A time constant has been proposed to characterize the time it takes to fill an atrium space with smoke for design purposes. This was defined through the use of the empirical equation expressing the mass entrainment rate to the 312 power of the clear height. However, the equation holds only when the flame tip touches the smoke layer, and the flame temperature was taken to be 1100 K (827°C 1521°F).
In recent years, the atrium building has become commonplace. This paper explains the physical concepts of the steady fire, unsteady fire, zone fire model, and the fire plume that are the basis of atrium smoke management. The approach to smoke control design calculation in codes is based on the zone fire model concept. In the zone model, smoke forms an upward-flowing fire plume that reaches the ceiling and is considered to form a perfectly mixed layer under the ceiling of the room of fire origin.
In recent years, approaches to smoke management in atria have been introduced into many codes and engineering guides. This paper presents information that can be used for design analysis of atrium smoke management systems. Various approaches to manage smoke in atria are discussed Often a hot layer of air forms under the ceiling of an atrium, and this hot layer can prevent smoke from reaching the ceiling. A method is discussed for dealing with smoke detection when such a hot air layer prevents smoke from reaching the ceiling.
The use of the laboratory fume hood as the primary containment device in the laboratory has been a standard practice for almost half a century. Quantitative testing of the performance of these devices, however; is a more recent discipline. The use of the ANSI/ASHRAE 110-1995, Method of Testing Performance of Laboratory Fume Hoods (ASH RAE 1995) is becoming a standard specification in the purchase of new fume hoods, the commissioning of new laboratory facilities, and benchmarking fume hoods in existing facilities.
Dampness in residential buildings is detrimental to the health of the occupants and causes the growth of mold and decay in the fabric of the building materials. In Taiwan the average winter relative humidity is 80% and the average temperature is 15°C (59°F). It has been found that the average winter indoor moisture content in Taiwanese apartments can be higher than the outdoor content by as much as 15%. Although the main cause for the increased indoor humidity levels has not been identified, removing the moisture generated from shower baths can help reduce the humidity.
ANSI/ASHRAE 110-1995, Method of Testing Performance of Laboratory Fume Hoods (ASHRAE 1995) yields quantitative data about fume hood containment and can be used in a classical total quality management (TQM) approach to process improvement. This involves measuring process indicators, analyzing probable causes of poor performance, implementing changes to the process, and again measuring the indicators to determine the efficacy of the changes implemented.
Commercial cooking equipment exhaust systems have a significant impact on the total energy consumption of Foodservice facilities. It is estimated that commercial cooking exhaust ventilation capacity in food-service facilities across the United States totals 3 billion cfm (1 . 4 billion L/s) with an associated annual energy cost approaching $3 billion, based on an average of $1/cfm ($0.47 per L/s) per year. Significant energy and cost savings can be achieved by reducing ventilation rates.
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