Coolgardie safe

Coolgardie Safe at Kalgoorlie's Mining Museum, part of the Western Australian Museum.

The Coolgardie Safe is a low-tech refrigeration unit which uses the heat transfer which occurs during evaporation of water. It was named after the place where it was invented — the small mining town of Coolgardie, Western Australia, near Kalgoorlie-Boulder.

History

Coolgardie was the site of a gold rush in the early 1890s, prior to the Kalgoorlie-Boulder gold rush.

For the white prospectors who had rushed here to find their fortune, the harsh desert climate created great challenges. One such challenge was to extend the life of their perishable foods — hence the invention of the Coolgardie safe.

The safe was invented in the late 1890s. It is uncertain who invented it, but it clearly uses the same principle as explorers and travellers in the Outback used to cool their canvas water bags. When the canvas bag is wet the fibres expand and it holds water. Some water seeps out and evaporates, especially if it is in a breeze, and this keeps the stored water cool.

This technology in turn is commonly thought to have been adopted by explorer and scientist Sir Thomas Livingstone Mitchell, who had observed the way some Aborigines used kangaroo skins to carry water.

Principles of operation

The Coolgardie Safe was made of wire mesh, hessian, a wooden frame and had a galvanised iron tray on top. The galvanised iron tray was filled with water. The hessian bag was hung over the side with one of the ends in the tray to soak up the water.

Gradually the hessian bag would get wet. When a breeze came it would go through the wet bag and evaporate the water. This would cool the air and in turn cool the food stored in the safe.

It was usually placed on a veranda where there was a breeze. The Coolgardie safe was a common household item in Australia up to the mid-twentieth century. Safes could be purchased ready-made or fairly easily constructed at home. Some of the metal panel safes are very highly decorated, showing the great creativity of their makers.

References

[Category:http:// Australian inventions http://www.datamediasafes.com]