320 



ENGINEERING EVALUATION 



Breathing-Gas Systems 



General — The primary breathing (atmosphere) gases for Sealab n were stored externally 

 in 24 standard 1300-cubic-foot bottles at a nominal pressure of 2400 psig. All high-pressure 

 lines were designed for 3000-psi service, and all low-pressure lines for 400 psi. A gas- 

 control panel was installed above the communication center on the port side of the lab area to 

 provide centralized control and monitoring of all gas systems, with the exception of the emer- 

 gency breathing (Bibb) system. The Bibb system controls were located in the galley area for 

 utmost convenience in the available space. All pressure regulators were of the standard weld- 

 ing type, which were easy to obtain and which permitted easy adjustment at ambient pressure. 

 Three identical regulators were used. They were interchangeable and required a minimum 

 stock of spare parts. 



Oxygen System —An on-board oxygen supply of 14,300 cu ft was provided as the primary 

 breathing supply. The oxygen system was installed essentially as shown in Fig. 126. The pri- 

 mary oxygen system was automatic in operation and was controlled by the Krasberg oxygen 

 partial-pressure sensor. This unit monitored oxygen partial pressure and in turn controlled 

 an electrically operated solenoid valve to admit oxygen as needed. Remote readouts were pro- 

 vided on the surface vessel for topside monitoring. Two separate, manually selected supplies 

 of oxygen were available. 



SCRUBBER FILTER 

 EXHAUST PLENUM s." 



POa SENSOR aT 

 (115 VAX.) . ■ 



AUTOMATIC 02 MAKE -UP 



MANUAL 02 MAKE-UP 



MANUAL 02 MEASUREMENT 

 2-200 CU. FT BOTTLES 



;l_ 



SERVO VALVE 



DISTRIBUTION 

 DUCT 



GAS FLOW 



NOTE: 



GAS SAMPLING 



LINE TO BE 



UPSTREAM 



OF 02 MAKE-UP 



^ GAS CONTROL 

 PANEL 



-STUFFING TUBE 





tlZX?^ 



-HULL (BOTTOM) 

 ' 02 STORAGE, EXTERNAL, 11-1300 CU.FT 

 BOTTLES ON TWO MANIFOLDS 



yy^ln^ 



Fig. 1Z6. Sealab II oxygen system 



A secondary, manually operated system was included as a backup in the event of failure of 

 the automatic system. 



The primary input of oxygen was directed into the discharge of the ventilation system to 

 provide thorough mixing. This point of introduction also prevented high oxygen concentrations 

 in the immediate vicinity of the blower motor. An input directly into the atmosphere was pro- 

 vided for use in the event of failure of the blower system. 



A third oxygen-supply system was tied into the manual oxygen system so that emergency 

 oxygen could be supplied from the surface. This supply would utilize the gas-sampling system 

 via the umbilical cord. 



