Browsing by Author "Harper, Susana"
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Item Characterization of Laptop Fires in Spacecraft(49th International Conference on Environmental Systems, 2019-07-07) Padilla, Rosa; Dietrich, Daniel; Lynch, Kelly; Juarez, Alfredo; Harper, Susana; Nagel, Christopher; Ruff, Gary; Urban, DavidAn accidental fire involving the Lithium-Ion (Li-ion) battery in a laptop computer is one of the most likely fire scenarios on-board a spacecraft. These fires can occur from a defect in the battery that worsens with time, over-charging the battery and leading to failure or accidental damage caused by thermal runaway. While this is a relatively likely fire scenario, very little is known about the how a laptop computer fire would impact a sealed spacecraft. The heat release would likely cause a pressure rise, possibly exceeding the pressure limit of the vehicle and causing a relief valve to open. The combustion products from the fire could pose a short-term and long-term health hazard to the crew and the fire itself could cause injury to the crew and damage to the spacecraft. Despite the hazard posed by a laptop fire, there is little quantitative data on the fire size, heat release and toxic product formation. This paper presents the results of initial attempts to quantify the fire resulting from a failed laptop battery tested at the NASA White Sands Test Facility (WSTF). The fire size and characteristics such as maximum heat release rate, total heat release, maximum temperatures and fire duration are determined. Using existing models and correlations for fires, the measured fire characteristics are extrapolated to laptop fires on a vehicle the approximate size of the Orion spacecraft.Item Elaborated Odor Test for Extended Exposure(46th International Conference on Environmental Systems, 2016-07-10) Buchanan, Vanessa; Henry, Emily; Harper, SusanaConcerns were raised when incidental exposure to a proprietary bonding material revealed the material had an irritating odor. The NASA-STD-6001B document describes a supplemental test method option for programs to evaluate materials with odor concerns (Test 6, Odor Assessment). In addition to the supplemental standard odor assessment with less than 10 seconds of exposure, the NASA White Sands Test Facility (WSTF) Materials Flight Acceptance Testing section was requested to perform an odor test with an extended duration to evaluate effects of an extended exposure and to more closely simulate realistic exposure scenarios. With approval from the NASA Johnson Space Center Industrial Hygienist, WSTF developed a 15-minute odor test method. WSTF performed this extended-duration odor test to evaluate the odor and physical effects of the bonding material configured between two aluminum plates after the safety of the gas was verified via toxicity analysis per NASA-STD 6001B Test 7, Determination of Offgassed Products. During extended-duration testing, odor panel members were arranged near the test material in a small room with the air handlers and doors closed to minimize dilution. The odor panel members wafted gas toward them and recorded their individual assessments of odor and physical effects at various intervals during the 15-minute exposure and posttest. A posttest interview was conducted to obtain further information. Testing was effective in providing data for comparison and selection of an optimal offgassing and odor containment configuration. The developed test method for extended exposure is proposed as a useful tool for further evaluating materials with identified odors of concern if continued use of the material is anticipated.Item High Risk Spacecraft Materials Offgassing(2024 International Conference on Environmnetal Systems, 2024-07-21) Buchanan, Vanessa; Silva, Emmanuel; Padilla, Julio; Greene, Benjamin; Reys, Ilse; Harper, SusanaNASA-STD-6001B Determination of Offgassed Products (Test 7) provides the offgassing characteristics under standardized conditions for materials and assembled articles to be located within habitable spacecraft environments. Experience with Test 7 has found certain material types above many others to be of high risk for offgassing undesirable compounds aboard spacecraft. Formaldehyde and acrolein are historically high T value offgassed components of the offgassed compound target list because they have low spacecraft maximum allowable concentration (SMAC) values assigned by the JSC Toxicology Group. Carbon disulfide, benzene, acrylonitrile, and furan are additional target compounds of concern due to their lower thresholds of toxicity as determined by the JSC Toxicology Group. Materials offgassing siloxanes are also of concern due to their degradation effects on environmental control and life support system (ECLSS) components and performance. Spacecraft materials and articles defined in this manuscript as high risk were identified after examining and condensing data for these compounds of concern from approximately 3000 tests performed over 30 years. Summaries of high risk material and article types based on highest Multi-purpose Crew Vehicle (MPCV) T values are also presented. Historical analysis shows high risk components are produced largely from test materials and articles in the general categories of electronic/powered components, foams, paints/coatings/films, adhesives/tapes, epoxy/resins, liquids/gels, Nomex� with surface treatments, markers/pens/inks, dry film lubricants, thermoplastics, hygiene items (deodorants, lip balms), and silicone rubber. These data are intended to be a resource for spacecraft materials and processes managers, designers and toxicologists. High risk materials and articles intended for use aboard spacecraft should be tested in accordance with NASA-STD-6001B Test 7.Item NASA-STD-6001B Test 1 Upward Flame Propagation; Sample Length Impact on MOC Investigation(47th International Conference on Environmental Systems, 2017-07-16) Juarez, Alfredo; Harper, Susana; Woods, BrentonUnderstanding the combustion behavior of materials in the elevated oxygen