Saturation diving

Saturation diving is an ambient pressure diving technique which allows a diver to remain at working depth for extended periods during which the body tissues become saturated with metabolically inert gas from the breathing gas mixture. Once saturated, the time required for decompression to surface pressure will not increase with longer exposure. The diver undergoes a single decompression to surface pressure at the end of the exposure of several days to weeks duration. The ratio of productive working time at depth to unproductive decompression time is thereby increased, and the health risk to the diver incurred by decompression is minimised. Unlike other ambient pressure diving, the saturation diver is only exposed to external ambient pressure while at diving depth. The extreme exposures common in saturation diving make the physiological effects of ambient pressure diving more pronounced, and they tend to have more significant effects on the divers' safety, health, and general well-being. Several short and long term physiological effects of ambient pressure diving must be managed, including decompression stress, high pressure nervous syndrome (HPNS), compression arthralgia, dysbaric osteonecrosis, oxygen toxicity, inert gas narcosis, high work of breathing, and disruption of thermal balance. Most saturation diving procedures are common to all surface-supplied diving, but there are some which are specific to the use of a closed bell, the restrictions of excursion limits, and the use of saturation decompression. Surface saturation systems transport the divers to the worksite in a closed bell, use surface-supplied diving equipment, and are usually installed on an offshore platform or dynamically positioned diving support vessel. Divers operating from underwater habitats may use surface-supplied equipment from the habitat or scuba equipment, and access the water through a wet porch, but will usually have to surface in a closed bell, unless the habitat includes a decompression chamber. The life...