Abstract: A multi-stack exhaust system and method including at least one fume hood, multiple exhaust stacks, each stack having a return duct with a return damper and a discharge duct with a discharge damper, a fan, a flow sensor, a first static pressure sensor for measuring the static pressure at the inlet duct, a second static pressure sensor for measuring the static pressure at the at least two exhaust stacks, and a controller.

Abstract: 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.

Abstract: An office air handling unit includes an intake, return and output system. The intake system transfers air from an external environment and through a preheating and cooling unit that regulates the temperature of the air entering the interior zone. The return system re-circulates air from the interior zone to the exterior zone through the use of a fan. The return system also regulates the temperature of the air entering the exterior zone by using a preheat unit and cooling unit. The output system allows for the transfer of air from the exterior zone to the external environment, re circulates the air back into the return system or re-circulates the air back into the intake system. The intake system allows for the transfer of air from the external environment to the return system to bypass the interior zone and provide fresh air to the exterior zone.

Abstract: A multi-stack exhaust system and method including at least one fume hood, multiple exhaust stacks, each stack having a return duct with a return damper and a discharge duct with a discharge damper, a fan, a flow sensor, a first static pressure sensor for measuring the static pressure at the inlet duct, a second static pressure sensor for measuring the static pressure at the at least two exhaust stacks, and a controller.