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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Flow in the Proximity of the Pin-Tool in Friction Stir Welding and Its Relation to Weld Homogeneity

In the Friction Stir Welding (FSW) process a rotating pin inserted into a seam literally stirs the metal from each side of the seam together. It is proposed that the flow in the vicinity of the pin-tool comprises a primary rapid shear over a cylindrical envelope covering the pin-tool and a relatively slow secondary flow taking the form of a ring vortex about the tool circumference. This model is consistent with a plastic characterization of metal flow, where discontinuities in shear flow are allowed but not viscous effects. It is consistent with experiments employing several different kinds of tracer: atomic markers, shot, and wire. If a rotating disc with angular velocity w is superposed on a translating continuum with linear velocity omega, the trajectories of tracer points become circular arcs centered upon a point displaced laterally a distance v/omega from the center of rotation of the disc in the direction of the advancing side of the disc. In the present model a stream of metal approaching the tool (taken as the coordinate system of observation) is sheared at the slip surface, rapidly rotated around the tool, sheared again on the opposite side of the tool, and deposited in the wake of the tool. Local shearing rates are high, comparable to metal cutting in this model. The flow patterns in the vicinity of the pin-tool determine the level of homogenization and dispersal of contaminants that occurs in the FSW process. The approaching metal streams enfold one another as they are rotated around the tool. Neglecting mixing they return to the same lateral position in the wake of the tool preserving lateral tracer positions as if the metal had flowed past the tool like an extrusion instead of being rotated around it. (The seam is, however, obliterated.) The metal stream of thickness approximately that of the tool diameter D is wiped past the tool at elevated temperatures drawn out to a thickness of v/2(omega) in the wiping zone. Mixing distances in the wiping zone are multiplied in the unfolded metal. Inhomogeneities on a smaller scale than the mixing length are obliterated, but structure on a larger scale may be transmitted to the wake of a FSW weld.

Nunes, Arthur C., Jr.↗
NASA NTRS2005

X-Ray Fluorescence Solvent Detection at the Substrate-Adhesive Interface

With environmental regulations limiting the use of volatile organic compounds, low-vapor pressure solvents have replaced traditional degreasing solvents for bond substrate preparation. When used to clean and prepare porous bond substrates such as phenolic composites, low vapor pressure solvents can penetrate deep into substrate pore networks and remain there for extended periods. Trapped solvents can interact with applied adhesives either prior to or during cure, potentially compromising bond properties. Currently, methods for characterizing solvent time-depth profiles in bond substrates are limited to bulk gravimetric or sectioning techniques. While sectioning techniques such as microtome allow construction of solvent depth profiles, their depth resolution and reliability are limited by substrate type. Sectioning techniques are particularly limited near the adhesive-substrate interface where depth resolution is further limited by adhesive-substrate hardness and, in the case of a partially cured adhesive, mechanical properties differences. Additionally, sectioning techniques cannot provide information about lateral solvent diffusion. Cross-section component mapping is an alternative method for measuring solvent migration in porous substrates that eliminates the issues associated with sectioning techniques. With cross-section mapping, the solvent-wiped substrate is sectioned perpendicular rather than parallel to the wiped surface, and the sectioned surface is analyzed for the solvent or solvent components of interest using a two-dimensional mapping or imaging technique. Solvent mapping can be performed using either direct or indirect methods. With a direct method, one or more solvent components are mapped using red or Raman spectroscopy together with a moveable sample stage and/or focal plane array detector. With an indirect method, an elemental "tag" not present in the substrate is added to the solvent before the substrate is wiped. Following cross sectioning, the tag element can then be mapped by its characteristic x-ray emission using either x-ray fluorescence, or electron-beam energy-and wavelength-dispersive x-ray spectrometry. The direct mapping techniques avoid issues of different diffusion or migration rates of solvents and elemental tags, while the indirect techniques avoid spectral resolution issues in cases where solvents and substrates have adjacent or overlapping peaks. In this study, cross-section component indirect mapping is being evaluated as a method for measuring migration of d-limonene based solvents in glass-cloth phenolic composite (GCP) prior to and during subsequent bonding and epoxy adhesive cure.

