Abstract: A building system for a building including one or more storage devices storing instructions thereon that, when executed by one or more processors, cause the one or more processors to operate one or more pieces of building equipment associated with a building space based on a first operating mode. The instructions cause the one or more processors to receive an indication to update operation of the building space based on an emergency situation and responsive to receiving the indication to update operation of the building space based on the emergency situation, operate the one or more pieces of building equipment based on a second operating mode, wherein the second operating mode defines one or more second parameters for the one or more pieces of building equipment and is adapted to reconfigure the operation of the building space to address or mitigate the emergency situation.

Abstract: Methods and related systems for detecting inaccurate airflow delivery of an indoor unit of a climate control system are disclosed. In an embodiment, the method includes operating a fan of the climate control system by transmitting a requested airflow value from a controller of the climate control system to a controller of the fan. Additionally, the method includes collecting estimated airflow values of the indoor fan, and identifying a steady state condition of the climate control system. Further, the method includes determining airflow error values, and issuing at least one of a first alert to a user of the climate control system in response to at least one of the airflow error values being equal to or greater than an alert value, and a second alert to the user in response to each of the airflow error values being less than the alert value.

Abstract: The present disclosure describes a supply fan assembly including a controller, a memory operably coupled with the controller. The supply fan assembly further includes at least one environment sensor operably coupled with the controller and a fan supplying fresh air from an exterior environment into a structure according to instructions from the controller. Additionally, the operational data is generated by the at least one of the environment sensor and the controller, and the controller instructs the fan in response to the operational data generated during a pre-defined time period.

Abstract: A hatch device comprised by a main support body, a flow guide piece and an optional plug, which allows for minimum modifications in the service hatch cover's structure during installation.

Abstract: A system and method for providing a substantially constant volume exhaust or ventilation air terminal system is shown for controlling exhaust and/or return airflow rates in a system having a central fan or ventilator. The system and method permits zone-by-zone or area-by-area airflow regulation or control in non-demand areas in response to a demand or call for ventilation in demand areas. In one embodiment, the system employs at least one constant airflow controller or regulator situated in a damper. Another embodiment shows a combination of a first constant airflow controller or regulator situated or mounted on a damper with a second constant airflow controller or regulator situated in a duct associated with the damper. In still another embodiment, a constant airflow controller or regulator is provided in a duct, and used in combination with a solid damper.

Abstract: A method of self-balancing a plurality of mechanical components within a temperature control unit of an HVAC system. Each mechanical component is adjustable by the controller to vary airflow within the temperature control unit. For each mechanical components, a property is measured. An estimated condition of the mechanical component is calculated based on the measured property and known qualities of the temperature control unit. A desired condition for the mechanical component is determined based on a desired air condition within the HVAC system or building envelope. The estimated condition of the mechanical component is compared to the desired condition of the component. The condition of the mechanical component is changed using a controller to more closely align the estimated condition to the desired condition to achieve the desired indoor air condition. Steps are repeated until the difference between the estimated condition and desired condition is within a threshold value.

Abstract: The present disclosure provides a method and a device for adaptively regulating a static pressure of a ducted air conditioner, and a ducted air conditioner. The method includes: dividing the static pressure in an air duct into a preset number of sections; selecting the sections i and i+1, and detecting respectively the gears corresponding to the sections i and i+1, the rotating speeds Ri and Ri+1, and an actual working currents Ii and Ii+1; and judging whether Ii and Ii+1 are within the normal current ranges respectively; and selecting the final section according to the judging result. With the method, the air duct conditioner may automatically select and determine a section according to actual installation environments, and may automatically determine an optimum section in which the ducted air conditioner works.

Abstract: The present invention comprises an air flap arrangement (10) for a motor vehicle, comprising at least one air flap (16), an air flap carrier (12), on which the at least one air flap (16) is mounted rotatably about an air flap rotational axis (L), and a rotary drive (14), of which the torque-delivering drive shaft (32) is coupled to the at least one air flap (16) in a torque-transmitting manner, wherein a rotation angle limiting device is provided, which has a stop (38) secured to the air flap carrier and which has a counter-stop (28) that can be rotated with the at least one air flap (16), wherein the stop (38) and counter-stop (28), in a relative end position of the at least one air flap (16), are configured for contact engagement with one another, wherein the counter-stop (28) is configured on a counter-stop component (26) and an air flap face formation (20) is configured on an air flap component (18) configured separately from the counter-stop component (26), the counter-stop component (26) being formed of

