Engineering Papers⌕ Search

Engineering topics

Beeson, Harold D.

Publications and source records attributed to Beeson, Harold D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Orion Portable Fire Extinguisher Performance Testing Against a Laptop Lithium-Ion Battery Stored-Energy Fire-Method, Magnesium Fires, and Combustion By-Product Toxicity

As part of the qualification of the International Space Station (ISS) fine water mist portable fire extinguisher (PFE), several test methods were developed to determine firefighting capability against stored-energy sources. The most challenging of these devised stored-energy fire test methods proved to be the Lithium-ion (Li-ion) battery fire test scenario. The Orion crew capsule will utilize a different PFE technology from ISS (water spray rather than water mist), which 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 source for 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% and 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. The PFE stored-energy fire test methodology was modified and testing performed. Initial tests indicated ignition of the laptop magnesium laptop cases was possible. Additional tests were performed to characterize the laptop magnesium case fire behavior in various configurations. 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 laptop magnesium case ignition mitigation strategies need to be further investigated.

Harper, Susana A.↗
NASA NTRS2017

NASA-STD-6001B Test 1 Upward Flame Propagation; Sample Length Impact on MOC Investigation

Understanding 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.

Harper, Susana Tapia↗
NASA NTRS2017

NASA-STD-6001B Test 7: Impact of Test Methodology and Detection Advancements on the Obsolescence of Historical Offgas Data

NASA-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 (Registered trademark) and Aeroglaze (Registered trademark) topcoat highlight the importance of material retesting.

Buchanan, Vanessa D.↗
NASA NTRS2016

Elaborated Odor Test for Extended Exposure

Concerns 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 themselves 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.

Buchanan, Vanessa D.↗
NASA NTRS2016

An Improved Approach for Analyzing the Oxygen Compatibility of Solvents and other Oxygen-Flammable Materials for Use in Oxygen Systems

Solvents used to clean oxygen system components must be assessed for oxygen compatibility, as incompatible residue or fluid inadvertently left behind within an oxygen system can pose a flammability risk. The most recent approach focused on solvent ignition susceptibility to assess the flammability risk associated with these materials. Previous evaluations included Ambient Pressure Liquid Oxygen (LOX) Mechanical Impact Testing (ASTM G86) and Autogenous Ignition Temperature (AIT) Testing (ASTM G72). The goal in this approach was to identify a solvent material that was not flammable in oxygen. As environmental policies restrict the available options of acceptable solvents, it has proven difficult to identify one that is not flammable in oxygen. A more rigorous oxygen compatibility approach is needed in an effort to select a new solvent for NASA applications. NASA White Sands Test Facility proposed an approach that acknowledges oxygen flammability, yet selects solvent materials based on their relative oxygen compatibility ranking, similar to that described in ASTM G63-99. Solvents are selected based on their ranking with respect to minimal ignition susceptibility, damage and propagation potential, as well as their relative ranking when compared with other solvent materials that are successfully used in oxygen systems. Test methods used in this approach included ASTM G86 (Ambient Pressure LOX Mechanical Impact Testing and Pressurized Gaseous Oxygen (GOX) Mechanical Impact Testing), ASTM G72 (AIT Testing), and ASTM D240 (Heat of Combustion (HOC) Testing). Only four solvents were tested through the full battery of tests for evaluation of oxygen compatibility: AK-225G as a baseline comparison, Solstice PF, L-14780, and Vertrel MCA. Baseline solvent AK-225G exhibited the lowest HOC and highest AIT of solvents tested. Nonetheless, Solstice PF, L-14780, and Vertrel MCA HOCs all fell well within the range of properties that are associated with proven oxygen system materials. Tested AITs for these solvents fell only slightly lower than the AIT for the proven AK-225G solvent. Based on these comparisons in which solvents exhibited properties within those ranges seen with proven oxygen system materials, it is believed that Solstice PF, L-14780, and Vertrel MCA would perform well with respect to oxygen compatibility.

Harper, Susan A.↗
NASA NTRS2016

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

Harper, Susana A.↗
NASA NTRS2013

Remarks on Flammability Testing of Aerospace Materials

Agenda for the presentation: (1) Brief background of ISO 16697 (a) Reasons for the approach (b) Stated intent for this International Technical Specification (2) Evolution of initial considerations for the ISO approach (3) Discussion and recommendation

Hirsch, David B.↗
NASA NTRS2010

Pressure Flammability Thresholds of Selected Aerospace Materials

A test program was performed to determine the highest pressure in oxygen where materials used in the planned NASA Constellation Program Orion Crew Exploration Vehicle (CEV) Crew Module (CM) would not propagate a flame if an ignition source was present. The test methodology used was similar to that previously used to determine the maximum oxygen concentration (MOC) at which self-extinguishment occurs under constant total pressure conditions. An upward limiting pressure index (ULPI) was determined, where approximately 50 percent of the materials self-extinguish in a given environment. Following this, the maximum total pressure (MTP) was identified; where all samples tested (at least five) self-extinguished following the NASA-STD-6001.A Test 1 burn length criteria. The results obtained on seven materials indicate that the non-metallic materials become flammable in oxygen between 0.4 and 0.9 psia.

