WO2023019287A1 - Dust control - Google Patents

Dust control Download PDF

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Publication number
WO2023019287A1
WO2023019287A1 PCT/AU2022/050648 AU2022050648W WO2023019287A1 WO 2023019287 A1 WO2023019287 A1 WO 2023019287A1 AU 2022050648 W AU2022050648 W AU 2022050648W WO 2023019287 A1 WO2023019287 A1 WO 2023019287A1
Authority
WO
WIPO (PCT)
Prior art keywords
air
building
filters
pressure
outside
Prior art date
Application number
PCT/AU2022/050648
Other languages
French (fr)
Inventor
Melton Donald WHITE
Matthew James GEE
Steven Leslie SMITH
Yuri Barros CAMPOS
Original Assignee
Mideco Pty Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mideco Pty Ltd filed Critical Mideco Pty Ltd
Publication of WO2023019287A1 publication Critical patent/WO2023019287A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F8/00—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying
    • F24F8/10—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying by separation, e.g. by filtering
    • F24F8/108—Treatment, e.g. purification, of air supplied to human living or working spaces otherwise than by heating, cooling, humidifying or drying by separation, e.g. by filtering using dry filter elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/70—Control systems characterised by their outputs; Constructional details thereof
    • F24F11/72—Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/02—Ducting arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
    • F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/16—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by purification, e.g. by filtering; by sterilisation; by ozonisation
    • F24F3/167—Clean rooms, i.e. enclosed spaces in which a uniform flow of filtered air is distributed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/50—Control or safety arrangements characterised by user interfaces or communication
    • F24F11/52—Indication arrangements, e.g. displays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/0001—Control or safety arrangements for ventilation
    • F24F2011/0002—Control or safety arrangements for ventilation for admittance of outside air
    • F24F2011/0004—Control or safety arrangements for ventilation for admittance of outside air to create overpressure in a room
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2140/00—Control inputs relating to system states
    • F24F2140/10—Pressure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the invention relates to methods and apparatus for protecting building occupants from particulates.
  • PPE personal protective equipment
  • the present inventor has recognised that the dangers associated with airborne particulates can extend indoors.
  • the invention aims to protect building occupants from airborne particulates.
  • One aspect of the invention provides a system, for pressurizing one or more rooms of a building with filtered air to protect one or more occupants of the building from particulates, comprising one or more filters; one or more fans to move air through the one or more filters; an inside-air inlet upstream of, and to supply inside-air from inside the building to, the one or more filters; an outside-air inlet upstream of, and to supply outside-air from outside the building to, the one or more filters; a valve to restrict to flow through the outside-air inlet; and a control system configured to control the valve in response to feedback.
  • the valve may comprise a flap.
  • the system may comprise a filter (e.g. screen) arranged to filter the outside-air before the outside-air mixes with the inside-air.
  • the control system is configured to control the one or more fans.
  • Another aspect of the invention provides a system, for protecting one or more occupants of a building from particulates, comprising one or more filters; one or more fans to move air into one or more rooms of a building via the one or more filters to pressurise the one or more rooms; and a control system configured to control the fans in response to feedback.
  • the one or more rooms may together have a volume of at least 10 m 3 , e.g. at least 20 m 3 .
  • the system preferably has a capacity of at least 1000 m 3 /hr.
  • the system may be AC-powered, e.g. single-phase, 2-phase or 3-phase powered.
  • the system may comprise a HEPA filter.
  • the system comprises a pre-filter upstream of the HEPA filter.
  • the one or more fans are downstream of the one or more filters.
  • the system may be configured to aim for a target pressure of about 50 Pa.
  • the system preferably comprises an alarm system configured to alarm in response to the pressure falling below a threshold, e.g. below 20 Pa.
  • the system may be a transportable unit.
  • Another aspect of the invention provides a system comprising the system for protecting occupants; and a pressure sensor to provide the feedback.
  • Another aspect of the invention provides a method, of protecting occupants of a building from particulates, comprising installing the system for protecting occupants.
  • the method may comprise installing a conduit to convey air from the system towards the room.
  • Another aspect of the invention provides a building comprising the system for protecting occupants.
  • Figure 1 is a perspective view of a transportable unit
  • Figure 2 is a cross-section view of the transportable unit
  • Figure 3 is a perspective view of another air supply system
  • Figure 4 is cross-section view of another transportable unit
  • Figure 5 is a perspective view of three potential installations
  • Figure 6 is a plan view of the three potential installations.
  • Figure 7 is a cross-section view of another transportable unit.