Abstract: A control system for an HVAC system serving at least two zones, each zone receiving conditioned air by way of a zone duct, each zone duct including a zone damper having a first portion responsive to the static pressure in a HVAC system to open and bleed an amount of conditioned air past the damper when the static pressure of the system increases above a selected level, a second portion controlled by a actuator to move between an open and a closed position in response to a zone thermostat, and a coupling mechanism coupling the first and second portions to limit the relative movements of the two portions with respect to each other, and a biasing mechanism exerting a torque against the system static pressure differential. The first portion can be a single one-piece undivided blade pivotally mounted with a shell surrounding the zone damper.

Abstract: A set of methods and apparatus for efficiently pressurizing and ventilating an air-supported greenhouse or other structure requiring pressurization and ventilation. A method for efficiently pressurizing and ventilating an air-supported structure comprises directing any external wind flow and external wind pressure into mechanical flow means, such as a fan, or fans in parallel, operating in the intake direction, and into the internal space of the air-supported structure and out of the internal space of the air-supported structure through internal pressure regulating exhaust means, whereby the internal space of the structure will be ventilated and pressurized with the assistance of any external wind and the reliability of mechanical flow means (fans).

Abstract: The invention provides a positively pressurized housing ventilated by establishing and/or maintaining a pressure differential between at least two chambers in the housing. The invention also provides a method for ventilating a substantially closed housing that involves establishing and/or maintaining a pressure differential between at least two chambers in the housing.

Abstract: A zone damper having a first portion responsive to the static pressure in a HVAC system to open and bleed an amount of conditioned air past the damper when the static pressure of the system increases above a selected level, a second portion controlled by a actuator to move between an open and a closed position in response to a zone thermostat, and a coupling mechanism coupling the first and second portions to limit the relative movements of the two portions with respect to each other, and a biasing mechanism exerting a torque against the system static pressure differential. The first portion can be a single one-piece undivided blade pivotally mounted with a shell surrounding the zone damper.

Abstract: An air outlet valve for use in an aircraft is adapted during normal operation of the aircraft as a component of a cabin pressure control system for adjusting a desired pressure level in an aircraft cabin to remove air from an interior of the aircraft into the environment around the aircraft. The air outlet valve is further adapted during emergency ventilation operation of the aircraft as a component of a system for emergency ventilation of the aircraft cabin to introduce air from the environment around the aircraft into the interior of the aircraft. The air outlet valve comprises a nose-side valve flap, which is pivotable about an axis and is adapted to open or close a nose-side portion of an air outlet valve aperture, and a tail-side valve flap, which is pivotable about an axis and is adapted to open or close a tail-side portion of the air outlet valve aperture.

Abstract: The present application discloses a method of converting a single zone HVAC system to a multi-zoned HVAC system. More specifically, the present application discloses coupling at least one interface module to at least one controller of a heating unit, cooling unit, and blower assembly. Further, at least one thermostat may be positioned within each desired zone of a multi-zoned structure. The user may then position at least one register on at least one terminus of a duct within each zone. Thereafter, each thermostat within each zone is associated or linked via a communication channel or network with at least one register within the same zone, thereby forming at least one thermostat/register regime within each zone of a structure. The interface module may then be associated with the various thermostat/register regimes.

Abstract: A livestock production building includes an automatically controllable ventilation system which provides ventilation to livestock containment rooms. Incoming air may be heated, cooled and/or filtered, and is mixed and tempered before being delivered to livestock rooms. Substantially all exhaust air is filtered to mitigate environmental impact.

Abstract: An air-pressure-control system, the system comprising a system inlet, a system outlet, and a variable-speed fan configured to operate at a speed. A motor controller in communication with the fan is configured to control the speed of the fan. A differential-pressure transducer configured to monitor an air pressure at the system inlet and an air pressure at the system outlet. A closed-loop pressure controller in communication with the motor controller and differential-pressure transducer, wherein the pressure controller is configured to vary the speed of the fan based on the pressure differential between the inlet and outlet of the system, thereby controlling a pressure within a space. An ultraviolet kill chamber may be disposed between the inlet and outlet to expose airborne particulate to UV radiation. The system may also have a filter located within an air-flow path between the system inlet and system outlet.

