Fire Science and Technology

Science

Calcination Temperature Effects to CO-Gas Sensor of Pt-Dispersed Hydrous SnO₂ Gel

Takashi Handa, Hiroshi Fukaya, Osami Sugawa, Yoshinori Terasawa, Koich ...

1983 Volume 3 Issue 1 Pages 1-12
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.1

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A CO gas sensor which works at room temperature without an inner heater has been investigated. The sensing material is ceramics made from hydrous SnO₂ gel with Pt dispersion. The effect of calcination in the range from room temperature to 1100°C was studied. The increment of crystallite size of SnO₂ started from the calcination temperature of 400°C, and increment of its size was lowered by Pt dispersion. The crystallite size of Pt increased in the range from 650°C to 800°C and leveled off above 800°C. The specific surface area of Pt-dispersed hydrous SnO₂ gel was larger than that of hydrous SnO₂ gel without Pt. The relation between current (I) and voltage (V) was found to be I = KVα. The value of α was larger than 1 for calcination temperature below 650°C for Pt-dispersed hydrous SnO₂ gel, and at 450°C the value of α showed a maximum. The conductance of Pt-dispersed hydrous SnO₂ gel was less than that of hydrous SnO₂ gel without Pt. The ceramic with Pt/Sn = 4.4 mole% calcined at 450°C gave the best response to CO gas.

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Computer Simulation of the Spontaneous Combustion of Coal Storage

Takashi Handa, Masahiro Morita, Osami Sugawa, Tadahiro Ishii, Kenji Ha ...

1983 Volume 3 Issue 1 Pages 13-23
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.13

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The two-dimensional govering equations including an exothermic chemical reaction, a heat convection a buoyancy effect and a diffusion for the spontaneous combustion of coal storage are derived from the thermophysical and thermochemical considerations. The oxidative pyrolysis of coal is assumed to be represented by a two-step chemical reaction. These governing equations are approximated by using the difference equations of Crank and Nicholson's implicit finite-difference method, and are solved numerically by the computer. The spontaneous combustion time of coal storage is predicted by the calculated results. Furthermore, the lowest spontaneous combustion time of coal storage is also calculated numerically on the adiabatic condition.

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Flame Reterdation Mechanism of Polypropyrenes & Phenolic Laminates

Naofumi Ebihara, Takashi Handa, Hirochika Yamamoto, Toshiaki Nagashima

1983 Volume 3 Issue 1 Pages 25-33
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.25

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This paper shows results obtained from investigating the correlation between combustion parameter and HBr flux density, to explain the difference in flame retardation mechanisms between flame retardant polypropylene and flame retardant phenolic laminate. The combustion parameter, the dominating factor in high molecular materials flame retardation at the time of an actual fire, was thought out from the standpoint of thermal decomposition behaviors for high molecular materials. In this paper, weight-loss rate, combustion efficiency, CO and CO₂ generation rate, heat generation rate, heat evolution efficiency was taken up as the combustion parameter. It was clarified that HBr could mainly suppress the thermal decomposition reaction of resin in the flame retardant polypropylene, while it could suppress the exothermic reaction through the oxidation decomposition of thermal decomposition products in the flame retardant phenolic laminate. In regard to the HBr effect on oxidation reactions, it was found that HBr could mainly suppress the oxidation reaction (C + O₂ → CO) in the flame retardant polypropylene, while it could mainly suppress the oxidation reaction (CO + O₂ → CO₂) in the flame retardant phenolic laminate.

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Flammability of Wood and Flame-Retarded Wood

Takashi Handa, Yoshinori Hashizume, Shuji Yoshizawa

1983 Volume 3 Issue 1 Pages 35-44
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.35

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The effects of phenol resin and fire retardants (NH₄Br and (NH₄)₂-HPO₄) on the smoldering combustion of wood have been investigated by the measurements of TGA, the dynamic viscoelasticity (E' and E") and the oxygen consumption.
The addition of fire retardants to wood accelerates the oxygen consumption of wood from 180°C corresponding to the weight loss and the decrease of E' and E". The solid residue of fire retardants-wood was remained more than that of wood at around 260°C. These results indicate that fire retardants increase the oxygen absorbable sites of wood which promote the evolution of gaseous components during thermal oxidation and result in the carbonization of wood.
Phenol-WPC system showed a long induction period of oxygen consumption at 200°C, irrespective of larger amount of oxygen consumption than that of wood. After 8hr-exposure to oxygen atmosphere, the weight of phenol-WPC decreases to the half value of the initial weight up to 200°C, however, the residual weight didn't change so much above 200°C. It is mentioned that the formation of cross-linking networks of phenol resin in the surface of the cell wall prevents the adsorption of oxygen into wood, and promotes the carbonization of wood at the temperature range above 200°C.

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Technology

Experimental Study on Thermal Stress within Steel-Frames

Noriyuki Ooyanagi, Masayuki Hirota, Kenichi Nakamura, Kunio Kawagoe

1983 Volume 3 Issue 1 Pages 45-55
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.45

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About 16 experiments were made with model steel-frames of three stories in which one or two girders were heated in constant heating rate by electric furnace. These experiments made it possible to analyze thermal stress within the steel-frames. It can be summarized that large thermal stress appeared in the frame corresponding to binding modulus of the frame. In some cases, the bucklings of heated girders were occurred. When heated girder didn't buckle, yield parts sometimes appeared in the non-heated columns which restrained expansion of it.

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Using the Harvard Fire Simulation

John A. Rockett, Masahiro Morita, Takashi Handa

1983 Volume 3 Issue 1 Pages 57-62
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.57

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Use of the Harvard Fire Simulation during the winter and spring of 1982 for the modelling of some Japanese fire situations was summarized for the May 1982 meeting of the Joint United States-Japan Panel on Fire Research. This paper is based on that summary.
Enrichments to the "official" level V version of the Harvard fire simulation are discussed. These included interlayer mixing in the vicinity of vents and its effect on the room heat balance, and the inclusion of a wall burning algorithm as an option of the simulation. With these additions, the Harvard V model more closely simulates important phenomena in a burning room in the later stages of fire growth.

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Some Examples of Application of Harvard V Fire Computer Code to Fire Investigation

Takashi Handa, Masahiro Morita, John A. Rockett, Osami Sugawa, Kenji H ...

1983 Volume 3 Issue 1 Pages 63-72
Published: 1983
Released on J-STAGE: September 16, 2009

DOIhttps://doi.org/10.3210/fst.3.63

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