Bulletin of Japan Association for Fire Science and Engineering

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Foreign countries have long histories of building fires, and also recently in our country we have met very often serious disasters from year to year just as the case of Sennichi department store, and it is well known both at home and abroad that the extent of damage and the death rate per unit show higher tendency than the ones up to this time.
(1) Referring to some recent fires, protection equipments at the present states are divided into three main classes, as equipments for fire and smoke protection, fire escape and exhausting smoke, and then analyses are made. As the result of investigation them, it is known that escape trouble, death by falling to the ground and poisoning by smoke filling in highly closed interior zones in a building have been increasing remarkably.
Therefore, here the push-pull type air shutter is suggested so as to make prevention of accidents more effective.
(2) Discussing about the meaning and characterization of the air shutter, the comparison between a so called air curtain and the one is made, and its safety ratio and effect are reported in case of fitting out the shutter for the fire protection.
(3) The shutter for the fire protection can be designed by using following equations
Q₃+Q₁ = Q₁(2+K_D ) = Q₁(2+m · K_B )   ……………………………………… (1)
K_B = K_S · {5.8(υ₀/υ₁)^1.4· (H /E )^0.25+1} ……………………………………… (2)
K_S = (H /E )^1.1· {0.46(W /E )^-1.1+0.13} {0.04(V /E )^0.20+0.51} …………… (3)
where,     Q₁ : Push flow volume,            m³/min
Q₃ : Suction flow volume,         m³/min
Q₀ : Side flow volume,            m³/min
υ₁ : Push flow velocity,            m/s
υ₀ : Side flow velocity,            m/s
E : One side of push opening,            m
H : Axial distance between push opening and pull one,            m
V : Length of push flange,            m
W : Length of pull flange,            m
m : Safety factor of breaking
K_D : Design flow ratio
K_B : Breaking limit flow ratio
K_S : Shutting limit flow ratio

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There were carried out measurements of the burning rate of strips, rods and tubes of card board and incense stick, smouldering in downward propagation under natural convection. The effects of ambient temperature and specimen size on the burning rate were determined experimentally.

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The theoretical formula of the burning rate, derived from a simplified thermal model, is found to explain well the experimental results previously reported. Particularly in the case of tubes, the flow effect is emphasized rather than the radiation effect which is responsible for a few percent of increase in the burning rate. Qualitative interpretation of the stable shapes of burning surfaces in steady propagation is also suggested.

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