ENGINEERING EVALUATION 323 



Arawak System 



The Arawak system was utilized to pump the Sealab atmosphere to a swimmer through a 

 hose. As the swimmer exhales, the gas is returned through a second hose to the Sealab II at- 

 mosphere for reprocessing. The equipment installed in the Sealab consisted of two positive- 

 displacement, carbon-vane pumps driven by separate one-horsepower electric motors. One 

 pump, operating at approximately 23 psig, supplied breathing gas to one swimmer while the 

 other pump, operating at a negative pressure of approximately 15 in. Hg, returned the exhaled 

 gases to the Sealab. This equipment was mounted overhead in the entry area. Two complete 

 systems were installed, with cross connections to provide continuing operation in the event of 

 failure of either system. 



Plumbing and Sanitary System 



The plumbing and sanitary systems were essentially of conventional design. The plumbing 

 system was designed to operate at a pressure of approximately 40 psi over ambient, with 

 pressure-relief valves set at 100 psi over ambient. All fixtures were conventional; the water 

 closet was a marine type utilizing sea water for flushing. The sanitary system was a gravity- 

 flow system, with direct overboard discharge. The discharge openings were kept below the 

 water level in the entry trunk in order to prevent atmosphere loss. All fixtures were trapped. 

 Sanitary lines were vented inside the habitat into the charcoal filter of the ventilation system 

 to eliminate odors. The water closet was connected to one sanitary drain and all other fixtures 

 (lavatory, two sinks, and two showers) to the second drain. Flexible hoses 50 ft long were at- 

 tached to the sanitary discharge openings to carry the effluent away from Sealab II. Water was 

 supplied from shore through two 3/4-in. plastic (PVC) pipes approximately 3,500 ft long. Shore 

 water pressure could be varied from approximately 70 to 100 psi and was metered to determine 

 usage rates. An emergency fresh-water tank of 150-gallon capacity was provided in the event 

 of interruption of the shore supply. This tank was not pressurized and was not connected to 

 the normal water system. 



Communication System 



Communication between Sealab II and the Command Control Center on the support vessel 

 was provided by a communication cable in the umbilical cord. The cable terminated in patch 

 panels in the habitation space and in the Command Control Center. Receptacles were utilized 

 in the patch panels to facilitate connecting the various pieces of equipment at the test site. The 

 following modes of communication and instrumentation were provided: 



1. Helium Speech Unscrambler - three circuits 



2. Electrowriter, two-way 



3. Television - closed circuit monitoring 



4. Television - aquanauts' entertainment 



5. Audio - intercom, two-way 



6. Audio - carrier-transmitted two-way voice communication between support vessel and 

 shore (via Sealab and benthic lab) 



7. FM music - aquanauts' entertainment 



8. Wedge spirometer output 



9. Oxygen partial pressure 

 10. Open microphones. 



The patch panel in Sealab 11 was located in an area on the port side of the laboratory des- 

 ignated the communication and watch center. All communication with surface control originated 

 at this point, except two helium speech unscrambler circuits, which were installed in the galley 

 and berthing area. The primary purpose of the two additional helium speech unscrambler 



