Figure 1.

A typical saturation worksite. The divers are deployed from the diving support vessel inside a diving bell. Once on site, the bell’s door opens, and the divers lock out in the water using an umbilical attached to the bell to breathe and being supplied with hot water in their suit for thermal comfort. The working depth corresponds to the maximum depth reached by the divers. The working depth defines the chamber storage depth from excursion tables prepared in the company diving manual. The bell depth is usually set at 5 msw deeper than the storage depth to clear from subsea structures when opened. The “storage” and the “bell” are almost at the same pressure allowing for getting back to storage after work without decompression needed. The excursion of the diver out of the diving bell is limited to some meters not to add additional decompression time. The breathing gas is Heliox (Helium-Oxygen) to limit the density of the breathed gas (significant at such pressures) to reduce the work of breathing as well as Oxygen toxicity and Nitrogen narcosis.