Wurth, Laura↗
NASA NTRS2013

Radio Science Measurements with Suppressed Carrier

Radio Science started when it became apparent with early Solar missions that occultations by planetary atmospheres would affect the quality of radio communications. Since then the atmospheric properties and other aspects of planetary science, solar science, and fundamental physics were studied by scientists. Radio Science data was always extracted from a received pure residual carrier (without data modulation). For some missions, it is very desirable to obtain Radio Science data from a suppressed carrier modulation. In this paper we propose a method to extract Radio Science data when a coded suppressed carrier modulation is used in deep space communications. Type of modulation can be BPSK, QPSK, OQPSK, MPSK or even GMSK. However we concentrate mostly on BPSK modulation. The proposed method for suppressed carrier simply tries to wipe out data that acts as an interference for Radio Science measurements. In order to measure the estimation errors in amplitude and phase of the Radio Science data we use Cramer-Rao bound (CRB). The CRB for the suppressed carrier modulation with non-ideal data wiping is then compared with residual carrier modulation under the same noise condition. The method of derivation of CRB for non-ideal data wiping is an innovative method that presented here. Some numerical results are provided for coded system.

Cramer-Rao bound↗
DOE OSTI2020

Temporal Characterization of Tritium Smear Activities

Tritium collection efficiency varies as a function of smear media. The use of porous smear materials leads to an increase in the measured tritium activity as a function of time when the measurement is performed with liquid scintillation counters. Operational inclusion of the efficiency differences and the time dependence of the tritium smear activity is necessary to preclude inadvertently releasing materials or areas. Thomas Jefferson National Laboratory Radiological Control Department identified a contaminated stainless steel containment vessel that previously housed a target containing more than 37 TBq of tritium. The item was systematically sectioned and surveyed to compare three smear types: water-wetted cotton swabs, water-wetted paper smears, and ethanol-wetted Styrofoam wipes (NUC-Wipes™). The total activity of each section was determined using repeated decontamination. The time dependence of the measured activity was also studied. The measured activity of both paper smears and cotton swabs showed significant time dependence. The cotton swabs also showed significantly reduced collection efficiency. Given the widespread use of both of these media in routine contamination surveys, site operational limits were derived using fitted curves for time dependence and average efficiency results. In conclusion, the use of these more restrictive limits allows for rapid measurement of tritium smears while ensuring regulatory compliance.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Removal of radon progeny from delicate surfaces

210 Po α-decay-driven neutron background is a concern for many rare event search experiments. It is a difficult to control background because its radiogenic component depends on the air exposure history of parts. In this study, we demonstrate that about half of the radon progeny 210 Po can be removed from copper and silicon surfaces relatively easily by wiping a copper sample with acetone-wetted tissue and a silicon detector with acetone soaked cotton balls. For a copper sample, we demonstrate that long-lived 210 Pb is removed with similar effectiveness. For copper, allocated the longest counting time, additional wiping was found to be largely ineffective. For silicon, the removal effectiveness has large uncertainties. Additional cleaning showed a small but statistically significant effect. Here, capitalizing on this trivial cleaning step will allow experiments to relax their requirements on the allowable air exposure time during construction, leading to cost and time savings.

Radioactivity↗
DOE OSTI2021

Corrosion Behavior of Laser-Interference Structured AA2024 Coated with a Chromate-Containing Epoxy Primer

In this study, the corrosion behavior of laser-interference treated AA2024-T3 specimens, which are coated with a primer, is presented. The surface of as-received AA2024-T3 specimens were laser-interference structured by splitting the primary beam of a Q-switched Nd:YAG pulsed nanosecond laser into two beams and focusing them to the same spot on the specimen surface. After being stored in plastic cases for up to 70 d, without any additional cleaning, the specimens were spray painted with a chromate-containing epoxy primer, CA7233, compliant to MIL-PRF-23377 Type I Class C2 specification. The corrosion behavior of laser-interference specimens was assessed against that of specimens prepared by chromated conversion coating and sulfuric acid anodizing treatments. After the ASTM B117 corrosion exposure, it was found that the laser processed specimens exhibited only few blisters. On one hand, most specimens prepared at a laser fluence of 1.78 J/cm 2 , without any additional chemical cleaning, were found to develop one very small blister after only 96 h of exposure. However, the growth of these blisters was not significant even after 1,000 h of salt spray exposure. On the other hand, only a fraction of the specimens prepared at a laser fluence of 1.24 J/cm 2 and acetone wiped right after the laser structuring were found to develop several tiny blisters after 790 h and longer exposure. Overall, it was found that the corrosion damage was minimized at a laser rastering speed of 4 mm/s, a condition for which only 33% of specimens developed very minor corrosion damage. Furthermore, the ASTM D1654 creepage ratings, which was used to evaluate the corrosion damage along the scribe lines, were found to be at least nine for all coated panels. These results indicate that the laser-interference technique with the additional acetone wiping has the potential to be further developed as a nonchemical surface preparation technique for chromate-containing epoxy primers coating systems.

