cated at a distance from the hull or other 

 critical pressure-resistant components such 

 that the flask's implosion will not damage 

 other items. (See Chap. 13 for "stand-off dis- 

 tance.") 



There are ABS regulations on the storage 

 flasks themselves: Storage pressure of 5,000 

 psi cannot be exceeded; the containers must 

 comply with Department of Transportation 

 (DOT) specifications (Part 78, Sub-part C; 

 Sects. 78.36 to 78.68 inclusive) or any recog- 

 nized standards; and on small cubmersibles 

 (less than 60 meters LOA) the containers 

 must be proof-tested and marked in accord- 

 ance with DOT procedures approximately 

 once every year, but not exceeding 18 

 months. 



It is not the intent of this discussion to 

 recommend what life support systems should 

 be, but merely to relate what they are. The 

 reader should be aware, however, that both 

 the Navy and ABS quite explicitly state cer- 

 tain material requirements for: Piping, fit- 

 tings and valves; operating pressures for 

 control and monitoring devices; cleaning and 

 storing; and testing and maintenance of the 

 entire system. 



Control of the flow of oxygen into the pres- 

 sure hull is approached in three ways: The 

 simplest is by periodically opening the flow 

 valves; the most common is by continually 

 bleeding the oxygen through a flow control 

 valve and flow indicator; and the least com- 

 mon is by automatically admitting oxygen by 



FLOW CONTROL 

 VALVE 



CYLINDER VALVES 



SHUT-OFF 

 VALVE 



PRESSURE 

 RELIEF 

 VALVE 



FILLING 



SHUT-OFF 



VALVE 



STORAGE 



PRESSURE 



GAGE 



SHUT-OFF 

 VALVE 



FILLING CONNECTION 



BLOWER 



AIR MIXING 

 DUCT 



DIFFUSER 



FOR 



DEFOGGING 



VIEWPORT 



FLOW 

 NDICATOR 



PRESSURE 

 REGULATOR 



Fig. 9.2 Oxygen supply system schematic. [From Ref. (10)1 

 414 



