Mr. Newton's Publications
Effect of Molding & Machining on Neoflon CTFE M400H Polychlorotrifluoroethylene Rod Stock & Valve Seat Properties
Oxygen Fire Cause and Origin Analysis of the CUMA V2 Underwater Breathing Apparatus
Cause And Origin Analyses Of Two Large Industrial Oxygen Valve Fires
Using ASTM Standard Guide G88 to Identify and Rank System-Level Hazards in Large-Scale Oxygen Systems
Failure Investigation of a Welding Regulator Fire
Failure Analysis of Aluminum-Bodied Medical Regulators
Potential Ignition Mechanism of Buna-N O-Rings in Liquid-Oxygen
Comparison of the Dimensional Stability of Kel-F 81 and Neoflon CTFE M400H Polychlorotrifluoroethylenes Used in Valve Seat Applications
A Database for Metallic and Nonmetallic Materials Commonly Utilized in Oxygen Service
A 6000 psig Gaseous Oxygen Impact Test System for Materials and Components Compatibility Evaluations
Case Study of an Oxygen-Acetylene Cutting Torch Failure and Measured Overpressures Due to Flashback Reactions
Ignition of PTFE-Lined Flexible Hoses by Rapid Pressurization with Oxygen
Promoted Ignition of Oxygen Regulators
Analysis Tools Used to Evaluate Oxygen Hazards and the Oxygen Compatibility of Metals
Mechanical Impact of Aluminum Alloy Gas Cylinder Pressurized with Oxygen
Materials Compatibility with Nitrogen Trifluoride (NF3)
Promoted Ignition of a Cylinder Valve in NF3
Investigation of Oxygen-Acetylene Flashback Reactions in Welding Hoses
Investigation of Oxygen-Acetylene Flashback Reactions in Welding Hoses
Newton, B.E., Pryor, D., Chiffoleau, G.J.A., Beeson, H.; "Investigation of Oxygen-Acetylene Flashback Reactions in Welding Hoses," J. ASTM Intl., Vol. 3, No. 5, ASTM International, West Conshohocken, PA, 2006, Paper ID JAI13550.
KEYWORDS: detonation, oxyacetylene, welding, flashback, backfire, forensic, reconstruction, backfire, sustained-backfire
ABSTRACT: A common concern in the welding industry is the development of conditions wherein an oxygen-acetylene (i.e., oxyacetylene) flashback reaction can propagate into a welding hose causing it to burst due to the rapid localized pressurization associated with an oxygen-acetylene deflagration-to-detonation transition. The investigation of a recent welding hose fire resulted in testing to evaluate the conditions under which detonations could be generated within welding hoses and the conditions in which welding hoses would burst when exposed to these events. This paper reports on elements of the welding hose fire investigation, the conditions for flashback reactions to develop, and the analytical work performed during the accident reconstruction to characterize deflagration-to-detonation transition within typical welding hoses. This paper also suggests physical and chemical criteria that are characteristic to welding hose ruptures due to flashback detonations.
Promoted Ignition of a Cylinder Valve in NF3
Chiffoleau, G.J.A., Newton, B.E., Chou, T., Wilson, B.; "Promoted Ignition of a Cylinder Valve in NF3," J. ASTM Intl., Vol. 3, No. 4, ASTM International, West Conshohocken, PA, 2006, Paper ID JAI13535.
ABSTRACT: Nitrogen trifluoride (NF3) is used in the manufacturing process of semiconductors and is believed to be 1.5 times more oxidizing than oxygen. Compatibility data of materials with NF3 is limited and has only recently been addressed by companies which routinely handle NF3. Even more limited is the ability to conduct configuration testing of components in NF3 to evaluate kindling chain and reaction effects. In NF3 systems, the cylinder valve is subjected to severe operating conditions, and is known to have experienced fires in service. A new test approach was developed to positively ignite the non-metallic seat of a cylinder valve pressurized with NF3. The goal of the work was to investigate whether the ignition of the seat would kindle the surrounding sub-components of the valve and ultimately whether a kindling reaction would develop that could breach the valve body. The ignition concept of the test method consists of electrically heating a thin section of wire positioned across the seat to act as a promoter. The concept required minimal modifications to the valve and the overall valve design remained consistent with normal operation. The assembled valves were tested at a pressure of 1500 psig and no burn-through was observed during any test. The post-test valve disassembly and inspection confirmed the wire fused and successfully ignited the seat but the seat retainer and surrounding sub-components did not kindle. All of the other parts of the valve were unaffected by the ignition and consumption of the non-metallic seat. The new test provides an approach for evaluating the propagation propensity of NF3 components containing nonmetallic materials.
