taken from Appendix 16 of reference (6); it is 

 only changed insofar as references and table 

 numbers are concerned to make them com- 

 patible with the numbering herein: 



^^Review of life support systems indi- 

 cates wide variance in certification 

 standards with reference to the time 

 requirements. 



An extensive survey (G. E., NRL, 

 Westinghouse, I\avy Sup-Dive, etc.) 

 also indicates that basic performance 

 data are not available for all condi- 

 tions — particularly conditions of low 

 temperature and high pressure. Test 

 programs have been proposed by NRL 

 to accomplish this ivork but the pro- 

 grams have never been funded. Basic 

 characteristics of the commonly used 

 materials are shown in Table 9.5 

 (taken from ref. 6). It can be inferred 

 from ref. (8) that LiOH performance 

 would have been operating in a near 

 optimum condition at the loiv temper- 

 atures encountered, and that it has a 

 relatively flat performance curiae in 

 terms of temperature variation. It 

 should be noted, however, that the 



actual tests (8) did not use gas input 

 temperatures below 77°F. 



It is significant that the most de- 

 tailed investigations have been per- 

 formed in connection with develop- 

 ment of closed circuit breathing rigs. 

 These investigations have universally 

 noted sensitivity of the removal proc- 

 ess to temperature, to moisture, to the 

 precision of packing the cannisters 

 and to the configuration of the cannis- 

 ters. Effectiveness of removal is en- 

 hanced in the closed circuit design by 

 the diver breathing warm air directly 

 into the cannister, a process which is 

 not used in submersibles. They have 

 also noted marked deterioration, ptir- 

 ticularly in low temperature perfor- 

 mance, which appears to be the result 

 of water condensing in the cannister, 

 as well as possible temperature varh- 

 ance in the rate of reaction. 



Serious deterioration in perfor- 

 mance was noted for baralyme stored 

 in standard waxed containers. These 

 conditioners are intended for use in 

 hospitals where storage conditions are 

 controlled and 2-year life is expected. 



TABLE 9.5 CHARACTERISTICS OF THREE CARBON DIOXIDE ABSORBENTS [FROM REF. (6)] 



Characteristic 



Baralyme 



Absorbent 



Lithium hydroxide 



Soda Sorb 



Absorbent density, Ib/ff' 65.4 



Theoretical CO2 absorption, lb C02/lb 0.39 



Theor. water generated, lb/lb CO^ 0.41 



Theor. heat of absorption, Btu/lb CO2 67o'' 



Useful CO2 absorption, lb C02/lb (based on 50 percent efficiency) 0.195 



Absorbent weight, lb per diver hr (0.71 lb CO2) 3.65 



Absorbent volume, ft per diver hour 0.0558 



Relative cost, S/diver hr (1968) $1.75 



Based on generating gaseous H^O 



Based on calcium hydroxide reaction only 



55.4 



0.49 



0.41 

 670^ 



0.245 



2.90 



0.0533 

 $0.75 



421 



