Abstract: The present disclosure relates to a method of operating an aircraft system, in particular for the purpose of fresh air supply, air-conditioning and pressurization of an aircraft cabin, having a first compressed air source formed by a first compressor charged with ambient air, ram air and/or precompressed air and driven by means of at least one motor and/or of at least one turbine and whose outlet is in direct or indirect communication with an aircraft cabin, said aircraft system having at least one second compressed air source whose outlet can be connected directly or indirectly to the aircraft cabin, wherein only the first compressed air source is in communication with the aircraft cabin in a first operating mode, wherein both the first and the second compressed air sources are in communication with the aircraft cabin in a second operating mode, and wherein the selection of the operating mode depends on the pressure of the ambient air such that the first operating mode is set at a high pressure of the ambien

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 “quick change” restrictor assembly that allows quick rebalancing of flow-pressures within a duct system. The invention comprises a removable restrictor plate, a branch circuit for receiving the plate, and a means for retaining the restrictor plate to the branch circuit. The circuit includes a feature that allows for removal and installation of the restrictor plate without removing the branch circuit, inlet or outlet ducting. The quick change restrictor will not require bonding and can be installed easily from outside the duct without any disassembly. The restrictor may also have various clips or tabs to reinforce the slot the restrictor plate is inserted into. The restrictor may also have a smart part number and color code that is visible from outside the duct allowing easy removal, identification and inspection.

Abstract: An arrangement for supplying humidified ambient air for an aircraft comprises a first line arrangement (22), which brings up supply air and from which the supply air is blown into the aircraft interior (10). This arrangement further comprises an evaporating device (32), which supplies a steam flow, the pressure of which corresponds at least approximately to a predetermined pressure value lying above a requisite interior pressure of the aircraft. A second line arrangement (36, 38, 40), which opens into the first line arrangement (22), carries the steam flow. Disposed in the second line arrangement (36, 38, 40) is an optionally adjustable aperture arrangement (52) for lowering the pressure of the steam flow.

Abstract: A vent baffle includes a vent panel having a vent panel opening; a blowout panel carried by the vent panel and covering the vent panel opening; a plurality of fastener openings provided in the blowout panel; a plurality of tear slits communicating with the plurality of fastener openings, respectively; and a plurality of panel fasteners extending through the plurality of fastener openings, respectively, and engaging the blowout panel. A vent baffle system for an aircraft and a method of venting an air flow path between a sidewall monument or structure and an aircraft sidewall in an aircraft fuselage of an aircraft are also disclosed.

Abstract: A cabin pressure control system (CPCS) software control logic modification may boost the voltage applied to a motor when conditions are sensed indicating a combination of larger than normal cabin pressure and cabin rate error conditions. The motor may be part of an open-loop system for operating a butterfly valve that may regulate outflow from the aircraft cabin. The larger than normal cabin pressure and cabin rate error conditions may be an indication that the outflow valve is not responding in a normal manner, potentially caused by excessive loading to the motor or motor degradation. By boosting the motor voltage during excessive load conditions or with a degraded motor, CPCS performance and robustness may be improved.

Abstract: The present invention relates to a compressor arrangement with at least two compressors, wherein the compressor arrangement includes an intake chamber directly provided upstream of the at least two compressors together on the suction side.

Abstract: An integrated environmental control system for a cargo stowage compartment in a mobile platform, for example in a commercial passenger jet aircraft. A fire detection/suppression subsystem is integrated together with an airflow management system. The airflow management system operates to circulate, and optionally to heat or cool, air withdrawn from a cargo stowage compartment of the aircraft before the air is released back into the cargo stowage compartment. A fire suppression substance, for example, Halon gas, can be discharged directly into a recirculation duct of the airflow management system, thus reducing the duct work required to achieve fire suppression and ventilation operations for the cargo stowage compartment. The integration of the fire detection/suppression and airflow management system operations reduces the overall amount, complexity and weight of the ducting employed in a cargo stowage compartment of a commercial jet aircraft.

Abstract: A valve is provided for controlling a flow of a fluid between a first environment and a second environment. The valve includes a frame adapted to fit within a perimeter of an aperture in a divider separating the first environment from the second environment. The valve additionally includes a first gate movable within the frame to control a flow of the fluid through the aperture between the first environment and the second environment. The first gate includes a substantially aerodynamically clean surface substantially free from protrusions disrupting the flow of the fluid over the first gate surface. Additionally, the first gate includes a trailing edge having a baffle adapted to cover an aft edge of the frame when the first gate is positioned to have a small opening angle. The baffle includes a plurality of 3-D notches in a front side of the baffle.