Abstract: An aircraft having a user region therein within which pressurized air at selected pressures can be maintained using an environmental control system provided in the aircraft, and a utility region outside a utility boundary wall of the user region within which selected equipment for the aircraft is located. An internal combustion engine, provided as an intermittent combustion engine, is provided in the utility region having an air intake coupled to combustion chambers therein and a rotatable output shaft also coupled to those combustion chambers for generating force with an air transfer duct extends between the user region and the air intake so as to be capable of conveying pressurized air to that air intake.

Abstract: A zone damper having a first portion responsive to the static pressure in a HVAC system to open and bleed an amount of conditioned air past the damper when the static pressure of the system increases above a selected level, a second portion controlled by a actuator to move between an open and a closed position in response to a zone thermostat, and a coupling mechanism coupling the first and second portions to limit the relative movements of the two portions with respect to each other, and a biasing mechanism exerting a torque against the system static pressure differential. The first portion can be a single one-piece undivided blade pivotally mounted with a shell surrounding the zone damper.

Abstract: A nuclear chemistry laboratory adopts In-site Cutting Technique to remove the large-scale glove box contaminated by transuranium compounds. During removal operation, to prevent further spreading of contamination, it is necessary to build an alpha airtight quarantine tent around the glove box that is ready to be cut. Each section of the quarantine tent maintains a stable airflow and sufficient air exchange to meet negative pressure requirements and effectively prevent leak of ? contamination. It is necessary to install a negative pressure ventilation system to assure the operation of the quarantine tent that has a pressure gradient and allows airflow from low contamination area to high contamination area to effectively prevent spreading of ? contamination and also increase the safety for the transuranium contaminated glove box that is not in service.

Abstract: A room pressure controlling system having a supply air valve, a common exhaust air valve, controllers, and a differential pressure sensor. The controller gradually changes a supply and an exhaust airflow rates when there is an airflow rate change controlling operation, and calculates, based on a setting value and a pressure difference that is measured by the differential pressure sensor, a correction control output value for the valve being operated as the room pressure controlling valve, and if the sum value of the control output value and the correction control output value is a value that causes operation of the room pressure controlling valve in the direction opposite of the desired direction, suspends the output of the sum value, but if the value causes the room pressure controlling valve to operate in the desired direction, outputs the sum value to the room pressure controlling valve.

Abstract: A vent device comprising at least one control member pivotably supported in an opening in a frame, for movement, in response to differential gas pressure between opposite sides of the opening, between a closed position in which the control member(s) substantially blocks the opening and an open position in which the control member(s) leaves the opening substantially unobstructed for flow of gas therethrough, wherein the or at least one of the control members has associated therewith a restraining mechanism, operable to apply a force to the control member to influence movement thereof between its open and closed positions.

Abstract: A multi-tier approach for use in a detecting harmful agents conveyed by the air. In a first tier procedure, the air (in a structure or a predefined area) is continuously automatically screened at a plurality of different predefined locations by air sensors distributed in the area to be monitored. Each air sensor is configured to detect a potentially harmful substance that is carried by the air proximate the predefined location, to determine if a potentially harmful substance might be present, but need not identify a specific harmful substance. When a potentially harmful agent is identified by an air sensor in the first tier screening, a sample of the potential threat is collected, and a second tier procedure is initiated. The second tier procedure uses a manual test, such as a nucleic acid amplification and detection assay to detect any of a plurality of different specific threats in the sample.

Abstract: Example air duct systems for supplying conditioned air to comfort zones include various example inflatable tubes with various example dampers. The dampers move noticeably slowly and/or its opening is delayed to reduce the rate at which the tube is inflated by a supply air blower. Depending on the particular example, the damper can be either at the inlet end of the tube or at the tube's opposite end. In some examples, the damper is controlled by an actuator that is powered by air or driven by an electric motor.

Abstract: An air-pressure-control system, the system comprising a system inlet, a system outlet, and a variable-speed fan configured to operate at a speed. A motor controller in communication with the fan is configured to control the speed of the fan. A differential-pressure transducer configured to monitor an air pressure at the system inlet and an air pressure at the system outlet. A closed-loop pressure controller in communication with the motor controller and differential-pressure transducer, wherein the pressure controller is configured to vary the speed of the fan based on the pressure differential between the inlet and outlet of the system, thereby controlling a pressure within a space. An ultraviolet kill chamber may be disposed between the inlet and outlet to expose airborne particulate to UV radiation. The system may also have a filter located within an air-flow path between the system inlet and system outlet.

