Air flow control equipment in chemical laboratory buildings

Apparatus for controlling the flow of exhaust of a fume hood having an exhaust passage and having a sash that is adjustable for providing a variable sash opening into the hood, said apparatus including

• sash position signal means for providing a sash position signal that is a progressively variable representation of the sash opening,
• exhaust means for discharging exhaust from the fume hood and thereby drawing air into the fume hood through said sash opening, and
• control means for said exhaust means including said sash position signal means and means responsive thereto, for causing the rate of exhaust flow to increase as the opening of the sash is increased through a first range up to roughly halfway open and to increase in a second range approaching full opening of the sash,
• said control means including regulating means for causing the increase of the exhaust flow rate versus increasing sash opening to be distinctively more rapid in said second range than in said first range of sash openings.

Apparatus for controlling the flow of air in a building module having predominantly special procedure rooms that are to be maintained different by a negative offset pressure from residual areas of the building module adjoining said rooms and for maintaining the residual areas at neutral pressurization relative to the building's exterior, said residual areas being connected by constricted passages to said special procedure rooms, said apparatus including

• an exhaust fan for discharging exhaust from the building module and an exhaust duct system extending from said exhaust fan to said special procedure rooms,
• a supply fan for drawing air into the building module and a supply duct system extending from said supply fan to said special procedure rooms, exhaust damper means for regulating exhaust flows drawn from the special procedure rooms into the exhaust duct system at controlled exhaust volumetric flow rates,
• supply damper means for regulating supply flows of air from said supply duct system to said special procedure rooms at volumetric flow rates lower than said controlled exhaust volumetric flow rates of said rooms, respectively, for maintaining the special procedure rooms at negative offset pressured relative to said residual areas,
• residual area damper means for regulating a flow of supply air from said supply duct system to said residual areas for making up the difference between the exhaust flows and the supply flows of said rooms, and
• means for maintaining the volumetric flow rates of the exhaust duct system and of the supply duct system in balance, said maintaining means including means for sensing and comparing the volumetric flow rates of the supply and exhaust duct systems and means responsive to said comparing means for regulating said residual area damper means for maintaining said balance.

Apparatus for controlling the flow of air in a laboratory building module which has multiple laboratory rooms from which exhaust is to be discharged, each laboratory room having at least one fume hood in which exhaust develops, said laboratory module additionally having residual areas adjoining said laboratory rooms and having restricted air passages between said residual areas and said laboratory rooms, said apparatus including

• an exhaust fan for discharging exhaust from the laboratory building module and an exhaust duct system extending from said laboratory rooms to said exhaust fan, said exhaust duct system including a fume hood exhaust duct for each fume hood,
• a supply fan for drawing air into the laboratory building module and a supply duct system extending from said supply fan to said laboratory rooms,
• one of said duct systems extending to said residual areas,
• exhaust damper means for regulating the volumetric exhaust flow rate of each of the fume hoods of each laboratory room into the exhaust duct system,
• supply damper means for regulating the supply of air to each laboratory room from the supply duct system at a supply flow rate that differs by an offset flow rate from the total flow rate of exhaust from such laboratory room, air at said offset flow rate passing between such laboratory room and said residual areas via said restricted passages, thereby causing the air pressure in the laboratory rooms to be offset from the air pressure in said residual areas,
• means for measuring the entire volumetric flow rate of the exhaust discharged from the exhaust duct system by said exhaust fan,
• means for measuring the entire volumetric flow rate of air provided to the air supply duct system by the supply fan, and
• residual area damper means for regulating the flow of air between said residual areas and said one of said duct systems at such a flow rate as to maintain essential equality between the entire volumetric flow rate of the supply duct system and the entire volumetric flow rate of the exhaust duct system.

Apparatus for controlling the flow of exhaust of a fume hood having an exhaust passage and having a sash that is adjustable for providing a variable sash opening into the hood, said apparatus including

• exhaust means for discharging exhaust from the fume hood and thereby drawing air into the fume hood through said sash opening, and
• control means for controlling the flow rate of the exhaust in said exhaust means, said control means including
• (a) face velocity sensing means for providing a face velocity signal, said face velocity sensing means having a first passage extending from outside a fume hood to a first opening inside the fume hood and having a first air velocity sensor in said passage, and
• (b) means responsive to said face velocity signal providing means for causing the rate of exhaust flow to increase as the opening of the sash is increased through a first range up to roughly halfway open and to increase in a second range approaching full opening of the sash, and
• (c) exhaust flow sensing means for providing an exhaust flow rate signal,
• said control means including regulating means responsive to said exhaust flow rate signal for causing the increase of the rate of exhaust flow versus increasing sash opening to be distinctively more rapid in said second range than in said first range of sash openings.