| 摘要 |
A fume hood exhaust stack system ( 10 ) and method utilize a variable speed fan ( 24 ) and an exhaust stack ( 28 ) having an adjustable cross-sectional area. Toxic exhaust from one or more fume hoods ( 12 ) is conveyed through a header ( 16 ) to the fan. The fan forces the exhaust through the exhaust stack, and the exhaust is then discharged into the atmosphere at a sufficient velocity and momentum to ensure that the exhaust reaches an environmentally sound altitude. A variable speed drive ( 36 ), programmable controller ( 34 ), flow signals ( 26 ), and static pressure and total pressure signals ( 20 ) are utilized to modulate the speed of the fan and the area of the exhaust stack to maintain the desired fan inlet pressure and exhaust velocity. |