Abstract: An integrated power and cooling machine having an indirect regenerative air cooling feature may be useful for providing power and environmental control to both ground vehicles, such as tanks, and aircraft, such as helicopters and airplanes. The integrated power and cooling machine may prevent contamination of the conditioned supply air by isolating the conditioned supply air from the machine lubricating and heat transport fluid (e.g., operating fluid) that may leak into the conditioned supply air. Furthermore, the integrated power and cooling machine may utilize a lower energy source from the engine, thereby reducing energy consumption and improving system efficiency. In addition, a flow mixing device may enhance airflow to improve cooling performance.

Abstract: A multi-spectral shield and associated inlet structure is provided for reducing the signature of an air inlet port defined within an exterior wall of an aircraft, ship, or land-based vehicle across radar and infrared wavelengths. The multi-spectral inlet shield includes a plate disposed in front of the air inlet port. The plate is sized to visibly eclipse the air inlet port, when viewed from a direction perpendicular to the plate. The plate is supported in this position by a plate mount or splitter that extends from within the air inlet port and attaches to the plate. A support may optionally combine with the splitter to support the plate in this position. Air passes behind the plate and into the air inlet port via a channel defined around at least a portion of the plate.

Abstract: An air outlet device for a vehicle, especially for an aircraft, comprises a nozzle body with an air intake opening and an air outlet opening. The air outlet device further comprises a holding element formed with an accommodating opening having the nozzle body supported therein for rotation about a longitudinal axis extending through the air intake opening and the air outlet opening, and a valve body arranged coaxially within the nozzle body and guided by the holding element. Upon rotation of the nozzle body, the valve body can be displaced in the nozzle body between a closing position for blocking the air outlet opening and a maximum opening position for clearing the air outlet opening to the maximum extent. The valve body is of a hollow configuration.

Abstract: An air outlet device (1) for vehicles, in particular airplanes, comprises a panel (2) with at least one receiving opening, an air outlet (3) arranged in the receiving opening, and a sealing means (6) sealing the air outlet (3) and the panel (2) against each other. At the panel (2) and/or the air outlet (3), a securing means (8) is configured, it serves to mount the air outlet (3) to the panel (2). During the assembly of the air outlet device (1), the securing means (8) holds the air outlet (3) in a defined position in the panel (2) so that curing adhesives can be used as sealing means (6) without any problem.

Abstract: The present invention relates to A reduced bleed vapor compression cycle environmental control system for an aircraft. The environmental control system provides conditioned external ram air to compartments such as the cabin, the flight deck, avionics compartment, and other equipment compartments, where conditioned air is needed. The system includes a first compressor for compressing the external ram air to cabin pressure and an evaporator for cooling the external ram air to a desired temperature. The system further includes a low-pressure water separator for removing moisture from the ram air prior to the external ram air being delivered to the compartment(s). The ram air compressor as well as a compressor for a refrigerant loop are driven by a turbine that expands a minimal amount of bleed air from an engine.

Abstract: An air outlet device for a vehicle, especially for an aircraft, comprises a nozzle body with an air intake opening and an air outlet opening. The air outlet device further comprises a holding element formed with an accommodating opening having the nozzle body supported therein for rotation about a longitudinal axis extending through the air intake opening and the air outlet opening, and a valve body arranged coaxially within the nozzle body and guided by the holding element. Upon rotation of the nozzle body, the valve body can be displaced in the nozzle body between a closing position for blocking the air outlet opening and a maximum opening position for clearing the air outlet opening to the maximum extent. The valve body is of a hollow configuration.

Abstract: The present invention relates to an electrical power and cooling system for use in an aircraft having at least one engine. The electrical power and cooling system comprises a single shaft, a power turbine mounted on the shaft for receiving fresh pressurized air from the at least one engine, a cooling turbine mounted on the shaft and receiving the fresh pressurized air from the at least one engine, a generator mounted on the shaft, and a fan mounted on the shaft for creating a flow of cooling air. The system further has a condenser for removing moisture from the air exiting the cooling turbine and a mixing chamber for mixing the cooled dry air with recirculated cabin air. The electrical power and cooling system delivers conditioned air to a cabin and/or a flight deck onboard the aircraft and electrical power to the aircraft's electrical systems.

