Record Details

Process Development for Removal of Siloxanes from ISS Atmosphere
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Author and Affiliation:
Carter, Layne(NASA Marshall Space Flight Center, Huntsville, AL, United States);
Perry, Jay(NASA Marshall Space Flight Center, Huntsville, AL, United States);
Kayatin, Matthew J.(NASA Marshall Space Flight Center, Huntsville, AL, United States);
Wilson, Mark(Boeing Co., Houston, TX, United States);
Gentry, Gregory J.(Boeing Co., Houston, TX, United States);
Bowman, Elizabeth(Boeing Research and Technology, Huntsville, AL, United States);
Monje, Oscar(NASA Kennedy Space Center, Cocoa Beach, FL, United States);
Rector, Tony(United Technologies Corp., Windsor Locks, CT, United States);
Steele, John(United Technologies Corp., Windsor Locks, CT, United States)
Abstract: Dimethylsilanediol (DMSD) has been identified as a problematic organic contaminant aboard the ISS. This contaminant was initially identified in humidity condensate and in the Water Processor Assembly (WPA) product water in 2010 when routine water quality monitoring an increasing total organic carbon (TOC) trend in the WPA product water. Although DMSD is not a crew health hazard at the levels observed in the product water, it can degrade the WPA catalytic reactor's effectiveness and cause early replacement of Multifiltration Beds. DMSD may also degrade the performance of the Oxygen Generation System (OGS) which uses the WPA product water for electrolysis. An investigation into the source of DMSD has determined that polydimethylsiloxane (PDMS) compounds are likely hydrolyzing in the Condensing Heat Exchangers (CHX) to form DMSD. PDMS compounds are prevalent aboard ISS from a variety of sources, including crew hygiene products, adhesives, caulks, lubricants, and various nonmetallic materials. PDMS compounds are also known to contribute to CHX hydrophilic coating degradation by rendering it hydrophobic and therefore adversely affecting its ability to effectively transmit water to the condensate bus. Eventually this loss in performance results in water droplets in the air flow exiting the CHX, which may lead to microbial growth in the air ducts and may impact the performance of downstream systems. Several options have been evaluated to address these concerns. Modifications to the Water Processor Multifiltration Beds and Catalytic Reactor for removal of DMSD were not considered viable, and did not address the issue with PDMS compound degradation of the CHX coating. Design concepts are now in development for removing PDMS compounds from the air stream before they can reach the CHX coating, thus preventing coating degradation and hydrolysis of the PDMS compounds to DMSD. This paper summarizes the current status of the effort to treat these contaminants on ISS.
Publication Date: Jul 12, 2015
Document ID:
20150019534
(Acquired Oct 23, 2015)
Subject Category: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
Report/Patent Number: ICES-2015-074, M15-4838
Document Type: Conference Paper
Meeting Information: International Conference on Environmental Systems Conference; 45th; 12-16 Jul. 2015; Bellevue, WA; United States
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL, United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL, United States
Description: 17p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: SILOXANES; CONTAMINANTS; POTABLE WATER; WATER RECLAMATION; CONDENSATES; EFFLUENTS; MICROWAVE LANDING SYSTEMS; SEPARATORS; DIMETHYL COMPOUNDS; INTERNATIONAL SPACE STATION; CARBON DIOXIDE; HUMIDITY; AIR FLOW
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