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In this series about rapid fire development (RFD), we have focused on the science behindflashover以及如何water is used to aggressively cool the gases and the environmentto reduce the heat-release rate and contain radiant heat. The third and final part of this series is a study of ventilation as a companion to using water for aggressive cooling.
Using science and data, the fire service has been re-examining the usefulness and the purpose of ventilation. This re-examination has led some fire departments to shy away from ventilation; some have instituted a no-roof-ventilation practice and rely instead on horizontal, mechanical, and hydraulic ventilation. Although these three types of ventilation work well and have their place in firefighting, vertical ventilation cannot be removed from the arsenal.
Vertical ventilation, used along with water, aggressively cools the fire and the environment by creating a natural travel path for hot gases, unburned particles of combustion, and steam to escape quickly and easily. These gases are lighter than cold air and naturally want to travel up.
相关的消防员培训
Vertical Ventilation: Should it Still be a Primary Tactical Assignment?
烟总是进入较低的大气压区域或区域。住宅房屋中的结构火有两个不同的大气压力区域：高区域和低区域。高压区位于结构内部，从火力产生的热量迫使空气膨胀和填充建筑物。膨胀的空气与高密度烟雾相结合，增加了房间的大气压力。因此，烟雾会将自己推向低压区，该区域不在结构之外。
大气压力是为什么消防员看到烟雾从任何结构发生的火灾中退出的原因 - 它遵循其自然路径，而自然路径已上下。一旦将水施加到火灾和环境中，烟雾将扩大，冷却并需要逃生路线。垂直通风为加热的空气提供了退出结构的自然途径。
There are two distinct flow paths that can either aid or hinder firefighters: the unidirectional and bidirectional flow paths. A unidirectional flow path (see photo 1) has only one travel direction, either going in or going out. Either hot gases, unburned products of combustion, and smoke will go out from the structure, or there will be a fresh supply of air coming into the structure. Notice in photo 1 how there is nothing but smoke exiting from the far-left window.
A bidirectional flow path (see photo 2) is two travel paths occurring at once: smoke is exiting in the top half of a structure while the bottom half has an incoming supply of air. The window in photo 2 has fire exiting from the top half while the bottom half is wide open for incoming air supply
Vertical ventilation, done correctly, creates a unidirectional flow path to allow smoke and unburned gases to exit a structure. A vent placed directly above the fire area forms a natural travel path for the gases and steam that is created once firefighters start to apply water on the fire and the surrounding environment.
那么，为什么消防服务不使用垂直通风呢？原因有所不同，但是一个共同的分母是轻巧的结构和失败时间。消防服务的发生速度更快，随着屋顶桁架的轻量级结构的增加，这意味着屋顶被火灾迅速妥协，对消防员来说太危险了。需要进行勤奋，以确保机组人员仍然可以进入屋顶；这涉及使用尺码来确定对消防员是否安全。
One tactic to help overcome lightweight roof trusses is to use two roof ladders. Typically, firefighters bring one roof ladder to vent the roof, but in the case of lightweight roof construction, two are more effective.
正如您在照片3中看到的那样，两个屋顶梯子彼此靠近，使两名消防员可以轻松地一起工作以进行垂直开口。每个消防员都有一个可以在该平台上工作的平台，而无需踏上屋顶本身。屋顶梯子在屋顶的顶部和底部受到支撑，从而取代了消防员的重量。消防员应该在屋顶上花费有限的时间 - 他们只能进行切割然后下车。
消防员需要在快速开发中取得巨大的方式进行积极进取的态度。一种方法是积极地冷却火，同时为结构通风。通风和激进的冷却并排携手减少闪存的实例并确保消防员安全。
Mark van der Feyst自1999年以来一直在消防部门，是格拉特福特堡（MI）消防局的消防员。他是加拿大，美国和印度以及FDIC的国际教练。他还是Residential Fire Rescue（188金宝搏是正规吗消防工程书籍和视频）。可以在mark@firestartraining.com.
MORE MARK VAN DER FEYST
Go High: Rungs Above the Roofline
Firefighting Basics: Aggressive Cooling and Preflashover Conditions
消防员训练Drill: Reverse Hold of Pike Pole or Roof Hook
Firefighting Basics: Rapid Fire Development and Aggressive Cooling