36 MATERIALS SCIENCE↗
NASA NTRS1977

The use of twin screw extruders for feeding coal against pressures of up to 1500 PSI

Recent tests with a twin-screw, co-rotating extruder which was successfully used to convey and feed coal against pressures of up to 1500 psi are described. Intermeshing and self-wiping, co-rotating twin-screws give greatly improved conveying and pressure built-up capabilities and avoid hangup and eventual decomposition of coal particles in the screw flights. The conveying action of intermeshing, self-wiping, co-rotating extruder systems approaches that of a positive displacement pump. With this feature, it is possible to maintain very accurate control over all aspects of product conveyance in the extruder, i.e., intake, conveyance and pressure buildup.

Wiedmann, W.↗
NASA NTRS1989

Contamination removal using various solvents and methodologies

Critical and non-critical bonding surfaces must be kept free of contamination that may cause potential unbonds. For example, an aft-dome section of a redesigned solid rocket motor that had been contaminated with hydraulic oil did not appear to be sufficiently cleaned when inspected by the optically stimulated electron emission process (Con Scan) after it had been cleaned using a hand double wipe cleaning method. As a result, current and new cleaning methodologies as well as solvent capability in removing various contaminant materials were reviewed and testing was performed. Bonding studies were also done to verify that the cleaning methods used in removing contaminants provide an acceptable bonding surface. The removal of contaminants from a metal surface and the strength of subsequent bonds were tested using the Martin Marietta and double-wipe cleaning methods. Results are reported.

Jeppsen, J. C.↗
NASA NTRS1997

Space Shuttle Reusable Solid Rocket Motor (RSRM) Hand Cleaning Solvent Replacement at Kennedy Space Center (KSC)

At Kennedy Space Center (KSC), Thiokol Corporation provides the engineering to assemble and prepare the Space Shuttle Reusable Solid Rocket Motor (RSRM) for launch. This requires hand cleaning over 86 surfaces including metals, adhesives, rubber and electrical insulations, various painted surfaces and thermal protective materials. Due to the phase-out of certain ozone depleting chemical (ODC) solvents, all RSRM hand wipe operations being performed at KSC using l,l,1-trichloroethane (TCA) were eliminated. This presentation summarizes the approach used and the data gathered in the effort to eliminate TCA from KSC hand wipe operations.

Keen, Jill M.↗
NASA NTRS2004

Evaluation of various cleaning methods to remove bacillus spores from spacecraft hardware materials

A detailed study was made of the biological cleaning effectiveness, defined in terms of the ability to remove bacterial spores, of a number of methods used to clean hardware surfaces. Aluminum (Al 6061) and titanium (Ti 6Al-4V) were chosen for the study as they were deemed the two materials most likely to be used in spacecraft extraterrestrial sampler construction. Metal coupons (1 cm x 2.5 cm) were precleaned and inoculated with 5.8 x 10(3) cultivable Bacillus subtilis spores, which are commonly found on spacecraft surfaces and in the assembly environments. The inoculated coupons were subsequently cleaned using: (1) 70% isopropyl alcohol wipe; (2) water wipe; (3) multiple-solvent flight-hardware cleaning procedures used at the Jet Propulsion Laboratory (JPL); (4) Johnson Space Center-developed ultrapure water rinse; and (5) a commercial, semi-aqueous, multiple-solvent (SAMS) cleaning process. The biological cleaning effectiveness was measured by agar plate assay, sterility test (growing in liquid media), and epifluorescent microscopy. None of the cleaning protocols tested completely removed viable spores from the surface of the aluminum. In contrast, titanium was capable of being cleaned to sterility by two methods, the JPL standard and the commercial SAMS cleaning process. Further investigation showed that the passivation step employed in the JPL standard method is an effective surface sterilant on both metals but not compatible with aluminum. It is recommended that titanium (Ti 6Al-4V) be considered superior to aluminum (Al 6061) for use in spacecraft sampling hardware, both for its potential to be cleaned to sterilization and for its ability to withstand the most effective cleaning protocols.