Materials Compatibility with Nitrogen Trifluoride (NF3)
Newton, B.E., Chiffoleau, G.J.A.; "Materials Compatibility with Nitrogen Triflouride (NF3)," J. ASTM Intl., Vol. 3, No. 5, ASTM International, West Conshohocken, PA, 2006, Paper ID JAI13552.
KEYWORDS: Nitrogen trifluoride (NF3), promoted combustion, oxygen index, autogenous ignition temperature
ABSTRACT: Nitrogen trifluoride (NF3) is a widely used electronic specialty gas and is considered about 1.5 times more oxidizing than gaseous oxygen. A recent test program was sponsored by seven companies that are heavily involved in the worldwide industrial distribution and use of NF3 to develop several test systems and materials compatibility data for the most common metals and nonmetals utilized in NF3 transfer systems. This paper presents the data developed by the industry steering group on the compatibility of 12 metallic materials and 15 nonmetallic materials with NF3. The flammability of metallic materials were evaluated by their promoted combustion threshold pressure and the nonmetallic materials were evaluated by their autogenous ignition temperature (AIT) and NF3-index for sustained combustion.
Mechanical Impact of Aluminum Alloy Gas Cylinder Pressurized with Oxygen
Chiffoleau, G.J.A., Newton, B.E., Holroyd, N.J.H., Havercroft, S.; "Mechanical Impact of Alumninum Alloy Gas Cylinder Pressurized with Oxygen," J. ASTM Intl., Vol. 3, No. 5, ASTM International, West Conshohocken, PA, 2006, Paper ID JAI13534.
KEYWORDS: mechanical impact, aluminum cylinders, ignition
ABSTRACT: Over the past 30 years a handful of fires in medical oxygen high pressure gas storage systems involving aluminum alloy cylinders have been deemed to be associated with mechanical impact-induced ignition of a contaminated system. For example, hydrocarbon contamination and mechanical impact promoted by being dropped during transportation. While the number of these incidents is minuscule compared to the number of systems used in the field, the effect is significant when such an ignition occurs. The kindling chain and initial ignition point of these fires, however, is poorly understood. Although made from more oxygen compatible metallic materials, the cylinder valves attached to these aluminum cylinders contain nonmetallic materials and are in direct contact with the cylinder threads, which are the thinnest cross section of the cylinder. A mechanical impact test was developed to investigate the conditions required to cause ignition of a cylinder and valve assembly by this ignition mechanism, with and without a wide range of controlled contaminants. Specially prepared small cylinders were assembled with commonly used brass cylinder valves and positioned under a drop tower capable of delivering energies up to 434 J (320 ft·lb). Cylinder assemblies were tested with various orientation and impact points including the cylinder valves and no ignitions were recorded in a total of 23 tests.
Analysis Tools Used to Evaluate Oxygen Hazards and the Oxygen Compatibility of Metals
Forsyth, E.T., Newton, B.E., Chiffoleau, G.; "Analysis Tools Used to Evaluate Oxygen Hazards and the Oxygen Compatibility of Metals," J. ASTM Intl., Vol. 3, No. 5, ASTM International, West Conshohocken, PA, 2006, Paper ID JAI13540
KEYWORDS: oxygen, hazards analysis, metals, compatibility, ignition mechanism, fire, Computational Fluid Dynamics (CFD), flammability, evaluation, materials selection
ABSTRACT: Performing analyses of the fire hazards in oxygen systems is critical to avoiding fires. Over the years, several systematic approaches to analyzing fire hazards in oxygen systems have been proposed and analysis methodologies for oxygen systems have become more refined. Specific evaluation is performed on the compatibility of materials of construction, the presence of ignition mechanisms, and the effects that ignition or a fire would have on the component, system, and personnel. The authors of this paper routinely perform hazards analyses and failure analyses of oxygen systems for their clients and have applied new engineering technologies and materials test data to better understand, discern, and characterize oxygen fire hazards. This paper describes some of the new technologies and materials test data used and how they can be applied to evaluating the compatibility of metals in oxygen service, including three-dimensional component analysis; Computational Fluid Dynamics (CFD) flow modeling; metals flammability test data in static, flowing, and high-temperature oxygen; and metals ignition test data.