Abstract: An arrangement for measuring air flow includes a source of measurement values and a processing unit. The source of measurement values is operable to generate measurement values representative of a difference in pressure from air obtained on a first side of an obstruction and air obtained on a second side of the obstruction. The processing unit is configured to, in one case, convert any negative measurement values of the measurement values to a less negative value. The processing unit is further configured to perform low pass filtering on the measurement values and convert the filtered measurement values to a flow value.

Abstract: An air blower validator, a heating, ventilating and air conditioning (HVAC) system and a method of manufacturing thereof are disclosed. In one embodiment, the air blower validator includes: (1) a air pressure detector including a first pressure port configured to receive air from inside an air blower housing of an HVAC system and (2) an air collector configured to deliver the air to the first pressure port, the air collector including a pressure tap configured to couple to an opening in the air blower housing.

Abstract: Provided are animal containment systems and components, including single-use animal containment cages and modular rack units. Also provided are methods for assembling and using components of the animal containment systems.

Abstract: An air outlet valve for use in an aircraft is adapted during normal operation of the aircraft as a component of a cabin pressure control system for adjusting a desired pressure level in an aircraft cabin to remove air from an interior of the aircraft into the environment around the aircraft. The air outlet valve is further adapted during emergency ventilation operation of the aircraft as a component of a system for emergency ventilation of the aircraft cabin to introduce air from the environment around the aircraft into the interior of the aircraft. The air outlet valve comprises a nose-side valve flap, which is pivotable about an axis and is adapted to open or close a nose-side portion of an air outlet valve aperture, and a tail-side valve flap, which is pivotable about an axis and is adapted to open or close a tail-side portion of the air outlet valve aperture.

Abstract: An elevator system includes a mode switch configured to select one of a plurality of operation modes based on a state of the elevator cage, and a blower controller configured to control a blower to adjust pressure inside an elevator cage according to the selected operation mode.

Abstract: An air-pressure-control system, the system comprising a system inlet, a system outlet, and a variable-speed fan configured to operate at a speed. A motor controller in communication with the fan is configured to control the speed of the fan. A differential-pressure transducer configured to monitor an air pressure at the system inlet and an air pressure at the system outlet. A closed-loop pressure controller in communication with the motor controller and differential-pressure transducer, wherein the pressure controller is configured to vary the speed of the fan based on the pressure differential between the inlet and outlet of the system, thereby controlling a pressure within a space. An ultraviolet kill chamber may be disposed between the inlet and outlet to expose airborne particulate to UV radiation. The system may also have a filter located within an air-flow path between the system inlet and system outlet.

Abstract: An air-pressure-control system, the system comprising a system inlet, a system outlet, and a variable-speed fan configured to operate at a speed. A motor controller in communication with the fan is configured to control the speed of the fan. A differential-pressure transducer configured to monitor an air pressure at the system inlet and an air pressure at the system outlet. A closed-loop pressure controller in communication with the motor controller and differential-pressure transducer, wherein the pressure controller is configured to vary the speed of the fan based on the pressure differential between the inlet and outlet of the system, thereby controlling a pressure within a space. An ultraviolet kill chamber may be disposed between the inlet and outlet to expose airborne particulate to UV radiation. The system may also have a filter located within an air-flow path between the system inlet and system outlet.

Abstract: An air cleaner and method of controlling an operation of the same is disclosed. The air cleaner includes a cabinet having an inlet and an outlet; a filter assembly removing dust and smell particles from a room air; a fan; a sensor assembly sensing the composition of the room air; a supplier assembly providing at least one of insufficient components of the room air to a cleaned air; and a controller controlling the supplier assembly on the basis of data regarding the composition of the room air. In another aspect, the method of controlling the operation of the air cleaner includes steps of sensing a room air; measuring insufficient components of the room air and the amount thereof; and providing at least one of the insufficient components of the room air to a cleaned air.

Abstract: Systems and methods of determining static air pressure in an HVAC system are provided. Static air pressure is mathematically determined as a function of system parameters, such as blower speed, blower diameter, system volume airflow rate, and/or blower motor torque. The determined static pressure can be used during HVAC installation and during HVAC monitoring and maintenance.

