Engineering topics

Steinberg, Theodore A.

Publications and source records attributed to Steinberg, Theodore A..

10 records

NASA NTRS2010

Heat Effects of Promoters and Determination of Burn Criterion in Promoted Combustion Testing

Promoted ignition testing (NASA Test 17) [1] is used to determine the relative flammability of metal rods in oxygen-enriched atmospheres. A promoter is used to ignite a metal sample rod, initiating sample burning. If a predetermined length of the sample burns, beyond the promoter, the material is considered flammable at the condition tested. Historically, this burn length has been somewhat arbitrary. Experiments were performed to better understand this test by obtaining insight into the effect a burning promoter has on the preheating of a test sample. Test samples of several metallic materials were prepared and coupled to fast-responding thermocouples along their length. Thermocouple measurements and test video were synchronized to determine temperature increase with respect to time and length along each test sample. A recommended flammability burn length, based on a sample preheat of 500 F, was determined based on the preheated zone measured from these tests. This length was determined to be 30 mm (1.18 in.). Validation of this length and its rationale are presented.

Sparks, Kyle M.↗

NASA NTRS2009

Determination of Pass/Fail Criteria for Promoted Combustion Testing

Promoted ignition testing is used to determine the relative flammability of metal rods in oxygen-enriched atmospheres. In these tests, a promoter is used to ignite each metal rod to start the sample burning. Experiments were performed to better understand the promoted ignition test by obtaining insight into the effect a burning promoter has on the preheating of a test sample. Test samples of several metallic materials were prepared and coupled to fast-responding thermocouples along their length. Various ignition promoters were used to ignite the test samples. The thermocouple measurements and test video was synchronized to determine temperature increase with respect to time and length along each test sample. A recommended length of test sample that must be consumed to be considered a flammable material was determined based on the preheated zone measured from these tests. This length was determined to be 30 mm (1.18 in.). Validation of this length and its rationale are presented.

Sparks, Kyle M.↗

NASA NTRS2000

The Presence of Excess Oxygen in Burning Metallic Materials

Early work on burning of iron rods under conditions of the ATSM/NASA flammability test showed that there was excess oxygen, that is, above stoichiometric requirements for iron(III) oxide, present in the molten product during burning. Since that work, this phenomenon has been confirmed for burning under microgravity conditions and has been observed for a wide range of metals under burning conditions of a single micro-drop at ambient pressures and 20-second microgravity tests under pressurized oxygen-enriched conditions. This paper reviews these experimental observations and discusses the possible thermodynamic analysis for the metals iron, aluminum, and cobalt. The excess oxygen in the burning molten iron oxide was represented as combined to form a series of ferrite ions. For aluminum the excess oxygen is represented as a bridging species and a similar explanation is postulated for the cobalt system.

Wilson, D. Bruce↗

NASA NTRS2000

Flammability: A Review and Analysis

With its founding in 1975, Committee G-4 of the American Society for Testing and Materials (ASTM) embarked on the process of defining the flammability of metallic materials in oxygen-enriched atmospheres. In this process, they are joined by the National Aeronautics and Space Administration (NASA), the National Fire Protection Association (NFPA), and the Compressed Gas Association (CGA). Although none of these organizations has explicitly defined flammability, the following definitions and statements provide a composite understanding of the concept: 1. "This Standard Guide (ASTM G94-92) is concerned primarily with the properties of a material associated with its relative susceptibility to ignition and propagation of combustion." 2. "A material is considered flammable at the maximum use pressure if at least one sample burns more than 6 in. (15.2 cm). At least, five samples must be tested." NASA 3. "Flammable: Capable, when ignited of maintaining combustion under the specified environmental conditions." NFPA 53. 4. "Combustion: A complex sequence of chemical reactions between a fuel and an oxidant accompanied by the evolution of heat, and usually, the emission of light." NFPA 53. and 5. "A safe oxygen-piping transmission or distribution system is one that is designed and installed in accordance with all applicable codes and regulations for the service conditions and locations involved and further meets the special requirements for oxygen services." CGA-G4 Flammability thus equates, after ignition, to propagation of combustion, synonymous with steady state burning, under specified environmental conditions. Properties for which quantitative values are given in ASTM G94-92 and which are used to describe metals flammability consistent with the concept of steady state burning are either system independent properties, such as, enthalpies of reaction, burn ratios, flame temperatures, thermal conductivity, and heat release; or system dependent properties, such as, oxygen index, promoted combustion, threshold pressure and burn rates. Each property is reviewed and analyzed as to whether it provides an absolute or relative measure for flammability. It is shown that burn ratio, as applied to the actual steady state combustion condition, approaches the desired absolute measure of flammability.