Waller, J. M., Newton, B. E., and Beeson, H. D., "Effect of Molding and Machining on Neoflon CTFE M400H Polychlorotrifluoroethylene Rod Stock and Valve Seat Properties," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Tenth Volume, ASTM STP 1454, T. A. Steinberg, H. D. Beeson, and B. E. Newton, Eds., ASTM International, West Conshohocken, PA, 2003.
KEYWORDS: PCTFE, Kel-F, Neoflon, valve seats, molding, machining, annealing, dimensional stability, molecular weight, crystallinity, material specifications
ABSTRACT: The effect of processing and machining on the dimensional stability of polychlorotrifluoroethylene (PCTFE) rod stock and oxygen gas cylinder valve seats was investigated. Initial testing focused on two types of extruded rod stock and one type of compression-molded rod stock made from the same lot of Neoflon® CTFE M400H.4 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 made from the above types of rod stock were tested. Property changes caused by processing and machining were evaluated using thermomechanical analysis (TMA), specific gravity, differential scanning calorimetry, zero strength time, and intrinsic viscosity. The dimensional stability of valve seats as revealed by TMA tended to be more dispersed and grouped by manufacturer and did not overlap rod stock TMA data, suggesting that machining had an important effect on seat properties. These and other findings are discussed in the context of process history, annealing, percent crystallinity and molecular weight. Structure-property characteristics of emulsion-polymerized Kel-F® 815 and suspension-polymerized Neoflon M400H PCTFE are compared, and the merits of current PCTFE specifications evaluated.
Oxygen Fire Cause and Origin Analysis of the CUMA V2 Underwater Breathing Apparatus
Forsyth, E. T., Eaton, D. J., and Newton, B. E., "Oxygen Fire Cause and Origin Analysis of the CUMA V2 Underwater Breathing Apparatus," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Tenth Volume, ASTM STP 1454, T. A. Steinberg, H. D. Beeson, and B. E. Newton, Eds., ASTM International, West Conshohocken, PA, 2003.
KEYWORDS: fire investigation, oxygen, SCUBA, ignition mechanisms, cause and origin analysis
ABSTRACT: The Canadian Underwater Mine-countermeasures Apparatus (CUMA) is a self-contained, semi-closed circuit underwater breathing apparatus used by the Canadian Forces for underwater mine search, investigation, and disposal. On November 30, 2001, the Experimental Diving Unit staff at Defence Research and Development Canada - Toronto was preparing for an experimental dive using the CUMA Version 2 (V2) in their facility's hyperbaric chamber. A fire occurred in the CUMA V2 as the Team Leader (diver wearing the CUMA V2) opened the oxygen sphere valve. The fire was severe, ejecting fire and molten metal for a distance of approximately 7 feet from the diver's back-mounted unit, and lasting for an extended duration before the diver's teammates were able to remove the backpack and extinguish the fire. No one was seriously injured in the incident. Wendell Hull & Associates, Inc. (WHA) was contracted to investigate the oxygen fire, specifically to perform a cause and origin analysis, and to provide recommendations for the CUMA V2 oxygen system to improve its ignition resistance and fire tolerance. WHA reviewed the incident details, system components, materials of construction, and operational procedures and conditions. WHA also inspected the burned hardware and disassembled individual components as required to characterize the burn and melt-flow patterns. Key materials were sampled as required and chemical analyses on samples were done to obtain positive material identification. The evidence is consistent with the local origin of the fire being within the first-stage regulator close to the non-metal seat. The evidence also indicates that operationally induced ignition mechanisms and incompatible materials were causative factors in the ignition and propagation of the fire. This paper describes the events of the oxygen fire incident, the protocol used to analyze the fire's cause and origin, and the results of the analysis. The recommendations to improve CUMA V2's ignition resistance and fire tolerance are also discussed.