Abstract: An air outlet device (10) for a vehicle, especially for an aircraft, comprises a nozzle body (40) with an air intake opening (44) and an air outlet opening (46). The air outlet device (10) further comprises a holding element (14) formed with an accommodating opening (36) having the nozzle body (40) supported therein for rotation about a longitudinal axis (42) extending through the air intake opening (44) and the air outlet opening (46), and a valve body (68), arranged coaxially within the nozzle body (40) and guided by the holding element (14). Upon rotation of the nozzle body (40), the valve body (68) can be displaced in the nozzle body (40) between a closing position for blocking the air outlet opening (46) and a maximum opening position for clearing the air outlet opening (46) to the maximum extent. The valve body (68) is of a hollow configuration.

Abstract: A system and method for providing an air curtain for impeding the entry of dust, dirt, debris, smoke, insects and other airborne particulate matter into an interior area of an aircraft without the need for disposing heavy, bulky and high power consuming blower assemblies above the opening in the aircraft. The invention comprises a pair of air intake ducts each having a fan disposed therein. The fans draw an ambient airflow into the air intake ducts. Pressurized air from a power unit associated with the aircraft, such as an engine or auxiliary power unit, is injected into the air intake ducts. This has the effect of significantly accelerating the airflow in the air intake ducts to a velocity suitable for forming an air curtain. The air intake ducts are coupled to a manifold having a length sufficient to substantially span the opening of an aircraft at which the air curtain is formed.

Abstract: An air conditioning system and method are provided for use in an aircraft having a pressurized area and an unpressurized area. The air conditioning system includes an air conditioning pack located in the unpressurized area of the aircraft that conditions fresh air. The air conditioning system also includes a first air duct for directing a flow of recirculation air from the pressurized area, through a pressure bulkhead, and into the unpressurized area. A mixer is also provided and advantageously positioned in the unpressurized area for mixing the conditioned air from the air conditioning pack and the recirculation air from the pressurized area. Advantageously, the mixer obviates the need for a mix manifold and saves valuable space for passengers, cargo, and other aircraft equipment. The air conditioning system also includes a second air duct that directs the mixture of conditioned air and recirculation air from the mixer to the pressurized area of the aircraft.

Abstract: An air conditioning system and method are provided for use in an aircraft having a pressurized area and an unpressurized area. The air conditioning system includes an air conditioning pack located in the unpressurized area of the aircraft that conditions fresh air. The air conditioning system also includes a first air duct for directing a flow of recirculation air from the pressurized area, through a pressure bulkhead, and into the unpressurized area. A mixer is also provided and advantageously positioned in the unpressurized area for mixing the conditioned air from the air conditioning pack and the recirculation air from the pressurized area. Advantageously, the mixer obviates the need for a mix manifold and saves valuable space for passengers, cargo, and other aircraft equipment. The air conditioning system also includes a second air duct that directs the mixture of conditioned air and recirculation air from the mixer to the pressurized area of the aircraft.

Abstract: An integrated environmental control (IEC) system includes a decontamination Pressure Swing Adsorption (PSA) system in which a contaminated decontamination bed is purged through a purge exhaust duct and subsequently dumped overboard through a purge ejector. The energy from a high pressure drain duct serves as the primary motive force for the purge ejector to create a sub-atmospheric region therein and reduce back pressure upon the PSA filtration system. The reduced back pressure creates additional pressure drop across the PSA filtration system which improves performance. Risk of the purge exhaust duct and the purge ejector freezing in a low temperature environment is further minimized by mixing the purge exhaust with the relatively warmer high pressure drains.

Abstract: In an air conditioning system for an aircraft, two pre-mixing units respectively mix cold air from two air conditioning units with recirculated fuselage interior air from two recirculation units, to prepare two pre-mixed air flows that are both directed into and mixed together in a common air distribution mixing chamber, from which mixed air distribution lines branch off to respectively associated separate air conditioning zones within the fuselage. Post-mixing units are respectively interposed in the mixed air distribution lines and respectively mix additional quantities of recirculated fuselage interior air into the mixed air distribution lines. Thereby, the admixture of recirculated air is divided into at least two stages, the system provides redundant failure tolerant operation, and the danger of ice formation in the air lines is reliably prevented even while the air conditioning units provide cold air at a temperature below the water freezing point.

