Dive_Man_ChangeA

13-8 Change A U.S. Navy Diving Manual—Volume 3 mixed gas diving is that there be adequate quantities of the appropriate gases on hand, as well as a substantial reserve, for all phases of the operation. The initial determinations become critical if the nearest point of resupply is far removed from the operation site. 13-3.10.1 Gas Consumption Rates. The gas consumption rates and carbon dioxide absor- bent durations for various types of underwater breathing apparatus are shown in Table 13-1. Refer to Chapter 4 for required purity standards. 13-3.10.2 Surface Supplied Diving Requirements. For surface supplied diving, the diver gas supply system is designed so that helium-oxygen, oxygen, or air can be supplied to the divers as required. All surface supplied mixed gas diving systems require a primary and secondary source of breathing medium consisting of helium-oxygen and oxygen in cylinder banks and an emergency supply of air from compressors or high-pressure flasks. Each system must be able to support the gas flow and pressure requirements of the specified equipment. The gas capacity of the primary system must meet the consumption rate of the designated number of divers for the duration of the dive. The secondary system must be able to support recovery operations of all divers and equipment if the primary system fails. This may occur immediately prior to completing the planned bottom time at maximum depth when decompression obligations are the greatest. Emergency air supply is provided in the event all mixed gas supplies are lost. 13-3.10.3 Deep Diving System Requirements. A deep diving system must be able to store and supply enough gas to support saturation diving to the maximum certified depth. Deep diving systems can handle and store pure gases, and mix the required percentages of helium-oxygen as needed. When DDS type equipment is employed, additional quantities of gas must be included for DDC and PTC charging and for replacing losses due to leakage, transfer trunk and service lock usage and scrubber cycling. A DDS must also have an air system capable of supporting surface supplied air diving operations and initial pressurization of the DDS for saturation operations. 13-4 SELECTING AND ASSEMBLING THE DIVE TEAM Selecting a properly trained team for a particular diving mission is critical. Refer to Chapter 6 for an expanded discussion on dive team selection, as well as the criteria for selecting qualified personnel for various tasks. It is critical to ensure that only formally qualified personnel are assigned. The Diving Officer, Master Diver, and Diving Supervisor must verify the qualification level of each team member. The size and complexity of deep dive systems reinforces the need for a detailed and comprehensive watch station qualification program. 13-4.1 Diver Training. Training must be given the highest command priority. The command that dives infrequently, or with insufficient training and few work-up dives between operations, will be ill prepared in the event of an emergency. The dive team must be exercised on a regular diving schedule using both routine and nonroutine drills to remain proficient not only in the water but on topside support