Cause And Origin Analyses Of Two Large Industrial Oxygen Valve Fires
Newton, B. E., and Forsyth, E. T., "Cause And Origin Analyses Of Two Large Industrial Oxygen Valve Fires," Flammability and Sensitivity of Materials in Oxygen- Enriched Atmospheres: Tenth Volume, ASTM STP 1454, T. A. Steinberg, H. D. Beeson, and B. E. Newton, Eds., ASTM International, West Conshohocken, PA, 2003.
KEYWORDS: fire investigation, failure analysis, oxygen fire, cause and origin analysis, pipeline fires, root cause analysis
ABSTRACT: Two recent fires were investigated in industrial gas oxygen delivery systems that resulted in significant facility damage as well as personnel injury and death. One fire developed in a 6-in. ball valve being utilized as an isolation valve. This fire was kindled while the valve was being opened under a low pressure differential and resulted in extensive burnout and significant facility destruction. The other fire developed in a 12-in. butterfly valve being utilized as a pipeline isolation and pressurization control valve downstream of an oxygen boost compressor. The valve utilized generally good materials but was vulnerable to ignition and sustained propagation probably due to the presence of an unusual kindling chain. This paper reviews the investigations and analytical work performed during the accident reconstructions and highlights the "lessons learned" from the incidents.
Forsyth, E. T., Newton, B. E., Rantala, J., and Hirschfeld, T., "Using ASTM Standard Guide G 88 to Identify and Rank System-Level Hazards in Large-Scale Oxygen Systems," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Tenth Volume, ASTM STP 1454, T. A. Steinberg, H. D. Beeson, and B. E. Newton, Eds., ASTM International, West Conshohocken, PA, 2003.
KEYWORDS: oxygen hazards, hazards analysis, risk management, ignition mechanisms, fire risk analysis
ABSTRACT: Performing hazards analyses and fire risk assessments on oxygen systems is critical to ensure that a system design has a low probability of ignition and a low consequence of ignition. Historically several different methods have been used to identify and evaluate fire hazards in oxygen systems. Most of these methods, however, are designed for detailed materials or component analyses, and can be impractical for large-scale oxygen systems with many components and even multiple end processes. Wendell Hull & Associates, Inc. (WHA), in conjunction with Oxygen Safety Consultants, Inc. and INCO Ltd., has developed an efficient approach to identify and evaluate hazards in large-scale oxygen systems. The WHA oxygen hazards and fire risk assessment process considers the important aspects of oxygen system safety as they relate to design, cleaning, operations and maintenance, and uses ASTM Standard Guide G 88 as a basis for quickly identifying and ranking system-level oxygen hazards. ASTM G 88 is a standard guide for oxygen system design containing many system-level factors known to contribute to ignition and propagation of fires. The WHA analysis process applies ASTM G 88 at the system level, using both schematic analysis and visual inspection to systematically assign a hazard severity ranking to all system components, allowing components that possess the greatest risk of ignition and fire propagation to be quickly identified and further evaluated. This paper describes the WHA oxygen hazards and risk assessment method, using ASTM G 88 to quickly identify and assign a hazards severity ranking to components in large-scale oxygen systems.
Failure Investigation of a Welding Regulator Fire
Newton, B. E., Hull, W. C., and Beeson, H., "Failure Investigation of a Welding Regulator Fire," Flammability and Sensitivity of Materials in Oxygen- Enriched Atmospheres: Ninth Volume, ASTM STP 1395, T. A. Steinberg, B. E. Newton, and H. D. Beeson, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000.