Abstract: In an aircraft, tap water is filtered, vaporized and injected into a trim line of an environmental control system. Filtering is performed by a reverse osmosis filter. Hot, humidified air leaving the trim line is supplied to a cabin of the aircraft.

Abstract: An aircraft air-conditioning system provides ventilation, air-conditioning and fire protection for a below-deck stairwell and cargo hold that may be equipped with passenger sleeping compartment containers. An air mixing unit mixes fresh air and recycled air to supply mixed air through a first supply air main line (31) and a supply air unit (21) into the freight hold (4), and through a second supply air main line (32) into the stairwell (5). A trimming air unit (7A) provides hot bleed air from the aircraft engines into the mixed air supplied through the first and second supply air main lines (31, 32). An exhaust air line (11) extracts exhaust air from the freight hold (4), while an exhaust air supplemental line (15) extracts exhaust air from the stairwell (5), both of which are connected to an exhaust air main line with an exhaust air ventilator (16) that blows the exhaust air overboard. A bypass line (8) provides bypass air if needed for the demands of the ventilator (16).

Abstract: The device involves the placement of an air pump turbine and the aircraft outflow valve in a duct through which all the air flows, with the turbine shaft attached to that of an electric generator, to a hydraulic pump, and to the N2 and accessory gearbox inside the engine, the air is also sent through a duct to strike inclined against the tips of the fan blades and against the tips of the first stage of the low speed compressor blades of the turbine engine.

Abstract: Increased efficiency of operation in pressurized aircraft may be obtained by employing pressurized air to be discharged from an aircraft cabin 10 as combustion air by applying it to the inlet 42 of a cycle compressor 40 whereat it is compressed before being fed to a combustor 52. Fuel from a source 64 is combusted within the combustor 52 and drives a high pressure turbine 48 as well as a low pressure turbine 30, either one of which may drive a load 56, 58 to provide electrical power for the aircraft. In addition, a load compressor 20 provides air to an environmental control system including an ECS turbo machine 88 and a bypass 110 for delivering conditioned air to the cabin 10.

Abstract: The present invention relates to a pressure regulation system for maintaining the air pressure within a defined space at a substantially constant level. The pressure regulation system comprises a housing and a flexible diaphragm within the housing which divides the housing into first and second chambers. The first chamber contains air at a desired or reference pressure. The second chamber communicates with the defined space and contains air at the same pressure as that in the defined space. The system further includes a laser system for detecting movement of the diaphragm due to pressure imbalance between the first and second chambers and a system for introducing air into or withdrawing air from the defined space when a pressure imbalance is detected. The pressure regulation system of the present invention has particular utility in aircraft systems for maintaining substantially constant pressure in the passenger cabin.

Abstract: A heat ejection device is disclosed for a heating system. The heat ejection device is adapted to mix ambient air from an interior with bleed air from a heat source. The heat ejection device includes a housing with an inner passage, an inlet and an outlet. The inlet is adapted to channel ambient air into the housing. The outlet is adapted to channel mixed heated and ambient air out of the housing. A dispenser is located in the housing between the housing inlet and outlet and includes an inner chamber which is adapted to receive heated air from a bleed line. The dispenser has a plurality of apertures formed in it which permit air to flow from the inner chamber into the inner passage for mixing with ambient air to form a flow of mixed air. An acoustically absorptive inlet liner is mounted on an inner surface of the housing at the housing inlet. The absorptive inlet liner is adapted to direct ambient air past the dispenser to minimize turbulence and absorb noise.

Abstract: The device involves the placement of an air pump turbine and the aircraft outflow valve in a duct through which all the air flows, with the turbine shaft attached to that of an electric generator, to a hydraulic pump, and to the N2 and accessory gearbox inside the engine, the air is also sent through a duct to strike inclined against the tips of the fan blades and against the tips of the first stage of the low speed compressor blades of the turbine engine.

Abstract: An outflow valve for a cabin pressure control system of an aircraft cabin includes an aft door that is modified to disrupt or increase speed of cabin air flowing past the aft door and out of the outflow valve. The aft door may be modified by notches formed in its leading edge. In the alternative, the aft door may be modified by through-holes formed behind the leading edge. The outflow valve also includes a forward door. Bolt heads or a baffle may protrude from an inner surface of the forward door to disrupt or slow down cabin air flowing over the inner surface of the forward door and out of the outflow valve.

