Smoke control and ventilation

Ventilation is of vital importance in removing smoke, gases, and heat. Appropriate sky-hghts, roof hatches, emergency escape exits, and similar devices should be provided when the building is constructed. NFPA has several design documents that address smoke control and ventilation. 

In the case of large buildings with many occupants, e.g. shopping malls, smoke control and ventilation play a... 

Powered ventilation systems in chemical warehouses are typically used for some flammable gas and liquid storage areas (see Gas and Vapor Control, Section 6.6). Heating and ventilation systems and powered roof exhaust systems can be arranged to shut down automatically upon receipt of a fire alarm signal so as not to interfere with sprinkler system operations due to airflow. Furthermore, these systems can also be arranged for manual starting and full exhaust by the fire department for smoke removal during search and rescue operations. 

The System 80+ Standard Design Control Room Ventilation System provides continuous pressurization of the room to prevent entry of dust, dirt, smoke, and radioactivity originating from outside the room. Filtered outdoor air for pressurization is taken from either of two locations such that a source of uncontaminated air is available. Each intake location is monitored for radioactivity, toxic gases and products of combustion (see CESSAR-DC,... 

The heating, ventilation and air conditioning plans (HVAC-plans) contain data regarding radiators, waU-mounted fans, smoke extraction valves, ventilation hnks, blowers etc. Here again, process engineering has to see to possible coUisions with other plant components. This includes the small heating pipes as well as the control lines for smoke extraction valves. 

Special fire hazards - in the case of a building containing a special fire hazard, a protected lobby of not less than 0.4 m should be provided between the hazard area and the escape stairway. In addition the lobby should have permanent ventilation, or a mechanical smoke control system to protect the area from the ingress of smoke. 

Any processes or activities on the plant site that if incorrectly carried out might influence the safe operation of the plant should be presented and described examples of such processes or activities are vehicular traffic in the plant area, the storage and potential spillage of fuels, gases and other chemicals, intakes (e.g. of air for control room ventilation) or contamination by harmful particles, smoke or gases. 

Demand-controlled ventilation (DCV) is one approach to reduce energy consumption due to ventilation, that is gaining popularity in both industrial and nonindustrial applications. It is used in cases where ventilation requirements vary with time, regularly or irregularly. The control is based on a specified level of indoor air quality by means of continuous measurement of the parameters, that are expected to primarily determine the lAQ, such as the concentration of the main contaminant liberated from the production process. The principle is thus similar to the one in some better-known nonindustrial applications, e.g., CO2 levels in rooms with dense human occupancy (theaters, classrooms, etc.) or nicotine concentration in smoking rooms. See also Section 9.6. 

Most ventilators are powered in one direction with spring return. Thus, a pneumatic ventilator might be described as pressure to open or pressure to close. With the pressure to open type the ventilator will fail to the closed position under the influence of the return spring, ensuring the building remains weatherproof. Where ventilators are installed mainly as smoke ventilators it is important that they fail to the open position, so pressure to close ventilators should be used. A fusible link is normally fitted into the controls so that in the event of fire, affected ventilators will open automatically to release smoke and heat. 

Smoke ventilation is not intended to replace other forms of fire prevention and control but to work as an important component in an overall scheme. 

BS 7346, Components for smoke and heat control systems. Part 1 Specification for natural smoke and heat exhaust ventilators. 

Kaiserman MJ, Rickeryt WS (1992) Carcinogens in tobacco smoke benzo[a]pyrene from Canadian cigarettes and cigarette tobacco. Am L Pub Health 82 1023-1026 Kozlowski LT, Mehta NY, Sweeney CT, Schwartz SS, Vogler GP, Jarvis MJ, West RJ (1998) Filter ventilation and nicotine content of tobacco of cigarettes from Canada, the United Kingdom, and the United States. Tob Control 7 369-375... 

Other physical characteristics such as length, circumference, porosity, ventilation, and tobacco weight and density combine to determine the basic machine-smoked yields of tar , nicotine, and other substances. The complex interaction between these different design features has been extensively studied within the tobacco industry in order to carefully control the resulting product delivery (Browne 1990). 

The space where the sensory panel is trained has to fulfil certain criteria. A space which is temperature-controlled, has 100% outdoor ventilation, a filtration unit (e.g. active carbon), a Teflon layer on the walls, the floor and the ceiling, and displacement ventilation (from floor to ceiling) or a local exhaust is preferable. A space which is an empty room (no smoking), has walls, a floor and a ceiling that could be covered with a Teflon layer or cleaned with a nonsmelling agent, has a mechanical air supply with filtered air and has mixing ventilation with a certain minimum ventilation rate is acceptable. 

DISPOSAL AND STORAGE METHODS contaminated mineral oil can be disposed of by controlled ineineration alternatively, absorb in sand or other inert materials, and use for landfill at sites carefully chosen to avoid any risk of the oil causing contamination of water supplies store in a cool, dry location maintain adequate ventilation sources of ignition such as smoking and open flames are prohibited where Mineral Oil Mists are used, handled, or stored. 

Recently, a matched case-control study in a cohort of 3754 newborns in Oslo, Norway, showed an increased risk for bronchial obstraction in children living in apartments with high occurrence of plasticized polyvinylchloride, PVC, floorings. Many other factors such as ventilation, tobacco smoking and crowdedness (square meters per occupant) were included in the study. As the study showed a correlation between the risk of developing asthma and exposure to PVC floors, the authors suggested that the plasticizers, which mairdy consisted of di-(2-ethylhexyl) phthalate, DEHP, had adjuvant effect. ... 

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