KEYWORDS: regulator burnout, regulator explosion, regulator fire, welding regulator, oxygen fire
ABSTRACT: This paper describes the investigation and failure analysis of a welding regulator fire that resulted in explosive energy release and injury to an operator. The failure analysis revealed that an organic contaminant in the form of an insect had entered the cylinder valve prior to attachment of the regulator. Ignition of the insect and nest materials led to an explosion-like overpressure that blew the high-pressure poppet through the nozzle and forcibly separated the regulator bonnet from the main body. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) on the residue from the fire-damaged components confirmed that insect nest material was present at the time of the fire. Autogenous Ignition Testing (AIT) on similar insect debris revealed a very low ignition temperature and probable high heat of combustion. The explosion-like energy release was felt to be related to a momentary containment of the fire in the early stages of the combustion event which led to greater involvement of the cylinder valve's nylon seat and resulted in increased reaction kinetics.
Failure Analysis of Aluminum-Bodied Medical Regulators
Newton, B. E., Hull, W. C., and Stradling, J. S., "Failure Analysis of Aluminum-Bodied Medical Regulators," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Ninth Volume, ASTM STP 1395, T. A. Steinberg, B. E. Newton, and H. D. Beeson, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000.
KEYWORDS: regulator burnout, regulator explosion, regulator fire, welding regulator, oxygen fire, aluminum regulator fire, aluminum combustion, explosive energy release
ABSTRACT: Over the past 5 years 16 fires have been reported to the FDA involving aluminum-bodied medical regulators. These incidents are reported to have caused severe burns to 11 health care workers and patients. Many of the incidents have occurred during emergency medical use or during routine equipment checkouts. This paper summarizes the investigation and failure analysis of several of these fires and provides the cause and origin analysis for each. Ignition with catastrophic burnout of the regulator has been observed in each of these cases. The active ignition mechanisms are felt to have included particle impact in some cases, contaminant promoted ignition in other cases, and adiabatic compression in at least one other. Several of the fires are believed to have been caused by particulate debris entrained in the oxygen flow stream from aluminum highpressure cylinders. The regulator design, pertaining to the exposure of aluminum to active ignition mechanisms, and the use of aluminum cylinders with aluminum regulators are discussed.
Potential Ignition Mechanism of Buna-N O-Rings in Liquid-Oxygen
Newton, B. E., Wilson, D. B., and Stradling, J. S., "Potential Ignition Mechanism of Buna-N O-Rings in Liquid-Oxygen," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Ninth Volume, ASTM STP 1395, T. A. Steinberg, B. E. Newton, and H. D. Beeson, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000.
KEYWORDS: Buna-N O-rings, liquid-oxygen, failure analysis, elastomer ignition, mechanical impact
ABSTRACT: Buna-N O-rings used in liquid-oxygen dewars have been implicated in fires when subjected to a shearing load. Such a loading occurs when the dewar flange receives a mechanical impact due to the dewar falling over. The ignition event has been replicated under controlled conditions but only when the O-ring has been previously distorted such as could occur during improper seating of the seal in the upper flange, or when forced extrusion of the seal occurs while exposed to liquid-oxygen. This paper applies an ignition model to the experimental system to extend the parameterization of oxygen pressure/temperature to the extent of O-ring damage, shear energy and oxygen flow. The model allows for heat loss and variable generation rates.
Waller, J. M., Newton, B. E., Beeson, H. D., and Haas, J. P., "Comparison of the Dimensional Stability of Kel-F 81 and Neoflon CTFE M400H Polychlorotrifluoroethylenes Used in Valve Seat Applications," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Ninth Volume, ASTM STP1395, T. A. Steinberg, B. E. Newton, and H. D. Beeson, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000.
