I built a Water Bellows. It’s an upside-down clay pot with an inlet valve and an outlet spout. The inlet valve is simply a hole in the pot with a leaf plastered to the inside with wet clay so that it forms a one-way flap valve. When pushed down into water, the valve shuts and air is forced out of the spout and into the fire. When the pot is lifted in water, air is sucked in through the open inlet valve and the cycle repeats. I got the idea from a Food and Agriculture Organization website I saw years ago. A Google image search for “FAO water bellows” gives an image of someone using a more complicated version at a brick forge in Zimbabwe, possibly from 1994, but I can no longer find the original diagram or description.
source.image: Primitive Technology
From memory, the air and water containers were steel drums and there was a U-shaped pipe to convey the air down from inside the air drum when lowered, through and out the water drum and into the fire. Air entered an inlet valve in the top of the air drum when lifted. There may also have been an outlet valve which would presumably have been located on the outlet pipe. The pipe remained stationary through the cycle.
My design is a simplified version of this with a spout leading directly from the air pot into the fire. The spout moves with the pot instead of being fixed in place as it is raised and lowered. The spout nose is resting in place on the ground in front of the fire acting as a hinge, with the whole unit acting as a lever. If the nose of the spout is resting in the entrance of a fixed tuyere (air pipe) then the angle of the jet can be kept constant with the added advantage of the venturi effect drawing in more air. My design also only has one valve (inlet) for simplicity.
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The bellows produced a similar effect to the traditional blacksmith bellows without requiring leather to build. It seems to produce a higher-pressure jet of air than the blower I’ve used previously. It’s also less complicated to build, with fewer perishable materials and has fewer moving parts that often break or seize during use..Primitive Technology