Hirsch, David B.↗
NASA NTRS2009

Review of Alpha-Ketoglutaric Acid (AKGA) Hydrazine and Monomethylhydrazine (MMH) Neutralizing Compound

The Johnson Space Center (JSC) White Sands Test Facility (WSTF) and NASA Engineering and Safety Center (NESC) were requested by NASA Associate Administrator for Space Operations to perform an evaluation of a proposed hydrazine/monomethylhydrazine (MMH) fuel treatment method using alpha-ketoglutaric acid (AKGA). This evaluation request was prompted by preliminary tests at the Kennedy Space Center (KSC), suggesting cost and operational benefits to NASA for the Space Shuttle Program (SSP) and other hardware decontamination and decommissioning, in addition to hydrazine and MMH waste treatment activities. This paper provides the team's position on the current KSC and New Mexico Highlands University (NMHU) efforts toward implementing the AKGA treatment technology with flight hardware, ground support equipment (GSE), hydrazine and MMH spills, and vapor control. This evaluation is current to the last data examined (approximately September 2008).

Dibbern, Andreas W.↗
NASA NTRS2009

Pressure Effects on the Self-Extinguishment Limits of Aerospace Materials

The Orion Crew Exploration Vehicle Module (CM) is being designed to operate in an atmosphere of up to 30% oxygen at a pressure of 10.2 psia for lunar missions. Spacecraft materials selection is based on an upward flammability test conducted in a closed chamber under the worst expected conditions of pressure and oxygen concentration. Material flammability depends on both oxygen concentration and pressure but, since oxygen concentration is the primary driver, all materials are certified in the 30% oxygen, 10.2 psia environment. Extensive data exist from the Shuttle Program at this condition which used relatively the same test methodology as currently used in the Constellation Program. When the CM returns to Earth, a snorkel device will be activated after splashdown to provide outside air to the crew; however, for operational reasons, it is desirable to maximize the time the crew is able to breathe cabin air before the snorkel device is activated. To maximize this time, it has been proposed to raise the partial pressure of oxygen in the CM immediately before reentry while maintaining the total cabin pressure at 14.7 psia. In addition, it has been proposed to leak-test the Orion CM with ambient air at a maximum pressure of 17.3 psia. No data exist to assess how high the cabin oxygen concentration can be at 14.7 psia or 17.3 psia. One is to re-test a large number of materials at these pressures at a significant cost. However, since the maximum oxygen concentration (MOC) at which a material will self-extinguish has been determined for a variety of spacecraft materials as a function of pressure, a second alternative is to use existing data to estimate the MOC at 14.7 psia and 17.3 psia. This data will be examined in this paper and an analysis presented to determine the oxygen concentrations at the increased pressures that will result in self-extinguishment of a material. This analysis showed that the oxygen concentration for the Orion CM at 14.7 psia cannot be set higher than 25.6% without potentially invalidating the materials flammability certification in 30% oxygen at 10.2 psia for some materials. Materials certified under these conditions would still be self-extinguishing in ambient air at 17.3 psia. alternative

Hirsch, David B.↗
NASA NTRS2005

Rr2004 Test1 and 4 Data Analysis

Test 1 data analysis for Kydex, Royal Blue Cotton, and Silicon along with test 4 data analysis for Raychem Electrical Wire is presented.

Beeson, Harold D.↗
NASA NTRS2005

A Brief Study on Toxic Combustion Products of the Polymers Used in High-Pressure Oxygen Systems

One likely cause of polymer ignition in a high-pressure oxygen system is the adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper investigates the feasibility of using the NASA pneumatic-impact system to conduct adiabatic-compression combustion tests and determines the toxic combustion products produced from the burning of five selected polymers. Five polymers commonly used in high-pressure oxygen systems, Zytel(Registered TradeMark) 42 (Nylon 6/6), Buna N (nitrile rubber), Witon(Registered TradeMark) A (copolymer of vinylidene fluoride and hexafluoropropylene), Neoflon(Registered TradeMark) (polychlorotrifluoroethylene), and Teflon(Registered TradeMark) (polytetrafluoroethylene), were tested in the NASA pneumatic-impact test system at 17.2-MPa oxygen pressure. The polymers were ignited and burned; combustion products were collected in a stainless-steel sample bottle and analyzed using various methods. The results show that the NASA pneumatic-impact system is an appropriate test system to conduct adiabatic-compression combustion tests and to collect combustion products for further chemical analysis. The composition of the combustion product gas generated from burning the five selected polymers are presented and discussed.