KEYWORDS: PCTFE, Kel-F, Neoflon, valve seats, dimensional instability, impact sensitivity, glass transition, flow friction
ABSTRACT: The dimensional stability of polychlorotrifluoroethylene (PCTFE) valve seats used in gas cylinder regulator applications was evaluated by thermomechanical analysis (TMA). Testing focused on two commercial grades of PCTFE, Kel-F®4 81 and Neoflon®4 CTFE M400H, and on actual PCTFE valve seats obtained from different manufacturers. The effects of resin grade, percent crystallinity, and process history on TMA deflection were evaluated. TMA results frequently showed low-temperature dimensional instability between 40 and 70 °C. The corresponding permanent height change resulting from brief cyclic heating of as-received material to 150 °C ranged from to +3.9 to -8.5 percent. Complementary differential scanning calorimetry data indicated the origin of the dimensional instability to be anomalous relaxation at or close to the glass transition. The data are discussed in the context of several proposed valve seat failure mechanisms: contaminant promotion, flow resonance, and flow friction. The combined data show significant property variations within the PCTFE resin family. Such property variations could have important implications for the use of PCTFE in valve seat applications.
A Database for Metallic and Nonmetallic Materials Commonly Utilized in Oxygen Service
Newton, B., Hull, W.C., and Stradling, J., "A Database for Metallic and Nonmetallic Materials Commonly Utilized in Oxygen Service," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Eighth Volume, ASTM STP 1319, W.T. Royals, T.C. Chou, and T.A. Steinberg, Eds., American Society for Testing and Materials, 1997.
KEYWORDS: materials database, oxygen compatibility, relational database, hazards analysis, materials testing
ABSTRACT: This paper presents the design, structure, and use of a materials database for metallic and nonmetallic materials commonly utilized in oxygen service. Also discussed is the need for a widely accessible and easily searched database of materials compatibility test data for general use within the oxygen community. Over the last two decades, the ignition and combustion properties of metallic and nonmetallic materials exposed to oxygen-enriched environments have been widely studied by both government and commercial industry. However, to our knowledge, these data have never been compiled into a comprehensive and easily accessible database for general utilization and cross-comparison. Consequently, collecting the necessary data for hazards analyses on materials and components is difficult and time consuming, when done in accordance with the procedures advanced by ASTM Guide G-63, "Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service," and ASTM Guide G-94, "Standard Guide for Evaluating Metals for Oxygen Service." This paper presents a database of materials test data and discusses the utilization of these data in a computerized hazards analysis that generally follows the guidelines of ASTM G-63 and G-94 and the "good practices" of ASTM G-88. The relational structure of the database is presented and the advantages of this type of data structure are discussed.
A 6000 psig Gaseous Oxygen Impact Test System for Materials and Components Compatibility Evaluations
Newton, B., Porter, A., Hull, W.C., Stradling, J., and Miller, R., "A 6000 psig Gaseous Oxygen Impact Test System for Materials and Components Compatibility Evaluations," Flammability and Sensitivity of Materials in Oxygen- Enriched Atmospheres: Eighth Volume, ASTM STP 1319, W.T. Royals, T.C. Chou, and T.A. Steinberg, Eds., American Society for Testing and Materials, 1997.
KEYWORDS: oxygen compatibility, component testing, pneumatic impact, materials testing
ABSTRACT: Over the last several years, the International Standards Organization (ISO) has developed standards which require pneumatic impact testing on valves, regulators, and other oxygen components used in Europe in medical, industrial, and commercial applications. The several standards involved all reference a test system designed by BAM and presented in ASTM STP 1267 by Binder, et. al. in their paper "A 500 BAR Gaseous Oxygen Impact Test Apparatus For Burn-Out Testing Of Oxygen Equipment." This paper discusses another gaseous oxygen impact test system designed to conform to the IS0 standards, and presents its performance characteristics in pneumatic impact testing. This paper also discusses the value of a component test method and considers some of the critical parameters that should be maintained in order to produce consistent test results with different test systems.
Newton, B. E., Porter, A. R., Hull, W. C., Henry, S. H., Anderson, D. S., and Randall, L. N., "Case Study of an Oxygen-Acetylene Cutting Torch Failure and Measured Overpressures Due to Flashback Reactions," Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: 7th Volume, ASTM STP 1267. Dwight D. Janoff, William T. Royals and Mohan V. Gunaji, Eds., American Society for Testing and Materials, Philadelphia, 1995.
