Performance Criteria of Systems to Reduce Fire Damage by Prevention or Suppression

Performance requirements and approval criteria of fire extinguishing, suppressing and inerting systems are typically based on the benchmark merits of each system category at the time they were introduced, often many decades ago. This conventional way of rating systems has served well for use with prescriptive codes. Performance based code regimes however, require an alternative approach in order to allow optimisation of fire safety designs for actual structures or vital operations. At one end of the scale sprinkler systems are required to control or suppress fire so that it does not exceed the heat release rate at the time of system activation - which may be several megawatts of power or flame heights up to two thirds of the ceiling height. Some are rated as flashover prevention systems. Completely different is a requirement of clean agents to fully extinguish visible flames within a time frame and to prevent re-ignition. In between are systems that prevent rekindling and some that prevent spread by prewetting surroundings. Some new water based systems do not act on the fire itself but close in on it by creating a barrier of water mist around the protected object, while new fire prevention systems prevent or retard combustion. Smoke emissions by non-oxidizing smouldering, overheating or friction are stopped by mitigating actions triggered by early detection. Water mist systems are introduced as an alternative to traditional sprinkler and deluge systems. These systems use less water to obtain a protection, in most cases performing equivalent to or better than the systems they replace. Water mist systems are also used as a replacement of gas systems (Halon replacement). The water mist systems are to be tested in a test setup similar to its application, and some of the existing standards have quantitative measures of the performance of the system. Current performance ratings and code requirements are summarized and their applicability questioned from a fire safety engineering point of view. The possibility is addressed that listing agencies and testing laboratories may in the future, or even in the near term, provide diverse test results that can be applied in performance based fire safety design. The principle of application specific test protocols, as established for water based systems both in US and in Europe, is discussed as a model for gas extinguishing, inerting and fire prevention systems as well. The state of the art of modelling of various systems in order to simulate