INJECTION AND TESTING

When everything was assembed, there was an extra barb left open at the top of the extraction chamber. This is where you will inject butane. You need to figure out some way of getting the butane in. This means a means of depressing the valve of the butane can while it is inserted into the barb. I used a piece of rubber hose, inset into the barb such that the valve of the butane can was pressed as the can was touching the rim of the barb. This sealed the backflow of butane as it entered the system. Since valves differ on different butane products, you'll have to wing this part.

The other part of the injection issue is plugging the hole you just filled from. A piece of the re-enforced hose with an empty (fired) .38 cartridge makes a good plug -- remember the hose clamps!

Once you think you have an innjector valve built, hang the entire business up at a comfortable height. It will hang from the bail on the bucket just fine.

Testing and operation with butane is best done on a cold day. Cold means below freezing. Butane boils at about 30f (-0.5c). We don't want it to boil anywhere but in the expansion chamber.

To keep things below boiling, and to condense vapors, we need to cool the butane. This is what the coil is used for. To cool the coil, take a gallon jug of ice that has been frozen in the deep freeze. Peel off the container so you just have the ice. Slip the ice into the middle of the coil. If you can fit two gallons, do it.

I next use snow to pack around the ice. When that's a full as I can get it, I grab a gallon of heavily salted water that has also been in the deep freeze till little bits of ice are forming. This is about +20f. Pour this water into the bucket. Put a thermometer in it till it's all below 25f in there. Save about 2 cups of the water.

Get a platform up to within a couple inches of the bottom of the expansion chamber. suspend the chamber in a mixing bowl and add the two cups of icy water to the bowl. When everything is down to 25f or lower, you're ready to test the unit.