Accessory Equipment For Surfacesupplied Diving

Accessory equipment that is often useful in surface-supplied diving operations includes the following items:

■ Lead Line. The lead line is used to measure depth.

Descent Line. The descent line guides the diver to the bottom and is used to pass tools and equipment. A 3-inch double-braid line is recommended, to prevent twisting and to facilitate easy identification by the diver on the bottom. In

Air Consumption


Minimum Manifold Pressure (MMP)

Average Over Period of Dive (acfm)

MK 21 MOD 1

(Depth in fsw x 0.445) + 90 to 165 psi, depending on the depth of the dive

1.4 (Note 1)

MK 20 MOD 0

(Depth in fsw x 0.445) + 90 psi


Note 1:The manifold supply pressure requirement is 90 psig over-bottom pressure for depths to 60 fsw, and 135 psig over-bottom pressure for depths from 60-130 fsw. For dives from 131-190 fsw, 165 psi over-bottom pressure shall be used.

■ Cooling. Cooling the air prior to expanding it raises its relative humidity, permitting some of the water to condense. The condensed liquid may then be drained from the system.

8-6.1.5 Standby Diver Air Requirements. Air supply requirements cannot be based solely on the calculated continuing needs of the divers who are initially engaged in the operation. There must be an adequate reserve to support a standby diver should one be needed.

8-6.2 Primary and Secondary Air Supply. All surface-supplied diving systems must include a primary and a secondary air supply in accordance with the U.S. Navy Diving and Manned Hyperbaric Systems Safety Certification Manual, SS521-AA-MAN-010. The primary supply must be able to support the air flow and pressure requirements for the diving equipment designated (Table 8-1). The capacity of the primary supply must meet the consumption rate of the designated number of divers for the full duration of the dive (bottom time plus decompression time). The maximum depth of the dive, the number of divers, and the equipment to be used must be taken into account when sizing the supply. The secondary supply must be sized to be able to support recovery of all divers using the equipment and dive profile of the primary supply if the primary supply sustains a casualty at the worst-case time (for example, immediately prior to completion of planned bottom time of maximum dive depth, when decompression obligation is greatest). Primary and secondary supplies may be either high-pressure (HP) bank-supplied or compressor-supplied.

8-6.2.1 Requirements for Operating Procedures and Emergency Procedures. Operating procedures (OPs) and emergency procedures (EPs) must be available to support operation of the system and recovery from emergency situations. OPs and EPs are required to be NAVSEA or NAVFAC approved in accordance with paragraph 4-2.6.3. Should the surface-supplied diving system be integrated with a recompression chamber, an air supply allowance for chamber requirements (Volume 5) must be made.

All valves and electrical switches that directly influence the air supply shall be labeled:

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