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Title: Means for retarding the spread of fire from a building space
Claims: I claim: 1. Means for retarding the spread of fire from a building space, having air intake thereto, comprising: a. upwardly extending duct means having poor heat transmitting walls, for connecting the building space to the outside atmosphere, b. closure means, tightly closing and thermally insulating the building space from the duct means, c. means urging the closure means to open and thereby establish connection between the building space and the duct means, d. securing means, releasably securing the closure means in the closed position, and wherein e. for most effective operation, the following two conditions are satisfied, relying on the state of the art: ##EQU4## where A.sub.C (m.sup.2) is the cross-sectional area for the air intake to the building space, A.sub.d (m.sup.2) is the cross-sectional area of the duct means, .psi. (dimensionless) is a factor characteristic of the airtightness of the duct means, .delta. (dimensionless) is an orifice factor characteristic of the sizes of the area for air intake, .alpha. (dimensionless) is a factor describing, in terms of velocity head, the pressure losses at the entry and exit of fire gases to and from the duct means, and the frictional losses within the duct means when in operation, g (m/s.sup.2) is the acceleration due to gravity, .rho..sub.d (kg/m.sup.3) is the average density of the fire gases in the duct means when in operation, .rho..sub.e (kg/m.sup.3) is the density of air in the space from which it enters the building space when on fire, .rho..sub.a (kg/m.sup.3) is the density of the outside atmosphere, H.sub.1 (m) is the height of the duct means, z (m) is the elevation of the building space, p.sub.e (kg/m s.sup.2) is the pressure of the space from which the bulk of air enters the building space, p.sub.a (kg/m s.sup.2) is the pressure of the outside atmosphere, p (kg/m s.sup.2) is the desired pressure in the building space which, for correct operation in fire, is equal to or lower than the pressure in any adjoining space to be protected from the penetration of flames and fire gases, C (kg/m.sup.2 s) is a constant characteristic of the combustible materials in the building space, .phi. (m.sup.2 /kg) is the specific surface of the combustible materials, and G (kg) is the total mass of the combustible materials in the building space, whereby f. in the event of fire in the building space the securing means are actuated to release the closure means, so that the means urging the closure means moves the closure means to connect the building space with the duct means acting in conjunction with the air intake to i) drain away flames and smoke from the fire, ii) produce a depression in the building space thereby retarding the spread of fire, and iii) draw sufficient air to the building space to ensure relatively low fire temperature and a relatively short fire duration. 2. Means according to claim 1, wherein the building space is one of a plurality of buildings spaces, one above another at different floor levels, the closure means is one of a plurality of closure means for each building space, and each closure means has a means urging the closure means to open and a securing means. 3. Means according to claim 1, which includes, at least one release gate closing the upper end of the duct means from the outside atmosphere, and release gate opening means for opening the release gate. 4. Means according to claim 1, wherein the securing means is of a heat destructible material to be destroyed by a fire in the building space thereby allowing the closure means to open. 5. Means according to claim 3, wherein the release gate opening means includes a heat destructible member holding the release gate closed and capable of being destroyed by fire in the duct means to allow the release gate to open. 6. Means according to claim 2, which includes at least one release gate closing the upper end of each duct means from the outside atmosphere, and a heat destructible line holding the release gate in the closed position and extending along the interior of the duct means past each closure means, whereby flames entering the duct means from any of the building spaces will destroy the heat destructible line and open the release gate. 7. Means according to claim 1, which includes drop curtains for isolating the building space, except for air access thereto, from adjacent building space in the event of fire in the building space. Other info: Inventors: Harmathy, Tibor Z. (Ottawa, CA, US) Application Number: 583519 Filing Date: 1975-06-04 Publication_date: 1976-05-11 Assignee: Canadian Patents and Development Limited (Ottawa, CA) Primary Class(es): 52/1 49/1, 454/357, 454/369 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Murtagh, John E. Assistant Examiner: Attorney: Lemon; Francis W. |
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