Download or read book Ignition of Contaminated Aluminum by Impact in Liquid Oxygen Influence of Oxygen Purity written by Etienne Werlen and published by . This book was released on 2009 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impact tests in liquid oxygen and oxygen enriched liquids have been conducted on aluminum foils (0.2 mm thick) used for heat exchangers of air separation units (ASUs). Some adaptations to the ASTM Standard D2512, "Standard Test Method for Compatibility of Materials with Liquid Oxygen," have been done to ensure the good control of oxygen content in the cryogenic liquid and to get reproducible results in aluminum ignition with hydrocarbon coating. Modified striker pins with a cavity on the contact surface have been used. The vertical guiding and the centering of the striker pins have been ensured by using two machined guides. Test samples were three layers of aluminum foil, two corrugated and one flat, contaminated by various quantities of hexadecane. The criteria for the identification of aluminum ignition (positive tests) have been validated by performing Scanning electron microscope surface analysis on residuals of a few impact tests performed in copper cups. Criteria have also been defined to check that hexadecane combustion took place in negative tests. A sufficient number of tests have been performed to plot the probability of ignition of the aluminum samples as a function of the average thickness of hexadecane coating and as a function of the oxygen content in the cryogenic liquid varying from 50 % to above 99.95 %. The remaining part in the cryogenic liquid was nitrogen and 2.3 % argon except for one series of tests where the influence of the absence of argon could be identified. The results of these tests can be used to assess the risk of ignition of some aluminum exchangers or structures used in ASU.
Download or read book Ignition of Aluminum by Impact in LOX Influence of Contaminants written by D. Roy and published by . This book was released on 2000 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Impact tests in LOX according to ASTM D 2512 were conducted on thin aluminum films (7 to 20 ?m) together with glass fibers films used for the super insulation of vacuum insulated cryogenic vessels. Influence of the film thickness, type of material and number of layers were investigated. Practical information is given concerning the requirements for such insulation.
Download or read book Flammability and Sensitivity of Materials in Oxygen enriched Atmospheres written by Dennis W. Schroll and published by ASTM International. This book was released on 1988 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceeding held at Churchill College, Cambridge, England, April 1987. A reference for both the skilled and the uninitiated in the concepts and practices for the design and maintenance of all types of oxygen systems. Cov five areas: ignition of metals, nonmetal ignition, material selection for oxygen.
Download or read book Ignition Phenomena of Bulk Aluminum Alloy as a Function of Oxygen Pressure written by K. Nguyen and published by . This book was released on 1984 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was undertaken to investigate the ignition phenomena of 6061 aluminum alloy as a function of oxygen pressure. Cylindrical aluminum alloy specimens were ignited in a pure oxygen environment by a focused cw CO2 laser beam. To study the effect of oxygen pressure on the surface temperature at ignition of 6061 aluminum alloy, the experiments were conducted at oxygen pressures ranging from 0.084 to 2.413 MPa. The temperature history of the entire upper surface of the specimen and of a 0.5 mm diameter spot located initially at the center of the specimen top surface was recorded by using a commercial two-color ratio pyrometer and a fast-response, narrow-band, two-color pyrometer. Mass, brightness, and interior temperatures, for certain experiments were also recorded throughout the experiment. The results show that the surface temperatures at ignition of the alloy obtained from the temperature curves are below the melting temperature of the aluminum oxide and are slightly dependent on oxygen pressure. The data indicate that the ignition mechanism is complex and probably composed of several phenomena acting both separately and in conjunction with each other.