Hshieh, Fu-Yu↗
NASA NTRS2005

An Approach to Evaluate Precision and Inter-Laboratory Variability of Flammability Test Methods for Aerospace Materials

Materials selection for spacecraft is based on conventional flammability or ignition sensitivity acceptance tests. Current procedures for determining the inter-laboratory repeatability and reproducibility of aerospace materials flammability tests are not considering the dependence of data variability on test conditions and consequently attempts to characterize the precision of these methods were not successful. The inter-laboratory data variability is determined with tests conducted under arbitrary conditions, which consequently may not provide sufficient information to enable adequate determination of a method's precision. For evaluating the precision of NASA's flammability test methods, the protocol recommended includes selecting critical parameters and determining the 50% failure point by considering the specific failure criteria of each method using the critical parameter as a variable. Upon performing inter-laboratory round robin testing using this approach, the laboratories' performance could be evaluated by comparing the repeatability of the 50% failure point and/or the repeatability of critical conditions where the probabilities of passing and failing are unity, i.e., the transition zone repeatability. When a sufficient amount of data has been acquired with this method, an adequate estimation of precision of aerospace materials flammability test methods will be possible.

Hirsch, David↗
NASA NTRS2004

A Preliminary Study on the Toxic Combustion Products Testing of Polymers Used in High-Pressure Oxygen Systems

One likely cause of polymer ignition in a high-pressure oxygen system is adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative _ pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper reports the preliminary results of toxic combustion product testing of selected polymers in a pneumatic-impact test system. Five polymers commonly used in high-pressure oxygen systems, Nylon 6/6, polychlorotrifluoroethylene (CTFE), polytetrafluoroethylene (PTFE), fluoroelastomer (Viton(TradeMark) A), and nitrile rubber (Buna N), were tested in a pneumatic-impact test system at 2500- or 3500-psia oxygen pressure. The polymers were ignited and burned, then combustion products were collected in a stainless-steel sample bottle and analyzed by GC/MS/IRD, GC/FID, and GC/Methanizer/FID. The results of adiabatic-compression tests show that combustion of hydrocarbon polymers, nitrogen-containing polymers, and halogenated polymers in high-pressure oxygen systems are relatively complete. Toxicity of the combustion product gas is presumably much lower than the combustion product gas generated from ambient-pressure oxygen (or air) environments. The NASA-Lewis equilibrium code was used to determine the composition of combustion product gas generated from a simulated, adiabatic-compression test of nine polymers. The results are presented and discussed.

Hshieh, Fu-Yu↗
NASA NTRS2003

Effect of Molding and Machining on Neoflon CTFE M400H Polychlorotrifluoroethylene Rod Stock and Valve Seat Properties

Since 1997 numerous fires have been reported to the Food and Drug Administration involving cylinder valves installed on medical use oxygen cylinders sold and operated within the United States. All of the cylinder valves in question had polychlorotrifluoroethylene (PCTFE) valve seats. Subsequent failure analysis showed that the main seat was the primary source of ignition. A review of the incidents involving cylinder valve fires indicated three possible ignition mechanisms: contaminant promotion, flow friction, and resonance. However, gas purity analysis showed that uncombusted, residual oxygen was within specification. Infrared and energy dispersive spectroscopy further showed that no contaminants or organic compounds were present in the remaining, uncombusted valve seat material or on seat plug surfaces. Therefore, contaminant-promoted ignition did not appear to be responsible for the failures. Observations of extruded material along the outer edge of the coined or loaded seat area produced by cylinder overuse or poppet overload led to concerns that accelerated gas flow across a deformed seat surface could generate enough localized heating to ignite the polymeric seat. Low molecular weight or highly amorphous quick-quenched PCTFE grades might be expected to be especially prone to this type of deformation. Such a failure mechanism has been described as flow friction; however, the corresponding mechanistic parameters are poorly understood. Subsequent revelation of low-temperature dimensional instability by thermomechanical analysis (TMA) in a variety of PCTFE sheet and rod stock samples led to new concerns that PCTFE valve seats could undergo excessive expansion or contraction during service. During expansion, additional extrusion and accompanying flow friction could occur. During contraction, a gap between the seal and adjacent metal surfaces could form. Gas flowing past the gap could, in turn, lead to resonance heating and subsequent ignition as described in ASTM Guide for Evaluation Nonmetallic Materials for Oxygen Service (G 63). Attempts to uncover the origins of the observed dimensional instability were hindered by uncertainties about resin grade, process history, and post-process heat history introduced by machining, annealing, and sample preparation. An approach was therefore taken to monitor property changes before and after processing and machining using a single, well-characterized lot of Neoflon CTFE.1 M400H resin. A task group consisting of the current PCTFE resin supplier, two molders, and four valve seat manufacturers was formed, and phased testing on raw resin, intermediate rod stock, and finished valve seats initiated. The effect of processing and machining on the properties of PCTFE rod stock and oxygen gas cylinder valve seats was then determined. Testing focused on two types of extruded rod stock and one type of compression-molded rod stock. To accommodate valve seat manufacturer preferences for certain rod stock diameters, two representative diameters were used (4.8 mm (0.1875 in.) and 19.1 mm (0.75 in.)). To encompass a variety of possible sealing configurations, seven different valve seat types with unique geometries or machining histories were tested. The properties investigated were dimensional stability as determined by TMA, specific gravity, differential scanning calorimetry (DSC), compressive strength, zero strength time, and intrinsic viscosity. Findings are discussed in the context of polymer structure-process-property relationships whenever possible.

Waller, Jess M.↗