DECOMPRESSION COMPLEX 



119 



Fig. 60. Deck decompression chamber 



PTC-DDC OPERATIONS 



In normal operations, with the PTC on the sea bottom, the saturated divers enter and close 

 the hatch in the bottom of the capsule, thereby sealing themselves at bottom pressure. The 

 PTC is then hoisted aboard the support vessel and set on deck. The chamber is removed from 

 the stand and base (Fig. 55) and placed on the mating hatch of the DDC (Figs. 56 and 57). The 

 PTC is sealed to the DDC by means of a "tube turn" clamping ring (Fig. 59). The pressures in 

 the PTC and DDC are equalized, and the hatches of the PTC and DDC are then opened. The 

 divers then enter the DDC from the PTC, close the DDC hatch, and undergo decompression. 

 The PTC is then returned to the ocean floor as the emergency capsule for the next team. 



CHRONOLOGY 



Functional specifications for development of the PTC and DDC were given to bidders on 

 Feb. 10, 1965. Dixie Manufacturing Company of Baltimore, Maryland, was selected by a re- 

 view board on Mar. 1 to be awarded the design and fabrication contract. After notification of 

 contract award on Mar. 10, Dixie immediately initiated detailed design engineering and pro- 

 curement of steel and major components for fabrication. 



The steel industries of the United States were threatened with a strike shortly after the 

 acceptance of Dixie's proposal. This threat resulted in delay in delivery of the steel for both 

 the DDC and PTC. Steel was finally delivered during the last week of May. 



Several other components caused delay to the completion of the chambers. These were: 

 oxygen reducing valve for inside the PTC, the medical lock for the DDC, the forged door rings 

 for the DDC, and the counterbalance springs for the overhead hatch in the DDC. A number of 

 modifications instituted in the basic design from mid-March through delivery by Dixie were 

 followed by additional modifications at the Long Beach Naval Shipyard. 



A certification board, headed by Captain L. B. Melson of the Office of Naval Research, 

 was appointed by the Chief of Naval Research to review the design and make recommendations 

 to insure that the design met safety requirements. This board inspected the PTC and DDC at 

 Dixie on July 15. Recommendations of the Board were received on July 23. 