Abstract: The present invention encompasses a system and method for insulating an aircraft passenger cabin from ambient temperatures without the need for insulation blankets. Hot bleed air flowing through a network of fluid passageways is directed into sealed bays formed between the outer skin of the fuselage and the wall panels of the passenger cabin. As the hot bleed air rises through the sealed bays, it insulates the interior of the passenger cabin from the outside ambient temperatures. The outer skin of the aircraft acts as a heat exchanger by removing heat from the bleed air before it is introduced into the cabin. The bleed air maintains the cabin at a comfortable temperature without the need for air conditioning when the aircraft operates at high altitude.

Abstract: The present invention provides a multi-mode secondary power unit comprising a first starter/generator unit operably coupled to a shaft. The first starter/generator motor is operable in a motor mode for causing rotational movement of the shaft and is operable in a generator mode for generating electric power from rotational movement of the shaft. A thermal engine is operably coupled to the shaft and is operable in a fuel burning mode for causing rotational movement of said shaft and is operable in a non fuel burning mode for receiving rotational movement from the shaft. A load compressor is operably coupled to the shaft for pressurizing air to a predetermined level.

Abstract: An air supply system for an aircraft cabin reduces the concentration of contaminations of the air in the cabin by a flexibly controllable valve system that comprises pairs of valves which on the one hand are ganged to respective air openings. One valve of a pair is connected to a fresh air or mixed air supply line. The other valve of a pair is connected to a suction or exhaust duct. Thus, depending on which valve in a pair is open and which is closed, the respective air opening can function as an air outlet for supply of mixed or fresh air into the cabin or as a suction port. Such a system permits a flexible volume control of the supply of fresh air into selectable cabin sections as well as a flexible volume control for the removal of used air from respective cabin sections. Additionally, it is now possible to increase the size of the non-smoking section at the expense of the smoking section or vice versa simply by a respective valve control.

Abstract: An aircraft subsystem provides the aircraft with all its electrical and conditioned air requirements without requiring the extraction of either shaft power and/or pressurized air from the aircraft's main engines. At the core of this subsystem are two rotating assemblies journaled on non-oil lubricated bearings to a housing. One assembly includes a cooling turbine, a starter/generator, a core compressor, and a high pressure stage of a two stage axial turbine, all mounted on a single shaft. A combustor is disposed between the core compressor and the turbine. The other assembly is comprised of the low pressure stage of the axial turbine coupled to a load compressor via a second shaft. The high pressure turbine stage and cooling turbine are sized to drive the core compressor and starter/generator which provides all the aircraft's electrical needs both on the ground and inflight.

Abstract: A cooling system is provided for compartments containing a heat generating apparatus, such as solid state variable speed constant frequency system, whose functionality is essential and whose cooling needs vary significantly during use. A main coolant channel is used to provide cooling to the heat generating apparatus under normal operating conditions. During an overtemperature condition; an auxiliary coolant channel provides additional coolant to the heat generating apparatus. Both of the channels are partially disposed within the heat generating apparatus, and they are both completely separate and free of fluid communication with each other. Each channel also contains a pump, such as a fan, for applying a motive force necessary to deliver the coolant to the heat generating apparatus.

Abstract: An environmental control system has an air cycle machine that includes a compressor, a cooling turbine, a motor/generator, and a power turbine all mounted on a single shaft. The power turbine receives bleed air from the aircraft's engine and has a variable geometry inlet nozzle that adjusts the air flow rate therethrough without significant throttling. Downstream of the nozzle the power turbine extracts the expansion energy from the bleed air while cooling it. This is used to drive the other components of the air cycle machine, and in particular the motor/generator which generates electricity.

Abstract: An apparatus and method of providing an Environmental Control System (ECS) for use in conjunction with a turbine engine power plant, to deliver a flow of purified, conditioned air to an enclosed space, such as an aircraft cabin. The ECS includes contaminate neutralization means to neutralize airborne chemical and biological agents.

