| タイトル | Effects of Material Choice on Biocide Loss in Orion Water Storage Tanks |
| 本文（外部サイト） | http://hdl.handle.net/2060/20160005443 |
| 著者（英） | Wallace, William T.; Hudson, Edgar; Gazda, Daniel B.; Lewis, John F.; Kuo, C. K. Mike; Castro-Wallace, Sarah L.; Loh, Leslie J. |
| 著者所属（英） | NASA Johnson Space Center |
| 発行日 | 2016-07-10 |
| 言語 | eng |
| 内容記述 | When preparing for long-duration spaceflight missions, maintaining a safe supply of potable water is of the utmost importance. A major risk factor, potentially jeopardizing the safety of the water supply, is the presense of microorganisms. Historically, the challenge of controlling microbial proliferation has been addressed through the maintenance of residual biocide levels. While chemical biocides are effective, their use requires carefeul consideration towards materials selection for the water storage containers, as surface reactions can reduce biocide concentrations below their effective range. In the water storage system baselined for the Orion vehicle, the primary wetted materials are passivated stainless steel (316 L) and a titanium alloy (Ti6Al4V). Previous testing with these materials has shown that the biocide selected for use in the system, ionic silver, will plate out rapidly upon initial wetting. One potential approach for maintaining an adequate biocide concentration is to spike the water supply with high levels of biocide in an attempt to passivate the surface. To evaluate this hypothesis, samples of the wetted materials were tested individually and together to determine the relative loss of biocide under representative surface area-to-volume ratios after 24 hours. Additionally, we have analyzed the efficacy of disinfecting a system containing these materials by measuring reductions in bacterial counts in the same test conditions. Preliminary results indicate that the use of titanium alloy, either individually or in combination with stainless steel, can result in over 95% loss of biocide, while less than 5% is lost when using stainless steel. In bacterial testing, viable organisms were recovered from samples exposed to the titanium coupons after 24 hours. By comparison, no organisms were recovered from the test vessels containing only stainless steel. These results indicate that titanium alloys, while possessing some favorable attributes, may pose additional challenges when used in water storage tanks with ionic silver biocide. |
| NASA分類 | Man/System Technology and Life Support |
| レポートNO | ICES-2016-313
JSC-CN-36156 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/561993 |
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