There are five methods for smoke control system to manage smoke. These methods are used methods individually or in combination. The specific methods used determine the standards of design analysis, performance criteria, acceptance tests, and routine tests. The methods of smoke control consist of: compartmentation, dilution, pressurization, air flow, and buoyancy.
The compartmentation method provides passive smoke protection to spaces remote from a fire. The method employs walls, partitions, floors, doors, smoke barriers, smoke dampers, and other fixed and mechanical barriers. Smoke control system designers often use the compartmentation method in combination with the pressurization method.
The dilution method clears smoke from spaces remote from a fire. The method supplies outside air through the HVAC system to dilute smoke. Using this method helps to maintain acceptable gas and particulate concentrations in compartments subject to smoke infiltration from adjacent compartments. In addition, the fire service can employ the dilution method to remove smoke after extinguishing a fire. Smoke dilution is also called smoke purging, smoke removal, or smoke extraction.
Within a fire compartment, however, dilution may not result in any significant improvement in air quality. HVAC systems promote a considerable degree of air mixing within the spaces they serve and building fires can produce very large quantities of smoke. Also, dilution within a fire compartment supplies increased oxygen to a fire.
The pressurization method protects refuge spaces and exit routes. The method employs a pressure difference across a barrier to control smoke movement. The high-pressure side of the barrier is either the refuge area or an exit route. The low-pressure side is exposed to smoke. Airflow from the high-pressure side to the low-pressure side (through construction cracks and gaps around doors) prevents smoke infiltration. A path that channels smoke from the low-pressure side to the outside ensures that gas expansion pressures do not become a problem. A top-vented elevator shaft or a fan-powered exhaust can provide the path.