Heat loss and tolerance time during cold exposure in heliox atmosphere at 16 ATA.

Four different types of protective clothing and three different methods of heat conservation protection were evaluated during an exposure to 4 degrees C cold in a heliox atmosphere at 150 msw. The divers using protective systems with little insulation had to quit the test after 1-2 h due to uncontrollable shivering and an extreme feeling of cold, whereas the divers using the heavily insulated clothing were able to stay in the chamber for 8-10 h. However, even with adequate protection against convective heat loss from the skin, respiratory convective heat loss will be high unless inspired gas is heated. This can be adequately done by using a combined heat-exchanger and scrubber where the heat produced by CO2 absorption is used to warm the inspired gas.