Smoke ventilation in operational fire fighting: Part 2. Multi-storey buildings

The effect of Positive Pressure Ventilation (PPV) on compartment fires in a 1:4 scale four-storey building was investigated experimentally. The main goal in the experiments was to find out the optimum ventilation path and ventilation rate as a function of the elevation of the fire room. Also, the smoke movement in the staircase was studied to evaluate issues related to evacuation of the building. The main quantities measured were the total rate of heat release (RHR) and the vertical temperature distributions in the fire room and rooms connected to it, as well as in the staircase. When the PPV was arranged in accordance with the generally adopted practices in fire-fighting, the benefits of PPV could be well reproduced: the visibility along the path of the fire-fighter attack was improved, and the gas temperatures were lowered. However, the RHR of the compartment fire was increased by the application of PPV. An implication of this is that there exists an optimum PPV rate which sufficiently improves the operating conditions of the fire-fighters while keeping the thermal load on the structures in the fire room to a tolerable level.