Abstract: A device to prevent indoor release of carbon monoxide and smoke from indoor combustors (stoves, furnaces, fireplaces, etc.). The device is based on a discovery that safe operation of indoor burners requires the air pressure in the room housing the burner to be relatively high in order to prevent generation of reverse chimney flow and indoor release of exhaust gas (smoke and carbon monoxide), which are dangerous to building occupants. This device solves the problem by increasing the building internal pressure.

Abstract: A system for detection and treatment of chemical weapons and/or biological pathogens uses a detector system, an electrostatic precipitator or scrubber, a circulation system, and a control. The precipitator or scrubber is activated in response to a signal from the detector upon the detection of chemical weapons and/or biological pathogens.

Abstract: A method for controlling building interior air pressure that is different from external environment air pressure, wherein the internal and external air pressure difference can be significantly large. The internal and external air pressure difference is maintained through partitioning the internal airway using permeable porous walls. A method for building the permeable porous walls using unit permeable porous blocks including boxes of granular particulates is provided to ease not only the installation but also the repair and replacement of the permeable porous walls, and also to maximize the reusability of the materials used to build the walls.

Abstract: Cooling fluid pressure within a plenum of a cooling system is controlled by activating the cooling system, sensing pressure within the plenum in at least one zone of the data center, determining whether the pressure is within a predetermined pressure range, and modulating at least one of a plurality of automatically adjustable vents in response to the pressure being outside the predetermined pressure range.

Abstract: A method and device for preventing distribution of fire gases in a ventilating system that serves a number of fire compartments (15, 16), the ventilating air, during normal operating conditions, having a certain predetermined direction of flow at the inlet side and the outlet side of the fire compartments (15, 16). It is significant that when a predetermined lowest pressure drop is registered, for the ventilating air in the direction of flow, over a measuring spot at the inlet side or the outlet side, a blocking is effected of the flowing area of the ventilating air past the measuring spot.

Abstract: A differential pressure detecting system having a compliant first chamber, which is contained within a second environment, in combination with a sensor system for monitoring change in volume/shape of the compliant first chamber. In use the internal volume of the compliant first chamber is caused to access a first environment, so that pressure differences between the first and second environments can be detected via monitoring of change in volume/shape of the compliant first chamber. The compliant first chamber expands when the pressure therein is greater than that in the second environment, but does not expand, or decreases if already expanded, when the pressure in the second environment is equal to or greater than that inside the compliant first chamber. The detector system can be of any functional type that does not significantly affect the compliant first chamber volume/shape by its interrogation thereof in developing a signal.

Abstract: A building protection system and method is provided which is responsive to the release of hazardous agents both outside and inside of a protected building. For an outside release, an array of sensors surrounding the perimeter of the building is triggered to provide and indication that an external release has occurred. These external sensors operate in real time and are set at relatively high thresholds to prevent false positives. Upon initial detection of a release in a concentration above the threshold level of a perimeter sensor, a central processor connected to receive a release signal from the sensor will shut down all external air exchanges for the building and activate an over-pressure system for the building interior to insure that contaminated external air does not enter. Exterior sampling inlets are monitored to determine if high agent concentrations exist as a confirmation of the indication given by the perimeter sensors.

Abstract: A system for controlling make-up air apparatus for a controlled building space includes a first sensor for sensing the operation of a first appliance within a building space. The appliance causes the air to be exhausted from the controlled building space. There is a controller which receives a first signal from the appliance indicating that the appliance is activated. This signal is used to determine the air flow requirements between the controlled building space and an environment outside of the controlled building space such as to ensure a predetermined balance of the pressure of air within the controlled building space and the environment outside of the controlled building space. An air temperature sensor monitors the outside temperature. A back-flow damper and a preheater are also associated with the make-up air apparatus. A switch activates the preheater in the event that the temperature of outside air is below a predetermined level. The motor of a blower causes air to be drawn into the building space.

Abstract: The present invention provides a gas vent system for a vacuum chamber. The particle placed onto the wafer after loading out from a vacuum chamber can be greatly reduced by the system design. The gas vent system has a gas supply, an anti-vibrating tube, a gas regulator, a first line, a second line, a vent valve, and a filter. The anti-vibrating tube is connected after the gas supply for transferring gas without introducing vibration. The gas regulator is connected after the anti-vibrating tube for controlling a flow rate of the gas. The first line is connected after the gas regulator and has a first metering valve. The second line is connected after the gas regulator and is also connected in parallel with the first line. The second line has a second metering valve and an in-line valve in series. The vent valve is connected after the first line and the second line. The filter is connected between the vent valve and the vacuum chamber.

