Design problems of the in-building fire pipeline based on low-flow fire hydrants of low and high pressure. Part 2. Criteria for use of low-flow fire hydrants
The application of new effective technologies for fire extinguishing with low-flow fire hydrants of low and high pressure with use of low-flow fire hydrants for in-building fire pipeline is substantiated. The main parameters of low-flow fire hydrants in accordance with the draft of the new version of SP 10 are considered. A formula for calculating the distance between fire-fighting cabinets is presented. In connection with the expanded range of fire hydrants, it is recommended to indicate the corresponding literary indices "PC s", "PC m", "PC-m-TRV" or "PC P " on the outside of The Doors of fire-fighting cabinets. It is proposed in the near future, similarly to traditional fire hydrants, to develop standards for technical requirements and test methods for equipment of low-flow fire hydrants with low, medium and high pressure: fire-fighting cabinets, fire valves, hand nozzles (or spray guns) of and technical means of connecting fire hoses with fire barrels (or spray guns). It is argued that one of the criteria for injuries excluding, i.e. the criterion for safe use of fire hydrants is not so much the limitation of pressure as the reduction in reactive force of the jet to safe value, value which for unprepared users of fire hydrants should not exceed 100 N. There is provided the design expression to determine the total reactive force of the jet stream in the hand nozzle of central and peripheral holes, axis of which is located under angle to the axis of the hand nozzle. A graph that establishes the relationship between pressure, equivalent area or equivalent diameter, reduced efficiency of the hand nozzles and reactive force of the jet stream is developed. It is proposed several options for application and design of the in-building fire pipeline depending on the specific purpose of the protected facility. Categories of persons (fighters of operational units of the fire department, members of the voluntary fire brigade, residents or personnel of the facility) who, depending on the specific purpose of the facility, can be involved in extinguishing fires with traditional and low-flow fire hydrants are regulated.