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Written by Garry K. Smith.Abstract: The paper examines the reliability of the "Naked Flame Test" for measuring the concentration of carbon dioxide (CO2) in caves. It reviews the ways in which carbon dioxide gets into caves, how it forms pockets of high concentration and the composition of the atmospheres in these pockets. A cave air index is used to generate theoretical tables of cave atmospheres compositions for two scenarios composed of carbon dioxide from different sources. Conditions for combustion together with levels of carbon dioxide and oxygen (O2) required to extinguish flames are stated. The fuel components of various combustible materials available for the Naked Flame Test are described. The paper presents and discusses the results of the laboratory tests on matches, candles and butane cigarette lighter in reduced oxygen atmospheres. It reviews the physiological effects of low O2 and high CO2. It is concluded that the Naked Flame Test measures O2 concentrations and is unreliable for measuring CO2 concentrations. Elevated CO2 levels are recognised as being the life threatening component of most cave atmospheres, however, it is also concluded that the Naked Flame Test is still the safest way for an inexperienced caver to test for hazardous cave atmospheres. Open Access See Extended description for more information.
"Naked Flame Tests for, and Human Tolerance to, Foul Air in Caves." (1996). KIP Articles. 3433.