environments of habitable spacecraft is of utmost importance to crew safety and mission success. Currently, certification for unrestricted flight usage of a material with respect to flammability involves passing the Upward Flame Propagation Test of NASA-STD-6001B (Test 1). This test evaluates materials in a standardized test configuration for two failure criteria: self-extinguishment within 15 cm (6 in.) and the propensity of flame propagation by means of flaming material transfer. By the NASA standard, full-length samples are 30 cm (12 in.) in length; however, factors independent of the test method such as limited material availability or various nonstandard test configurations limit the full pretest sample lengths available for test. This paper characterizes the dependence, if any, of pretest sample length on NASA-STD-6001B Test 1 results. Testing was performed using the Maximum Oxygen Concentration (MOC) Threshold Method to obtain a data set for each sample length tested. In addition, various material types, including cloth (Nomex), foam (TA-301) and solids (Ultem), were tested to investigate potential effects of test specimen types. Though additional data needs to be generated to provide statistical confidence, preliminary findings are that use of variable sample lengths has minimal impact on NASA-STD-6001B flammability performance and MOC determination.Item NASA-STD-6001B Test 7: Impact of Test Methodology and Detection Advancements on the Obsolescence of Historical Offgas Data(47th International Conference on Environmental Systems, 2017-07-16) Buchanan, Vanessa; Harper, Susana; Woods, Brenton; Beeson, Harold; Perez, Horacio; Ryder, Valerie; Pedley, Michael; Tapia, Alma StephanieNASA-STD-6001B states “all nonmetals tested in accordance with NASA-STD-6001 should be retested every 10 years or as required by the responsible program/project.” The retesting of materials helps ensure the most accurate data are used in material selection. Manufacturer formulas and processes can change over time, sometimes without an update to product number and material information. Material performance in certain NASA-STD-6001 tests can be particularly vulnerable to these changes, such as material offgas (Test 7). In addition, Test 7 analysis techniques at NASA White Sands Test Facility were dramatically enhanced in the early 1990s, resulting in improved detection capabilities. Low level formaldehyde identification was improved again in 2004. Understanding the limitations in offgas analysis data prior to 1990 puts into question the validity and current applicability of that data. Case studies on Super Koropon® and Aeroglaze® topcoat highlight the importance of material retesting.Item Orion Portable Fire Extinguisher Performance Testing against a Laptop Lithiom-Ion Battery Stored Energy Fire - Method, Magnesium Fires, & Combustion By-product Toxicity(48th International Conference on Environmental Systems, 2018-07-08) Harper, Susana; Juarez, Alfredo; Woods, Brenton; Beeson, Harold; Coan-Skow, Mary Rachel; Nagel, Christopher; Casper, Stephanie; Tarver, SterlingAs part of the qualification of the International Space Station (ISS) Fine Water Mist (FWM) Portable Fire Extinguisher (PFE) several test methods were developed to determine against stored energy sources. The most challenging of these devised stored energy fire test methods proved to be the Li-Ion battery fire test scenario. The intended use of new water based PFE technology on the Orion Crew capsule spurred the need for the same type of evaluation focused on the sources of stored energy slated for use on Orion. Laptops were identified as a realistic potential source for potential stored energy fires requiring a modified li-ion battery fire test scenario. In addition to open test cell (ambient oxygen concentration) testing to evaluate new proposed PFE performance, sealed chamber (20.9 & elevated oxygen concentration) testing was also performed. Chamber testing included combustion product sampling at various fire progression points for analysis and application to Orion emergency equipment design and response planning. Fire extinguisher stored energy fire test methodology was modified and testing performed. Initial tests indicated ignition of the magnesium cases was possible and further testing was performed to assess the damage potential of the new risk as well as the use of new Water Spray PFE as a means to combat this type of fire. The new Water Spray PFE technology proved effective in extinguishing laptop stored energy fires and much was learned in the way these types of fires progressed., Findings indicate potential Mg ignition mitigation strategies to be further investigated.Item Predicting the Microgravity Performance of Terrestrial Portable Fire Extinguishers(2024 International Conference on Environmnetal Systems, 2024-07-21) Abney, Morgan; Weislogel, Mark; Harper, Susana; Juarez, Alfredo; Willard, Doug; Provin, Tim; Goetter, Chris; Simpkins, Patrick; Santamaria, Rudy; Chen, Yongkang; Dietrich, Daniel; Urban, David; Williams, DavePortable fire extinguishers (PFEs) are a key component of spacecraft emergency response systems. The International Space Station uses custom PFEs to meet the unique microgravity and enclosed space requirements of the vehicle. For future missions, terrestrial commercial off-the-shelf (COTS) PFEs may offer more economical solutions. Depending on the design and layout of the targeted locations and chosen commodity, however, reduced gravity may affect the performance of terrestrial PFEs (e.g., two-phase systems). To better characterize the potential of using COTS hardware, two terrestrial PFEs, one charged with HFC-227ea pressurized with nitrogen gas and one charged with carbon dioxide, were modeled to predict performance in both 1-g and microgravity environments. Testing was conducted in 1-g in best and worst case configuration to validate the model. Here we provide a detailed description of the model, report the methods of PFE testing, and discuss the predicted effects of microgravity on PFE performance.