Wilson, D. Bruce↗

NASA NTRS1993

Metals combustion in normal gravity and microgravity

The study of the combustion characteristics of metallic materials has been an ongoing area of research at the NASA White Sands Test Facility (WSTF). This research has been in support of both government and industrial operations and deals not only with the combustion of specific metallic materials but also with the relative flammabilities of these materials under similar conditions. Since many of the metallic materials that are characterized at WSTF for aerospace applications are to be used in microgravity environments, it was apparent that the testing of these materials needed to proceed in a microgravity environment. It was believed that burning metallic materials in a microgravity environment would allow the evaluation of the validity of applying normal gravity combustion tests to characterize metallic materials to be used in microgravity environments. It was also anticipated that microgravity testing would provide insight into the general combustion process of metallic materials. The availability of the NASA Lewis Research Center's (LeRC) 2.2-second drop tower provided the necessary facility to accomplish the microgravity portion of the testing while the normal gravity testing was conducted at NASA WSTF. The tests, both at LeRC and WSTF, were conducted in the same instrumented system and utilized the standard metal flammability test of upward propagation burning of cylindrical rod samples.

Steinberg, Theodore A.↗

NASA NTRS1992

The Combustion Phase of Burning Metals

Glassman's hypothesis and burn ratio are examined for their suitability for predicting the phase of combustion of metals. Neither criterion is validated based on either published property values or experimental evidence. Inconsistencies in published property values and definitions are noted. Computer calculations provide a more appropriate descriptions of the compositions of the combustion products and the adiabatic flame temperature of a burning metal at equilibrium. Dissociation temperatures (and product compositions) for 11 metals are computed using a specified quantity of thermal energy and compared with adiabatic flame temperatures.

Steinberg, Theodore A.↗

NASA NTRS1992

Chamber For Microgravity Combustion Experiments

Versatile container for microgravity combustion experiments used in space, in airplane, or in drop tower. Hub top with gas ports encloses chamber. Instrumentation wire fed into chamber through base. Combustion initiated by wire fuse. Oxygen supplied to support combustion, argon to quench it. Container withstands repeated prolonged impacts.

Steinberg, Theodore A.↗

NASA NTRS1992

The Burning of Metals and Alloys in Microgravity

The NASA-Lewis 2.2-sec drop tower has been used to characterize the oxygen-atmosphere burning of several representative spacecraft environment metallic materials in microgravity; these included rods of 2219 Al alloy, 316 stainless steel, Fe, and Ti, as well as sheets and meshes of 316 stainless steel. The absence of buoyant forces does not preclude extinguishment of the combustion process, and the regression rate of the melting interface of the cylindrical rods is significantly greater than in normal gravity. The flammability of such sample shapes as thin sheets, which are known to extinguish in normal gravity, is enhanced. Volatile combustion products are generated, in contrast to the normal gravity regime.

Steinberg, Theodore A.↗

NASA NTRS1989

Promoted combustion of nine structural metals in high-pressure gaseous oxygen - A comparison of ranking methods

The 316, 321, 440C, and 17-4 PH stainless steels, as well as Inconel 600, Inconel 718, Waspaloy, Monel 400, and Al 2219, have been evaluated for relative nonflammability in a high-pressure oxygen environment with a view to the comparative advantages of four different flammability-ranking methods. The effects of changes in test pressure, sample diameter, promoter type, and sample configuration on ranking method results are evaluated; ranking methods employing velocity as the primary ranking criterion are limited by diameter effects, while those which use extinguishing pressure are nonselective for metals with similar flammabilities.

Steinberg, Theodore A.↗

NASA NTRS1989

Combustion of 316 stainless steel in high-pressure gaseous oxygen

Upward combustion of 316 stainless steel (SS) rods is discussed and a combustion model is presented. The effects of varying oxygen pressure and rod diameter on the rate limiting processes for combustion of 316 SS are evaluated. The rate-limiting steps for combustion up 316 SS rods are shown to be dependent on the incorporation and mass transport of oxygen in the molten mass, and heat transfer between the molten mass and rod. Both these rate-limiting steps are shown to be dependent on rod diameter. Small (d/r/ = 0.051 cm) 316 SS rods are shown to be dependent on convective heat transfer, and larger rods (d/r/ not less than 0.32 cm) are shown to be dependent on oxygen incorporation and mass transport in the molten mass.

Benz, Frank↗