Spores, Bacterial/metabolism↗
NASA NTRS2006

Preventing Ice Before it Forms

In the late 1990s, a team of engineers at Ames Research Center invented an anti-icing fluid to keep ice from building up on airplane wings. Ice on wings can be a serious safety hazard, especially during takeoff, when a sheet of ice the thickness of a compact disc can reduce lift by 25 percent or more. The typical approach to clearing off the ice is to use a deicing solution once the ice has built up. The fluid created by the Ames team, though, when applied to a dry surface, prevents the ice from even forming a surface bond, which saves deicing time and money, while also preventing excessive use of chemical solvents. If, however, the solution is not applied before ice forms, it also serves as a traditional deicing formula. The formula contains propylene glycol, which has a very low freezing point, and a thickener, which helps the fluid adhere to the surface. Ice gathers on top of the formula, and then it can be wiped off with little effort. This thickening agent, a pseudo-plastic, sprays on as a liquid, like lemonade, gels like a lemon sherbet, turns back to a liquid when wiped, and then gels again into its sherbet consistency when left to solidify. The sherbet-gel stage is especially important when the formula is sprayed onto a vertical or steeped surface, as it clings better than a liquid would.

Source record↗
NASA NTRS2007

Center Director's Discretionary Fund 2005 Annual Report

The FY 2005 CDDF projects were selected from the following spaceport and range technology and science areas: fluid system technologies; spaceport structures and materials; command, control, and monitoring technologies; and biological sciences (including support for environmental stewardship). The FY 2005 CDDF research projects involved development of the following: a) Capacitance-based moisture sensors to optimize plant growth in reduced gravity; b) Commodity-free calibration methods; c) Application of atmospheric plasma glow discharge to alter the surface properties of polymers for improved electrostatic dissipation characteristics; d) A wipe-on, wipe-off chemical process to remove lead oxides found in paint; e) A robust metabolite profiling platform for better understanding the "law" of biological regulation; f) An explanation of the excavation processes that occur when a jet of gas impinges on a bed of sand; g) "Smart coatings" to detect and control corrosion at an early stage to prevent further corrosion h) A model that can produce a reliable diagnosis of the quality of a software product; i) The formulation of advanced materials to meet system safety needs to minimize electrostatic charges, flammability, and radiation exposure; j) A lab-based instrument that uses the electro-optic Pockels effect to make static electric fields visible; k) A passive volatile organic compound (VOC) cartridge to filter, identify, and quantify VOCs flowing into or emanating from plant flight experiments.

Nurge, Mark↗
NASA NTRSDate not supplied

Evaluation of Contact Separation Force Testing as a Screening Methodology for Electrical Socket Contacts

During system level testing intermittent and permanent open circuit failures of mated, crimp removable, electrical contact pairs were experienced. The root cause of the failures was determined to be low (but not zero) contact forces applied by the socket contact tines against the engaging pin. The low contact force reduces the effectiveness of the wiping action of the socket tines against the pin. The observed failure mode may be produced when insufficient wiping during mate, demate and small relative movement in use allows for the accumulation of debris or insulating films that electrically separate the contact pair. The investigation identified at least three manufacturing process control problems associated with the socket contacts that enabled shipment of contacts susceptible to developing low contact forces: (1) Improper heat treatment of the socket tines resulting in plastic rather than elastic behavior; (2) Overly thinned socket tines at their base resulting in reduced pin retention forces; (3) Insufficient screening tests to identify parts susceptible to the aforementioned failure mechanisms. The results from an extensive screening program of socket contacts utilizing the industry standard contact separation force test procedures are described herein. The investigation shows this method to be capable of identifying initially weak sockets. However, sockets whose contact retention forces may degrade during use may not be screened out by pin retention testing alone. Further investigations are required to correlate low contact retention forces with increased electrical contact resistance in the presence of insulating films that may accumulate in the use environment.

