Browsing by Author "Beeson, Harold"
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Item Applying Flammability Limit Probabilities and the Normoxic Upward Limiting Pressure Concept to NASA STD-6001 Test 1(44th International Conference on Environmental Systems, 2014-07-13) Olson, Sandra L.; Beeson, Harold; Fernandez-Pello, A. CarlosRepeated Test 1 extinction tests near the upward flammability limit are expected to follow a Poisson process trend. This Poisson process trend suggests that rather than define a ULOI and MOC (which requires two limits to be determined), it might be better to define a single upward limit as being where 1/e (where e (=~2.7183) is the characteristic time of the normalized Poisson process) of the materials burn, or, rounding, where approximately 1/3 of the samples fail the test (and burn). Recognizing that spacecraft atmospheres will not bound the entire oxygen-pressure parameter space, but actually lie along the normoxic atmosphere control band, we can focus the materials flammability testing along this normoxic band. A Normoxic Upward Limiting Pressure (NULP) is defined that determines the minimum safe total pressure for a material within the constant partial pressure control band. Then, increasing this pressure limit by a factor of safety, we can define the material as being safe to use at the NULP + SF (where SF is on the order of 10 kPa, based on existing flammability data). It is recommended that the thickest material to be tested with the current Test 1 igniter should be 3 mm thick (1/8”) to avoid the problem of differentiating between an ignition limit and a true flammability limit.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.