gas had been purged from the cylinder as possible. We removed the brass sealing screw and left it outside for a couple of months. The next step was to fill it with water. This was a slow process but using a small funnel we got it right eventually.

A scrapped, old, leaking gas cylinder to be used as a burn chamber in the rocket stove upgrade part two
A scrapped old leaking gas cylinder

Once full we let it stand for a further week. Using a large angle grinder while the gas cylinder was still full of water we cut around the central seam.

Cutting the scrapped water filled gas cylinder along the centre seam to create the burn chamber for the rocket stove upgrade part two
Scrapped water filled gas cylinder cut at central seam
The two halves of the scrapped gas cylinder. Please note that it was full of water when cut. These are the top and bottom of the burn chamber used in the rocket stove upgrade part two
Two halves of the scrapped gas cylinder

Water went everywhere but fortunately this was done outdoors so that did not matter.  Then using a smaller grinder we removed the rusted handle and cut a square opening for the chimney. 

To show how the chimney slot removed the brass fittings and rusted handle
Initial cutting of gas cylinder completed

We then took the bottom half and drilled the hole for the air feed using a  hole saw which allowed a nice snug fit for the pipe we had selected. To remove the “spout” that led down from hole to the left of the square in the picture above, was quite tricky because of the shape of the half cylinder. Once cut it was ground flat. A suitable piece of square tubing was cut to length for the chimney and tack welded to the top half. We already had a surplus plough share and decided that using it would allow a greater cooking surface. More detail of the build will explanation in the next post .

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