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Assessment of risk of lowering of the cover of the compressed-air supported construction at the fire

Journal: Pozharovzryvobezopastnost/Fire and Explosion Safety (Vol.26, No. 4)

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Page : 50-57

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In article the risks of lowering of covers of compressed-air supported constructions (VOS) arising during the opening of all or a part of emergency exits from a construction are considered. Lowering of covers can lead to violation of functioning of doors. For prevention of lowering of VOS establish on the ways of evacuation of an arch of safety that it is integrated to additional costs and restrictions. For purity of assessment of the risk factor connected with lowering of a cover in article the fires leading to distribution of dangerous factors of the fire within VOS amount, but not to loss of an integrity of a cover are considered. The characteristic of fire risk of lowering of a cover is critical time of tkr of reduction of amount of a cover to some extreme value, for example, before reduction of amount of a cover twice of rather working hours. For receipt of engineering estimates it is offered to break process of lowering of a cover into two stages: the first stage - reduction of excessive pressure in a cover from working pressure up to the critical pressure during t 1 when preserving amount of a cover; the second stage - isobaric reduction of amount of a cover to limiting amount with a critical pressure during t 2. Critical time for VOS is equal to the amount of times of t 1 and t 2. Approximate analytical estimates of times of t 1 and t 2 depending on space-planning characteristics of VOS, number and the sizes of emergency exits from constructions, the mass of a cover, excessive working pressure in a cover are received. The example of calculations of t 1 and t 2 for the real compressed-air supported construction used for sporting events by amount about 27 thousand m3 is given. It is established that time of t 1 changes within seconds, and t 2 within 5-15 minutes. With settlement way existence of risk of lowering of a cover taking into account holding mass actions in VOS in case of which evacuation time from a cover changes within 4-10 minutes is confirmed. It is offered to use for increase in tkr technological system of a subtime of air in VOS which in case of the maximum feed rates of air can compensate substantially an air consumption through open doors. Formulas for assessment of times of t 1 and t 2 taking into account amounts of the given air in ventagregatama VOS are offered. Taking into account not fixed opening of doors in case of evacuation, very frequent device of opening of doors against the direction of evacuation, the assumption of a soft design of covers, the received time estimates of lowering of covers should be considered as the lower estimates of critical time. Further comparison of settlement critical times of lowering of covers with experimentally received values of times is necessary for the operated covers that will allow including, to specify effective consumption factor of m otv air through VOS doors.

Last modified: 2018-10-17 21:45:58