Abstract: An air handling system for heating, ventilating and air-conditioning systems to provide a variable air flow between an air treatment section and an air bypass section includes selectively sliding panels to vary the air flow between the air treatment section and the bypass section. Positioning of the panels can direct the flow of incoming air to be conditioned from all incoming air flowing through the air treatment section to all incoming air flowing through the bypass section and a mixture of incoming air flowing through the air treatment section and the bypass section.

Abstract: An air exchange and cleaning system for building enclosures, particularly indoor firing ranges, which removes particulate matter, such as lead and other heavy metals, and gun powder residues and gases from the enclosure atmosphere. An air handler unit includes a particulate matter separator and five stages of filtration which filter both powder and gases from the air. Ducts connect the air handler unit to the enclosed area of the building. The system includes a control system which starts the air handler unit, checks the status of the filters and other operating systems of the air handler unit and ensures that a required minimum negative pressure within the enclosure is achieved before signals are sent to permit operations within the enclosure. In the example of an indoor firing range, the air handler unit and duct system purges the range of possibly contaminated air, checks for satisfactory system operation and ensures a predetermined negative pressure is reached before turning on lighting to the range.

Abstract: A system controls the pressure at which conditioned is to be provided to one or more zones to be heated or cooled by the conditioned air. The system actively computes a setpoint for the pressure with a location in a duct system upstream of where any of the conditioned air is to be provided to the zones. The setpoint is computed as a function of the positional statuses of dampers within the duct system that regulate the flow of the conditioned air to the respective zones. The actively computed setpoint is compared with a sensed pressure in the duct system in order to determine whether the pressure in the duct system needs to be changed.

Abstract: A control strategy for rejecting supply air temperature disturbances in variable air volume air conditioning units using staged DX cooling. The strategy, and corresponding system, minimizes supply air temperature disturbances by controlling zone air dampers through a mapping of zone heat transfer requirements and damper positions. The mapping maintains a zone temperature setpoint, even with relatively large temperature swings caused by system-supplied conditioned air. The primary parameter that is controlled by the strategy of the present invention is a heat transfer rate associated with a temperature-controlled zone. The control strategy of the present invention estimates the zone heat transfer rate at a particular sampling instant and controls the damper position in response thereto.

Abstract: An apparatus and method for space pressure control in high containment laboratories. The system comprises a volumetric air flow controller and a differential pressure controller. The differential pressure controller couples to the volumetric air flow controller. To establish negative space pressurization in the laboratory, the differential pressure controller generates a variable offset signal for volumetric operation. In response to the offset signal, the volumetric air controller controls the ducted supply air to the laboratory at a set shortfall compared to the ducted exhaust air flow. The shortfall of ducted supply air creates a negative pressure which is also sensed by the differential pressure controller. The differential pressure controller reduces the variable offset signal to zero once the desired negative pressure level is attained. To maintain the negative pressure level, the supply and exhaust air flow rates must remain equal.

Abstract: A control device for operating drive motors of closure devices that is reponsive to air pressure differential inside and outside an enclosure and including a housing that will extend through a wall of the enclosure, vanes in the housing and adjustably weighted linkage interconnecting the vanes outside the housing and, depending upon the position of the linkage, operating sealed switches to actuate the drive motors.

Abstract: A barometric damper has a housing which is adapted to be coupled with a structure. The housing has an opening that allows spatial communication between the interior and the exterior of the structure. The damper also has a damper blade. The damper blade is movably coupled with the housing. The blade has an open position where the blade accommodates air passage through the opening and a closed position where the flow of air through the opening is substantially precluded. The damper also has a lever that is movably coupled with the housing. The lever has an attaching means that is used to attach the lever to the blade when desired. The lever is movable between a first position where the lever accommodates free movement of the blade in response to barometric pressure changes on opposite sides of the blade, and a second position where the lever maintains the attaching means against the blade, thus holding the blade in its closed position.

Abstract: A method for ventilating an animal enclosure using a plurality of closable ventilation openings. Sensors measure ambient outside temperature and ambient atmospheric pressure. A controller correlates said measurements for temperature, and pressure to determine a differential pressure between the interior of said enclosure and atmospheric pressure. Air is then transported by said fans to draw said air in a predetermined volume to achieve said determined differential pressure.