This paper describes an analytical approach to the evaluation of decreasing modes of average velocity, average excess temperature, and average gas concentration with distance along the full scale corridor based on the experimental data. Discharged mass flux and entrained mass flux through the free surface were estimated based on the gas concentration. The analogical relation was also estimated between the decreasing modes of average velocity and average excess temperature for corridor-direction.

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The conventional radiation tolerance criterion of people for the evacuation planning in city fire, taken for 2050kcal/m²h (2.38kW/m²), was determined after the wartime test, where are assumed some problems in radiation measurement.
This report aims at examining this criterion, and an attempt was made to measure the endured time of the subjects exposed opposite to radiation heating panel. The posture of the subjects was determined supposing that it would be most disadvantageous for people in big fire, and the endured time is defined here as the time until a subject gets away according to his own judgement. These test conditions are almost similar with those of the wartime test of Usui. As shown in Fig. 3, our test result indicates that the endured time of each subject for a radiation intensity is much longer than that of the wartime tests. However, regarding that the endured time generally drops very rapidly between about 1800kcal/m²h and 2300kcal/m²h, the radiation tolerance criterion as an engineering index for evacuation planning should be taken for a value safer than the conventional criterion.
The temperature of cheak surface of each subject was also measured with radiation thermometer, and it was found that the cheak surface temperature drops quite rapidly by the sweating on face. Though the pre-pain time of our tests agrees considerably well with those of the classical physiolosical studies by Buettner and Hardy, it was found that the endured time in our sense is much longer than the pre-pain time.

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The extinction limits of a small propan diffusion flame by usual dry powders were studied experimentally. The powder was added to the oxygen-nitrogen mixture flowing at the outside of burner flame through an injection feeder, and the extinguishing limit concentration of the powder was measured by a light attenuation method under the change of experimental conditions such as mean particle size, mean specific surface area, ambient oxygen concentration and powder material. Dry powders used are three kinds of commercial grade sodium hydrogencarbonate, potassium hydrogencarbonate and ammonium dihydrogenphosphate.
The results obtained are summarized as follows:
(1) The extinguishing limit concentration of screened uniform powder lowers with the decrease of the oxygen concentration in ambient gas flow and the particle size.
(2) The extinguishing limit concentration is in a linear relation with the reciprocal of specific surface area of the powder, and the plotted line approximately passes the origin.
(3) The extinction effect for three kinds of dry powder used here is decreased in the order of KHCO₃ > NaHCO₃ > NH₄H₂PO₄. The cause that the NH₄H₂PO₄ powder for practical use is in appearance more effective than NaHCO₃ will be mainly originated in the small mean particle diameter.
(4) The flame extinction effect of two component mixture with NH₄H₂PO₄ decreases in comparison with the ones of individual powder and other combination without NH₄H₂PO₄.
The authors also suggest in this paper that the slope of the line mentioned in (2) may be used as an evaluation index of the fire extinction ability of dry powders.

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Polyvinyl chloride (PVC) resin is widely used as an insulation or a jacket for distribution cable (F-Cable). The F-Cable would sometimes be ignited by an arc which occurs between deposited carbon caused by a scintillation discharge and an electric wire under wet polluted conditions.
Recently, the importance of fire breaking out in electric appliances and devices has been established, and tracking and ignition of polymers as an origin of fire has been scrutinized. Electric fire phenomena and these processes caused by tracking failure has been studied by many investigators, but no satisfactory solutions seem available as yet.
In this paper, first of all, in order to investigate the electric causes and processes of tracking failure and ignition, tracking tests were carried out by a test method which complied with the IEC (International Electrotechnical Commission) tracking test using the specimens with an artificial cutting groove of a commercial two-conductors F-Cable insulated by PVC resin. The electrolyte of 20 +3/-0 mm³ quantities is dropped in the center of cutting groove which has a width of 4 mm and a depth to conductor exposed. The electrolyte used is the same A-solution (0.1% NH₄Cl in distilled water) as the IEC test method provides. A constant voltage of 100 V (Effective value) was applied between one conductor and the other.
From these tracking test results of F-Cable, it is found that the free carbon is formed by the heat of scintillation, and that the waveform of current indicates the pulse shape. The pulse width of current measured with digital memory indicated from about 10 μs to 0.2 ms. After this stage, as the number of electrolyte drops increase, the arc occurs between the wet deposited carbon caused by a scintillation discharge and an conductor. The current waveform of the arc indicates half wave rectification. After this stage, the current waveform of the arc indicates distored alternating wave. The sheath or jacket is ignited by these arcs under test conditions in which the wet deteriorated parts are always in contact with the open air. These arcs will be the ignition source in this case.
Nextly, on the basis of the tracking model test results, the authors made a plan for electric fire protection equipment which responds to the various current signals in the tracking failure, and the electric fire protection equipment was manufactured for trial.
Thirdly, in order to reconfirm the response of present equipment against various current signals in the tracking failure under a load or no-load, the tracking model test was carried out. As the results obtained by the response reconfirmation test, the authors reconfirmed that this equipment had excellent frequency response, and responded to various current signals in the tracking failure under a load or no-load. On the other hand, it was clear that a fault current alarm of first class had no response to current signals in the tracking failure.
Finally, the trial manufacture equipment was proposed as the convenient method to protect the tracking failure and ignition of F-Cable for practical use.

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