Abstract of Special Research Report (SRR-No.12)
National Institute of Occupational Safety and Health, Japan
Study on Prevention of Explosions and Fires caused by New Materials
Introduction
SRR-No.12-1 |
Shigeru MORISAKI |
: With the rapid progress of science and technology such as material science and processing technology, the research and developments on new materials have been increasingly active in recent years. In connection with this, the commodities using these functional new materials have widely been spread even in our livelihood.
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Explosion Characteristics of Arsine,Silane and Phoshine in Air
SRR-No.12-2 |
Toshihiro HAYASHI |
: Highly explosible or toxic gases, such as semiconductor gases, introduced into high technology industries, have inevitably brought new types of accident into working sites. Yet no sufficient data are available on hazardous properties of those gases. This paper describes experimental explosion pressures and maximum pressure rise rates of arsine, silane and phosphine mixed with air. Experiments were also carried out on hydrogen and methane as reference gases. |
Explosive Reaction Rare Earth Elements with a Halogen-Containing Solvent
SRR-No.12-3 |
Takashi KOTOYORI and Takayuki ANDO |
: A group of elements which are composed of 17 elements and are all belonging to Group 3A, i.e. Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, are designated as the rare earth elements. |
Flammability Evaluation of Halogenatited Hydrocarbons such as Flon Substitutes
SRR-No.12-4 |
Hidenori MATSUI |
: Many kinds of halogenated hydrocarbons have been used in industries. Some of Hydrochloroflnorocarbons (HCFCs) or Hydrofluorocarbons (HFCs) such as HCFC-142b and HFC-134a have been newly developed as flon substitutes whose production is predicted to in crease in future. On the other hand, many Hydrochlorocarbons (HCCs) such as trichloroethylene have been used in large quantities. The use of these substances may be inhibited in industry from the stand point of environmental pollution protection. |
Ignition Hazard Evaluation of Metal Powders
SRR-No.12-5 |
Hidenori MATSUI |
: Newly developed solid materials have been used in advanced technology industries. For examples, rare earth metal such as ncodyniium-iron alloy is used for rare earth magnet, and amorphous silicon is used for solar cell. Great efforts have been put on developing new materials, but poor information about the safe handling has been presented in the production works.
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Dust Explosion Hazards of New Magnetic Materials
SRR-No.12-6 |
Toei MATSUDA |
: A dust explosion test facility has been constructed to give comparable data for rates of pressure rise with a standard 1 m3 chamber described in ISO 6184/1. The facility uses a 30 L spherical chamber, circumferentially flanged with a pneumatically raised upper hemisphere to allow easy cleaning between tests. It ran be used to measure lean and rich limits of explosibility, explosion pressure, rate of pressure rise and limiting oxygen concentration for an explosion. The test variables influencing the explosion parameters were examined. The time delay between the closing of the air injection valve and the activation of the chemical igniter is essential in determining the turbulence intensity of the mixture at ignition, and was fixed to 130 ms in the present tests. By use of the facility, the explosion characteristics of new magnetic material dust/air mixtures have been determined. The new magnetic materials tested were neodymium-iron-boron alloy (Nd2Fe14B), samarium-cobalt alloies (SmCo5, Sm2Co17), samarium-iron-nitrogen alloy (Sm2Fe14N3) and iron carbide fine powder. The test results are summarized in Table 1, showing relatively weak explosion severity with higher explosion sensitivity. The limiting oxygen concentrations were measured by diluting the dust/air mixtures with nitrogen. Some fine dust clouds were ignited spontaneously while dispersing with high pressure air, indicating that their limiting oxygen concentrations for an explosion were -- 0%. |
Dust Explosibility of Fine Ceramic Powders
SRR-No.12-7 |
Toei MATSUDA |
: The explosion characteristics of fine ceramic dust/air mixtures have been investigated experimentally. All tests were conducted at initial pressures of nominally 1.0 bar in a 30 L spherical explosion vessel. Fine ceramic powders of non-oxide compounds, which falls in four groups of carbides, nitrides, borides and silicides, were used. Average particle sizes of the dusts mostly lay between 1 and 10μm. The explosion parameters measured for each test were the lean limit of explosibility, the maximum explosion pressure and the maximum rate of pressure rise. The lean limit of explosibility was defined as the minimum concentration of dust in a cloud required to sustain the flame propagation, and obtained from the longest value of the time to a peak pressure, reflecting the slowest flame propagation from the ignition source to the vessel wall. |
Dust Explosion Hazards of Metallic Silicon
SRR-No.12-8 |
Toei MATSUDA |
: Silicon is an important element in view of engineering development of modern high technology, as it is extensively used hi industries of semi-conductor, organic silicon chemistry or fine ceramics. Fine metallic silicon powders, however, give rise to dust explosions. |
Evaluation of Dust Explosibility by a Testing Method
SRR-No.12-9 |
Toei MATSUDA and Hidenori MATSUI |
: Testing has been performed by a method for determining dust explosibility, which has been recently adopted by the Association of Powder Process Industry and Engineering in Japan. The test is conducted by a modified Hartmann tube apparatus and provides a measure of minimum explosible concentration, to which explosion violence is suggested to be related. The test results is shown in Table 1 and 2 for fine ceramic powders and carbon related dusts, respectively. The method allows a classification of the explosion violence as severe, moderate and weak according to the minimum explosive concentrations of lower than 100, 100 to 200, and larger than 200 g/m3, respectively. When a sample dust does not establish any self-sustaining flame in the tube at a concentration lower than 500 g/m3, the dust is regarded as non-explosible by the APPIE Method. However, the data acquired in the present tests show that lean limits of flammability for sonic dusts are more higher than 500 g/m3. Therefore, it should be tested up to more higher dust concentrations, and the other testing method using a large vessel with a powerful ignition should be applied, when a combustible dust is judged as non-explosible in the APPIE method. The test results are also compared with the explosion data obtained in a 30 L spherical test vessel with a chemical ignitor. |
A BAM Heat-Accumulation Storage Test on 1,2-naphthoquinone-2-diazido-5-sulfonyl chloride
SRR-No.12-10 |
Takashi KOTOYORI |
: To determine the temperature value representing the thermal stability of chemical substances such as exothermic onset temperature, thermal analysis using a relatively small quantity of sample is usually first employed. However, since the degree of thermal isolation increases with increasing the quantity of substance, the temperature value of this kind has a tendency to shift gradually to lower temperature side, as a larger quantity of substance is processed. Hence, it is frequently experienced that such a temperature value of a substance processed in the industrial scale is several tens lower than that found when a very small quantity is tested, as is the case in thermal analysis. Therefore, it becomes necessary to perform a thermal stability (or isothermal storage) test using a sample of considerable quantity, to establish the upper limiting temperature which must not be exceeded in temperature control for the chemical substance. |
Evaluation of Explosion and Fire Hazards in Manufacturing Process of Organic New Materials
SRR-No.12-11 |
Takayuki ANDO |
: In manufacturing, transporting, and storage of fine-chemicals such as Pharmaceuticals, functional resins, pesticides and so on, the hazard evaluations have been extremely important. These chemicals with enhanced value are usually produced in small quantity with a variety of processes. As a result, the same reaction vessel may often be used to synthesize different kinds of chemicals with different processes. Therefore, the potential hazards of the chemicals including raw materials, intermediates, and products may be increased due to unsuitable reaction condition, mistakes in plant operation, and so on. |