Christopher Green↗
NASA NTRS2012

The Evolution of Friction Stir Welding Theory at Marshall Space Flight Center

From 1995 to the present the friction stir welding (FSW) process has been under study at Marshall Space Flight Center (MSFC). This is an account of the progressive emergence of a set of conceptual tools beginning with the discovery of the shear surface, wiping metal transfer, and the invention of a kinematic model and making possible a treatment of both metallurgical structure formation and process dynamics in friction stir welding from a unified point of view. It is generally observed that the bulk of the deformation of weld metal around the FSW pin takes place in a very narrow, almost discontinuous zone with high deformation rates characteristic of metal cutting. By 1999 it was realized that this zone could be treated as a shear surface like that in simple metal cutting models. At the shear surface the seam is drawn out and compressed and pressure and flow conditions determine whether or not a sound weld is produced. The discovery of the shear surface was followed by the synthesis of a simple 3- flow kinematic model of the FSW process. Relative to the tool the flow components are: (1) an approaching translational flow at weld speed V, (2) a rotating cylindrical plug flow with the angular velocity of the tool , and (3) a relatively slow ring vortex flow (like a smoke ring) encircling the tool and driven by shoulder scrolls and pin threads. The rotating plug flow picks up an element of weld metal, rotates it around with the tool, and deposits it behind the tool ( wiping metal transfer ); it forms plan section loops in tracers cut through by the tool. Radially inward flow from the ring vortex component retains metal longer in the rotating plug and outward flow expels metal earlier; this interaction forms the looping weld seam trace and the tongue and groove bimetallic weld contour. The radial components of the translational and ring vortex flows introduce parent metal intrusions into the small grained nugget material close to the tool shoulder; if this feature is pronounced, nugget collapse may result. Certain weld features, in particular internal banding seen in transverse section as onion rings and associated surface ridges called tool marks , have long implied an oscillation flow component, but have only recently been attributed in the literature to tool eccentricity. Rotating plug shape, typically a hollow cylinder flared at the end where it sticks to the shoulder, varies as pressure distribution on the tool determines where sticking occurs. Simplified power input estimates balanced against heat loss estimates give reasonable temperature estimates, explain why the power requirement changes hardly at all over a wide range of RPM s, and yield isotherms that seem to fall along boundaries of parameter windows of operation.

Nunes, Arthur C.↗
NASA NTRS2013

Microbiological Sampling Methods and Sanitation of Edible Plants Grown on ISS

Pathogenic microbes on the surfaces of salad crops and growth chambers pose a threat to the health of crew on International Space Station. For astronauts to safely consume spacegrown vegetables produced in NASA's new vegetable production unit, VEGGIE, three technical challenges must be overcome: real-time sampling, microbiological analysis, and sanitation. Raphanus sativus cultivar Cherry Bomb II and Latuca sativa cultivar Outredgeous, two saled crops to be grown in VEGGIE, were inoculated with Salmonella enterica serovar Typhimurium (S. Typhimurium), a bacterium known to cause food-borne illness~ Tape- and swab-based sampling techniques were optimized for use in microgravity and assessed for effectiveness in recovery of bacteria from crop surfaces: Rapid pathogen detection and molecular analyses were performed via quantitative real-time polymerase chain reactiop using LightCycler® 480 and RAZOR® EX, a scaled-down instrument that is undergoing evaluation and testing for future flight hardware. These methods were compared with conventional, culture-based methods for the recovery of S. Typhimurium colonies. A sterile wipe saturated with a citric acid-based, food-grade sanitizer was applied to two different surface materials used in VEGGIE flight hardware that had been contaminated with the bacterium Pseudomonas aeruginosa,. another known human pathogen. To sanitize surfaces, wipes were saturated with either the sanitizer or sterile deionized water and applied to each surface. Colony forming units of P. aeruginosa grown on tryptic soy agar plates were enumerated from surface samples after sanitization treatments. Depending on the VEGGIE hardware material, 2- to 4.5-log10 reductions in colony-forming units were observed after sanitization. The difference in recovery of S. Typhimurium between tape- and swab- based sampling techniques was insignificant. RAZOR® EX rapidly detected S. Typhimurium present in both raw culture and extracted DNA samples.