Abstract: A compact, lightweight integrated environmental control (IEC) system for a helicopter incorporates in operative combination an environmental control system (ECS) and a nuclear/biological/chemical life support system (NBC LSS). The IEC system includes a refrigerant subsystem, a regenerative heat exchange apparatus, a decontamination subsystem, and an airflow distribution network, and is operative to provide super-cooled, super-dry, decontaminated airflow, in seriatim, directly to left and right mission equipment package bays and the cockpit for cooling of avionics/electronic modules and crew comfort. The IEC system is further operative to directly provide cooled, super-dry, decontaminated airflow for cooling of avionics/electronic modules of the mid mission equipment package bay and for over pressurizing the left and right mission equipment package bays to preclude contaminant infiltration thereof.

Abstract: An air cycle machine (10) has four wheels mounted on a common shaft (20) for rotation therewith about a longitudinal axis (12), including a second stage turbine rotor (30) mounted to a first end (20a) of the shaft, a fan rotor (40) mounted to a second end (20b) of the shaft, a first stage turbine rotor (50) mounted to a central portion (20c) of the shaft, a compressor rotor (60) mounted to the central portion of the shaft in back to back relation to the first stage turbine rotor, the first and second stage turbine rotors being operative to extract energy from a flow of compressed air for driving the shaft (20), and the fan rotor (40) and the compressor rotor (60), in rotation about the axis, and first and second hydrodynamic gas film foil bearings (70, 80) for supporting the shaft for rotation about the longitudinal axis (12).

Abstract: An aircraft gas turbine engine is provided with a starting air turbine that is directly connected through the starter gearbox to the high pressure (HP) shaft and is provided with an apparatus to extract excess energy from engine compressor bleed air, return it to the engine, and to start the engine with compressed air from starting air sources, and to cool and provide compressed air for powering the Environmental Control System (ECS) and using the bleed air for cabin refreshening. The air turbine may be connected to a nacelle boundary layer bleed compressor to bleed boundary layer air from a forward portion of the nacelle to reduce nacelle surface drag. The ECS may be provided with a wing boundary layer bleed means which uses a cooling air fan in the ECS to draw cooling air through the heat exchangers in the ECS pack from the boundary layer air from a forward portion of the aircraft's wing to reduce its surface drag.

Abstract: An aircraft gas turbine engine is provided with a starting air turbine that is directly connected through the starter gearbox to the high pressure (HP) shaft and is provided with an apparatus to extract excess energy from engine compressor bleed air, return it to the engine, and to start the engine with compressed air from starting air sources, and to cool and provide compressed air for powering the Environmental Control System (ECS) and using the bleed air for cabin refreshening. The air turbine may be connected to a nacelle boundary layer bleed compressor to bleed boundary layer air from a forward portion of the nacelle to reduce nacelle surface drag. The ECS may be provided with a wing boundary layer bleed means which uses a cooling air fan in the ECS to draw cooling air through the heat exchangers in the ECS pack from the boundary layer air from a forward portion of the aircraft's wing to reduce its surface drag.

Abstract: A system for preventing the sudden depressurization of a compartment in an aircraft from causing structural damage or damage to other critical aircraft components. The system includes a pivotable closure. Normally, this closure is latched across a passage between a pressurized compartment such as a passenger cabin and a dump such as the space between the cabin wall and the outer skin of the aircraft. In the event that pressure is suddenly lost in a second pressurized compartment such as a cargo hold beneath the floor of the passenger compartment, a pressure differential is created across a flap-type latch actuator carried by the closure. This rotates the actuator, disengaging an actuator-associated latch element from a fixedly mounted keeper and thereby allowing the closure to be swung to an open position by outrushing air. This makes the entire area of the passage to the dump available for the outflow of air.

Abstract: A reuseable panel for equalizing pressure between adjacent compartments includes a frame and a movable floor which is releasably sandwiched within the frame on three sides. When there is a sufficiently large pressure differential between the compartments, the three sides of the door are dislodged from the frame (blowout) thereby exposing an opening to allow the pressure between the compartments to equalize. In order to provide additional control over the pressure at which door blowout occurs, one end of a flexible strap is fixedly attached to the door while the other end is removably connected to an attachment bracket which is fixed to the frame. By adjusting (i) the configuration of the attachment bracket, (ii) the depth at which the door is sandwiched within the frame, (iii) the number of attachment brackets, (iv) the position of the attachment brackets, and (v) the side of the frame on which the attachment brackets are mounted, the pressure differential at which door blowout occurs can be adjusted.