Chapter 48 

 CARBON MONOXIDE IN THE ATMOSPHERE OF SEALAB II 



Merle E. Umstead, 

 Naval Research Laboratory 

 Washington, D. C. 



During the latter part of the Sealab II operation, the occupants of Sealab frequently com- 

 plained of headaches. The presence of carbon monoxide in the atmosphere was suspected as a 

 possible cause, and tests were carried out for its detection. 



Carbon monoxide measurement by means of detector tubes inside Sealab indicated the pre- 

 sence of about 150 ppm of CO. Similar detector-tube measurements on the surface with air 

 from the sampling line from Sealab showed about 25 ppm. This difference is to be expected, 

 since in using detector tubes, a fixed volume of air is drawn through the tube and a color 

 change measured. In Sealab, at seven atmospheres pressure, the sample at STP would contain 

 seven times as much gas as that used in a similar test carried out on the surface at atmos- 

 pheric pressure. In addition to these tests, a compressed sample of Sealab air was taken on 

 Sept. 28 and sent to the Linde Company for analysis. A value of 25 ppm CO was reported. 



In an attempt to remove the CO from the Sealab atmosphere, four of the lithium hydroxide 

 canisters in the CO removal system were partially filled with Hopcalite, a catalyst used a- 

 board nuclear submarines for the oxidation of CO. Later, silica gel was placed in the air 

 stream ahead of the Hopcalite, since it was known that Hopcalite is an effective catalyst for CO 

 removal at room temperature when dry, but is not so effective when wet. 



At this time, a Beckman GC-2A Gas Chromatograph that was being used aboard the sup- 

 port vessel for trace organic contaminant analysis was equipped with a molecular sieve col- 

 umn to attempt to monitor the CO concentration in Sealab. By taking a massive air sample 

 and pushing the detector sensitivity to its limit, CO could be estimated reasonably well. The 

 full capability of the instrument was impaired, because the chromatograph 's hot-wire detector 

 was sensitive to the wave motion of the vessel. However, it was possible to follow the CO con- 

 centration, and it was found that from the time of the installation of the Hopcalite and the 

 chromatographic monitoring, the CO level in Sealab diminished gradually until the end of the 

 operation. 



Samples of Sealab air were taken daily by means of stainless steel gas bottles for trace 

 organic contaminant analysis. The evacuated bottles were sent down to Sealab and filled to 

 ambient pressure. Thus, when the bottles were returned to the surface, they were under a 

 positive pressure of about six atmospheres. A number of these samples were retained for 

 later, more detailed analysis at NRL including identification of the individual contaminants. 

 The bottles saved were spaced over a large protion of the Sealab operation. These samples 

 were analyzed at the Laboratory for CO by means of a gas chromatograph equipped with a 

 Karmen electrical-breakdown detector (1,2) which provides high sensitivity for gases such as 

 CO. 



The bottle samples provided sufficient data to obtain a profile of the CO levels over most 

 of the Sealab II operation. The data are plotted in Fig. 169. This figure shows that during the 

 first few weeks, the CO concentration rose linearly at a rate of 1.57 ppm per day. Based upon 

 a free volume of 4500 cu ft, and a pressure of 7 atm, this rate corresponds to the liberation of 

 1.4 liters (STP) of pure CO per day to the Sealab atmosphere. During the latter few weeks of 

 the operation, the CO concentration gradually decreased. Unfortunately, no samples were 

 available for the intermediate period. As may be seen from the extrapolated line in Fig. 169, 



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