Parrish, Charles H. II↗
NASA NTRS2013

Characterization of Heat Melt Compactor (HMC) Product Water

The Heat Melt Compactor (HMC) is designed to sterilize and process wastes produced during space missions. Benefits of the HMC include reduction of biohazards to the crew, reduction in volume of wastes that would otherwise require storage, production of radiation shielding tiles, and recovery of water and other resources. Water reuse is critical onboard spacecrafts; it reduces the need for resupply missions and saves valuable storage space. The main sources of water in HMC batches are food, beverages, shampoo, disinfecting wipes, toothpaste, and diapers. Water reclaimed by the HMC was analyzed for concentrations of Na+, NH4+, K+, Mg2+, Ca2+, Cl-­‐, NO2-­‐, Br-­‐, NO3-­‐, PO43-­‐, SO42-­‐, total organic carbon (TOC), total inorganic carbon (TIC), % total solids, and pH. The data are discussed in relation to the current water input characteristics established for the International Space Station Water Processor Assembly system. Batches with higher than average amounts of food produced HMC product water with higher sulfate content, and batches with higher proportions of disinfectant wipes and food yielded HMC product water with higher ammonium concentration. We also compared theoretical chemical composition of HMC product water based on food labels and literature values to experimental results.

Heat Melt Compactor↗
NASA NTRS2015

Veggie ISS Validation Test Results and Produce Consumption

The Veggie vegetable production system flew to the International Space Station (ISS) in the spring of 2014. The first set of plants, Outredgeous red romaine lettuce, was grown, harvested, frozen, and returned to Earth in October. Ground control and flight plant tissue was sub-sectioned for microbial analysis, anthocyanin antioxidant phenolic analysis, and elemental analysis. Microbial analysis was also performed on samples swabbed on orbit from plants, Veggie bellows, and plant pillow surfaces, on water samples, and on samples of roots, media, and wick material from two returned plant pillows. Microbial levels of plants were comparable to ground controls, with some differences in community composition. The range in aerobic bacterial plate counts between individual plants was much greater in the ground controls than in flight plants. No pathogens were found. Anthocyanin concentrations were the same between ground and flight plants, while antioxidant and phenolic levels were slightly higher in flight plants. Elements varied, but key target elements for astronaut nutrition were similar between ground and flight plants. Aerobic plate counts of the flight plant pillow components were significantly higher than ground controls. Surface swab samples showed low microbial counts, with most below detection limits. Flight plant microbial levels were less than bacterial guidelines set for non-thermostabalized food and near or below those for fungi. These guidelines are not for fresh produce but are the closest approximate standards. Forward work includes the development of standards for space-grown produce. A produce consumption strategy for Veggie on ISS includes pre-flight assessments of all crops to down select candidates, wiping flight-grown plants with sanitizing food wipes, and regular Veggie hardware cleaning and microbial monitoring. Produce then could be consumed by astronauts, however some plant material would be reserved and returned for analysis. Implementation of this plan is a step toward developing pick-and-eat food production to supplement the packaged diet on ISS and for future exploration missions where plants could make up a larger portion of the diet. Supported by NASA Space Biology Program.

Food Safety↗
NASA NTRS2017

Solvent Replacement for Hydrochlorofluorocarbon-225 for Cleaning Oxygen System Components

This Technical Memorandum is the result of a 2-year project funded by the Defense Logistics Agency-Aviation, Hazardous Minimization and Green Products Branch, to identify and test two candidate solvents to replace hydrochlorofluorocarbon-225 (HCFC-225) for cleaning oxygen systems. The solvents were also compared to a second solvent composed predominantly of perfluorobutyl iodide (PFBI), which had received limited approval by the United States Air Force (USAF) for hand wipe cleaning of components for aviators’ breathing oxygen systems. The tests performed for this study were based on those reported in AFRL-ML-WP-TR-2003-4040, “The Wipe Solvent Program,” the test program used to qualify Ikon® Solvent P for USAF applications.The study was completed in August 2014, prior to the completion of a more extensive study funded by the NASA Rocket Propulsion Test (RPT) program. The results of the RPT project are reported in NASA/TP-2015-18207, “Replacement of Hydrochlorofluorocarbon–225 Solvent for Cleaning and Verification Sampling of NASA Propulsion Oxygen Systems Hardware, Ground Support Equipment, and Associated Test Systems.” The test methods used in this study for nonvolatile residue (NVR) background, materials compatibility, and cleaning effectiveness were different than those used for the RPT project; a smaller set of materials and contaminants were tested. The tests for this study were complementary to and provided supplementary information for the down-selection process during the course of the test program reported in NASA/TP-2015-218207.

Mitchell, M. A.↗