KEYWORDS: oxygen-acetylene combustion, flashback, oxygen cutting torch, welding equipment, oxygen, acetylene
ABSTRACT: A generalized case study of the failure of an oxygen-acetylene cutting torch is presented with discussion of the failure and investigation. The theory that an oxygen-acetylene flashback reaction caused the explosive failure of the torch mixing tube was investigated. The investigation led to the conclusion that abusive treatment of the torch was the primary cause of the failure. The mechanical strength of the cutting torch was determined and the dynamic overpressures due to oxygen-acetylene flashback reactions were measured by means of fast-response piezoelectric pressure transducers. The dynamic pressure measurements were compared and related to predictions of the NASA Gordon and McBride "Computer Program for Calculations of Complex Chemical Equilibrium Compositions, Rocket Performance, Incident and Reflected Shocks, and Chapman-Jouquet Detonations" for oxygen-acetylene combustion. Based on this investigation, a reconstruction of the accident is proposed.
Ignition of PTFE-Lined Flexible Hoses by Rapid Pressurization with Oxygen
Janoff, D., Bamford, L. J., Newton, B. E., and Bryan, C. J., "Ignition of PTFE-Lined Flexible Hoses by Rapid Pressurization with Oxygen", Svmposium on Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Fourth Volume, ASTM SPT 1040, Joel M. Stoltzfus, Frank J. Benz, and Jack S. Stradling editors, American Society for Testing and Materials, Philadelphia, 1989.
KEYWORDS: Ignition, PTFE, high-pressure oxygen, adiabatic compression, shock ionization
ABSTRACT: There has been increasing concern in recent years about the ignition sensitivity of polytetrafluoroethylene (PTFE) lined flexible hoses used in oxygen service. Stainless steel braided flexible hoses lined with PTFE were tested in a high-volume pneumatic-impact system. The objective of the testing was to characterize the ignition mechanism by determining the effects on ignition of impact pressure, pressurization rate, and volume upstream and downstream of the flexible hose. Ignitions occurred at impact pressures well below the working pressure of the hoses, and at pressurization rates that can easily be obtained with manually operated valves. The hoses ignited at the downstream end and combustion propagated back toward the source of fresh oxygen. The addition of stainless steel hardline downstream from the hose prevented ignitions at all pressures and pressurization rates. Internal observations revealed evidence of shock ionization of the oxygen prior to ignition. Although adiabatic compression of the oxygen is the most likely source of thermal energy for ignition, shock ionization of the oxygen may play an important role in the ignition mechanism by decreasing the activation energy necessary to kindle the reaction.
Promoted Ignition of Oxygen Regulators
Newton, B. E., Langford, R. K., Meyer, G. R., "Promoted Ignition of Oxygen Regulators", Symposium on Flammability and Sensitivity of Materials in Oxvqen Enriched Atmospheres: Fourth Volume, ASTM STP 1040, Joel M. Stoltzfus, Frank J. Benz, and Jack S. Stradling editors, American Society for Testing and Materials, Philadelphia, 1989.
KEYWORDS: oxygen regulator fire, oxygen regulator burnout, regulator contamination, regulator ignition, ignition containment, oxygen fires, oxygen hazards, oxygen safety "Oxygen Regulator Fire" (ORF) and "Oxygen Regulator Burnout" (ORB) are terms that are well known in the commercial gas industry.
ABSTRACT: The ignition containment capability of 12 oxygen regulators subjected to promoted ignition was investigated. Oxygen regulators were contaminated with hydrocarbon oil to levels ranging from 98 mg to 651 mg. The regulators were preset to 0.55 MPa (80 psi) and interfaced to a system which permitted a flow rate of 1966 cc/s (250 scfh). The regulator inlets were then pressurized to 15.2 MPa (2200 psi) with gaseous oxygen and the oil was ignited by an electrical ark located upstream of the test article inlet port. The hydrocarbon flame was allowed to propagate with the oxygen flow throughout the regulator internal cavities. The test articles were monitored by video to document their ability to contain the hydrocarbon promoted internal combustion. Reactions ranged from complete containment of the promoted ignition for one two-stage regulator to extensive burning and explosive energy release for several other single-stage and two-stage regulators. The results suggest the overwhelming need to prevent the introduction of hydrocarbon oil in regulators and other oxygen components.
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