Download or read book Ignition Testing by Fracture of Oil and Particle Contaminated Aluminum Pipes in High Pressure Oxygen at Ambient and Elevated Temperature written by Matthias Meilinger and published by . This book was released on 2012 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum and its alloys are the preferred material in air separation units (ASUs) and are submitted to strict cleanliness requirements to avoid combustion reactions in oxygen. Linde Engineering Division has investigated the role of particle contamination for the ignition of aluminum pipes in high pressure oxygen. Tests were carried out with oil coated aluminum pipes in combination with a particle contamination. Accumulations of following particle types were tested: molecular sieve 13X, filter deposits (rust), perlite, quartz sand, and aluminum swarf. The contaminated pipes were pressurized with oxygen up to 150 bar and fractured in a hydraulic apparatus. The conditions and probability of an ignition reaction compared with oiled pipes without particles were of interest. Additionally, similar high pressure tests with a mixture of liquid and gaseous oxygen were performed. A combination of oil and particles enhanced the probability of an ignition at elevated temperatures. The results indicated that temperature is the dominating factor for an oil ignition, not the oxygen pressure. At room temperature, an oil/aluminum ignition could never be initiated. The results give a good understanding regarding the mechanism of an aluminum ignition and help to clarify causes of damage in the ASU industry.
Download or read book Flammability and Sensitivity of Materials in Oxygen enriched Atmospheres written by B. E. Newton and published by ASTM International. This book was released on 2003 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Pressure Dependence of Aluminum Ignition in Gaseous Oxygen and Possible Ignition Mechanisms in Brazed Aluminum Heat Exchangers written by Etienne Werlen and published by . This book was released on 2012 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ignition of aluminum foils in gaseous oxygen was experimentally tested using a diode laser as the energy source, which provided a well-controlled, accurate, and reproducible method of ignition. The tests were conducted under different conditions in terms of oxygen pressure, oxygen purity, aluminum thickness, and gas velocity. The aluminum foils tested were between 0.2 mm and 0.45 mm thick, a range typical of fins contained in brazed aluminum heat exchangers (BAHXs) used in air separation units (ASUs). The experimental apparatus was composed of a pressure vessel in which a single aluminum test sample was placed. The vessel contained an optical window that allowed a short laser pulse of known power to be applied to the aluminum sample. The energy dose was systematically varied in order to identify the threshold ignition energy, defined as the point at which the probability of aluminum combustion with propagation beyond the laser spot was 50 %. The experimental results show that O2 pressure has no significant effect on the ignition energy of aluminum over the pressure range tested (10 bar to 120 bar). This conclusion holds for both standard commercial grade purity O2 (99.8 %) and high purity O2 (99.99 %), as well as for gas velocities higher than typically encountered in ASU BAHXs. Heat conduction calculations indicate that aluminum ignition occurs when the laser spot temperature reaches the melting point of the passivating oxide layer (about 2200 K to 2300 K). The heat conduction model accurately explains the dependence of the ignition energy on the aluminum sample thickness. These test results have been used in assessing the risk of ignition of BAHXs used in high pressure oxygen service in ASUs.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Surface Ignition of Aluminum in Oxygen written by B. Newton and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published reports of burning aluminum in oxygen using ASTM G 124-type testing demonstrated that aluminum alloys are difficult to ignite but once ignited are extremely flammable in terms of regression rate and energy release. The ignition resistance of aluminum is associated with its tenacious and protective oxide, which allows aluminum to safely contain high-pressure oxygen in certain applications. The ignitability of aluminum varies between alloys and surface treatments so a test method was developed to evaluate the ignitability of various aluminum surfaces. The test method uses a promoted ignition chamber consistent with ASTM G 124 testing; however, the test sample is configured in the shape of a coupon. Instead of promoting the sample with an electrically heated wire, a controlled electrical arc is generated by drawing an electrode away from the center of the coupon while passing current through the sample. The level of energy applied to the surface of the coupon is semi-quantifiable and kept constant between tests. Based on this semi-quantifiable amount of energy, an ignition pressure is established and the influence of alloy composition and surface treatments on aluminum is evaluated.
Download or read book NASA Scientific and Technical Reports written by United States. National Aeronautics and Space Administration Scientific and Technical Information Division and published by . This book was released on 1966 with total page 1440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ignition of Contaminants by Impact of High Pressure Oxygen written by L. Bamford and published by . This book was released on 1988 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ignition of hydrocarbon-based oil films by the impact of high-pressure oxygen has been studied as part of an evaluation of cleanliness requirements for oxygen systems. Stainless steel lines contaminated on the inside surface with known quantities of oil were closed at one end, attached to a high-pressure (52 MPa) oxygen system, and pressurized by opening a high-speed valve. Ignition of the oil films was detected by a photocell attached to the closed end of the line.
Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1991 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sealed Aluminum Cavity Reactions When Submerged in Pure O2 Reboiler Sump written by Stephen J. Wieder and published by . This book was released on 2009 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aluminum has a long history of safe service in cryogenic air separation units; however, there have been some rare instances of aluminum/O2 reactions. Aluminum ignition and propagation depends strongly on the oxygen purity, oxygen pressure, aluminum geometry, and type and energy of igniter. Over the years, the industry has experienced a particular type of aluminum/O2 reaction: cavity incidents. These incidents are characterized by the presence of a sealed cavity that is created when welding two metal items together. Such a sealed cavity can lead to aluminum ignition under certain specific conditions: (1) The sealed cavity is submerged in a bath of liquid oxygen. Over a long period of time, liquid cryogen can enter the sealed cavity through slight imperfections in the weld. (2) The sealed cavity is warmed over a short period of time, typically a few hours. (3) The liquid oxygen vaporizes, and the pressure inside the cavity builds to very high levels (potentially over 50 bars). (4) Ignition occurs in the high pressure, high purity oxygen environment, and the resulting aluminum/oxygen reaction burns through the relatively thick cavity walls. (5) The oxygen and reaction products exit the cavity through the hole, lowering the pressure and extinguishing the reaction. This paper discusses two such incidents, which have occurred since 2001. Both incidents took place in brazed aluminum heat exchanger (BAHX) reboiler support beam systems. In both cases, the BAHX reboiler was damaged, leading to a process leak, which required that the plant be repaired. In one case, the damage occurred while warming a plant. In the second case, the damage occurred during normal operation. This second case does not appear to follow the sequence of events outlined above; however, evidence is presented to support the scenario that the cavity incident occurred during a previous warming of the plant. This initial damage then impaired the normal operation of the reboiler, leading to a second hydrocarbon related reaction during normal operation. The paper discusses the potential ignition mechanisms, probable causes of the incidents, and methods to prevent future re-occurrences.
Download or read book Flammability and Sensitivity written by and published by ASTM International. This book was released on with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 1256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flame Spreading and Violent Energy Release VER Processes of Aluminum Tubing in Liquid and Gaseous Oxygen Environments written by JH. Sturges and published by . This book was released on 2000 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is motivated by the need for a fundamental understanding of the unintentional combustion of aluminum heat exchange equipment used in liquid oxygen (LOX) service; in which combustion can be quite energetic and cause severe damage. The promoted ignition, flame spreading, and combustion phenomena of aluminum tubing filled with LOX, surrounded by a shell of gaseous oxygen (GOX), were systematically observed and recorded. Parameters studied include the tube- and shell-side pressures, GOX and LOX flow rates, and GOX quality (the mass fraction of GOX in the two-phase flow inside the tube sample). Results from high-speed movie films indicate that under certain operating conditions, a transition from a "normal" (much slower) burning mode to an extremely rapid and violent burning mode occurs. This transition was shown to occur in some cases after a period of delay and in other cases immediately after the onset of ignition. The "Violent Energy Release," or VER burning mode, is characterized by an extremely high flame spreading rate (1-2 orders of magnitude higher than the flame propagation rate in a purely GOX environment), a high luminosity flame-zone, and a very rapid rate of heat release. Within the range of initial conditions tested, the major parameters that tend to enhance the degree of violence of aluminum combustion in a LOX/GOX environment include increasing initial pressure and decreasing GOX quality (higher LOX fraction). A burning regime map showing the threshold boundaries between conditions of no self-sustained flame propagation, "normal" burning, and VER burning mode is presented. It was found that the threshold boundaries between the different regimes of burning are essentially determined by the tube-side conditions. In addition a detailed insight into the controlling mechanisms of the VER reaction has been obtained, and a physical description of the transition mechanism is presented.
Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1042 pages. Available in PDF, EPUB and Kindle. Book excerpt:
