424 



CARBON MONOXIDE IN ATMOSPHERE 



80 



27 31 



AUGUST 



12 16 20 



SEPTEMBER 



Fig. 169. Carbon monoxide concentration in Sealab II 



if CO had continued to build up at the initial rate , the concentration in Sealab would have 

 reached 70 ppm by the end of the operation. 



It was very surprising to find that the CO concentration in Sealab had been decreasing for 

 several days prior to placing Hopcalite in the system. Also, there was no noticeable change 

 in the slope of the curve after the Hopcalite was in place. This result raises doubts as to 

 whether the Hopcalite was at all effective in removing CO under the conditions in which it was 

 used. It is possible that CO was generated through some process, such as cooking, which was 

 stopped when CO was suspected of being a problem. After this, the CO was removed gradually 

 by some still unknown mechanism. 



It should be emphasized that the CO values reported in Fig. 169 are expressed in parts per 

 million, as is commonly done when considering samples at atmospheric pressure. However, 

 Sealab II was at 7 atm pressure, and the effects of CO at high pressures are not known. If the 

 physiological effects of CO are dependent upon its partial pressure, as is true for oxygen and 

 carbon dioxide, then the physiologically effective concentration of CO in Sealab would corres- 

 pond to seven times the values given in Fig. 169. 



Based on the results found to date, it is recommended that: 



1. Investigations be made of possible sources of CO in an enviroment such as Sealab. 



2. 

 Sealab, 



An accurate and sensitive method of monitoring CO be developed for use for future 



3. Equiprnent be developed for removing CO from atmospheres under high pressures and 

 humidity andalow percentage of oxygen, based upon catalytic oxidation or some other principle. 



4. Attention be given to studying the physiological effects of CO at high pressures. 