  • the system 1 is a transportable unit comprising a tubular housing 3.
  • the housing 3 is metallic.
  • Stainless steel is a preferred material.
  • Galvanised sheet is another option.
  • the housing houses HEPA filter 5 and pre-filter 7.
  • a pre-filter is a filter coarser than, to protect, a downstream filter.
  • the filters 5, 7 are clamped in place inside the housing 3 between filter frame 9 and filter clamp 11 .
  • Other mounting arrangements are possible.
  • the HEPA filter 5 is preferably an H13 filter.
  • Fan 13 resides downstream of the filters 5, 7.
  • the fan 13 comprises a fan blade 13a and an electric motor 13b.
  • the fan is mounted via mounting bracket 15.
  • FIG. 1 This example of the unit 1 has a generally uniform rectangular profile along its horizontal length.
  • Figure 3 illustrates another example of a transportable unit T in which the cross-section varies down its vertical length from a rectangular profile upstream filtration section 3a to a fan unit downstream 3b.
  • Figure 3 also shows a hood 17 and conduit 19 fitted top and bottom to the transportable unit T.
  • the hood 17 is a peaked lid comprising inlets under its outside ends.
  • the lid is peaked so that water runs off.
  • Arranging the inlet(s) upward to draw in air reduces the intake of water.
  • Conduit 19 is an elbow configured to turn the vertically-directed air, coming from the fan module 3b, horizontally.
  • the conduit is spanned by a guard such as a mesh grill to block access to the fan.
  • the units 1 , T are examples of prefabricated transportable units that can be cost- efficiently manufactured, transported and installed.
  • the units are installed on or adjacent to a building and connected thereto to pressurise at least one room thereof.
  • the units 1 , T are supplied as parts of kits also comprising one or more (and preferably each) of sealant (e.g. silicone for sealing the wall penetration), a template for marking out the required penetration and sticky tape for holding the template in place.
  • sealant e.g. silicone for sealing the wall penetration
  • a template for marking out the required penetration and sticky tape for holding the template in place.
  • the unit preferably has one, and only one, power inlet (e.g. power lead) whereby only one onsite electrical connection is required to power the components of the transportable unit.
  • Preferred variants of the unit T incorporate a control system by which the fan 13 is controllable to maintain the pressure in the room.
  • the fan can be sped up and slowed down as necessary to maintain pressure as leakages about doorways and windows (etc) change from time to time.
  • Any convenient form of feedback system may be utilised.
  • the speed and current drawn by the motor 13b might be monitored to make inferences about the pressure delivered by the fan 13 or, more preferably, a dedicated pressure sensor is provided.
  • a dedicated pressure sensor is a simple and convenient means of maintaining pressure even as the filters 5, 7 are loaded with particulates.
  • the pressure sensor may be built in to the unit 1 . Alternatively, it may be remotely mounted and provide a feedback signal.
  • the feedback signal may be a wireless signal.
  • the control system is preferably configured to minimise reaction to transients such as the pressure drop associated with a door being opened, e.g. after a significant pressure drop a signal to change the fan speed might be delayed, e.g. by one minute, until a second pressure reading indicates that the pressure remains low.
  • the fans might be controlled based on historical data (e.g. data over the last five minutes) processed to ignore (or give less weight to) outlying pressure data.
  • the control system of the unit 1 preferably incorporates an alarm function to warn, e.g. warn the occupants of the room, of a malfunction.
  • the control system is configured to alarm in response to the pressure in the room falling below a predetermined threshold, e.g. in response to falling and remaining below a threshold for a delay period.
  • the delay period allows for temporary pressure drops associated with doors being momentarily opened.
  • the alarm could be an audible alarm, a visual alarm such as a simple LED light, or any other convenient means of alarming, such as a wireless signal.
  • the room pressure is data-logged over time.
  • the datalogging and/or alarm functions may be built into the transportable unit. Alternatively, the functions may be provided remotely separate from the unit 1 .
  • the control system is also configured to alarm when the filters 5, 7 are loaded to capacity.
  • This may be achieved with dedicated pressure sensors to provide an indication of the pressure drop across the filter 7, or inferences may be drawn based on the pressure sensor in the room and feedback from the motor 13b.
  • Figures 5 and 6 show three potential installations of an air supplying unit 1".
  • the unit 1" is akin to unit 1 although the downstream end is enlarged to define a plenum space pressurised by the fan 13.
  • the plenum space has a plurality of openings. In this case there are three openings: a front opening, a back opening and an end opening.
  • the unit 1" comprises a set of pieces complementary to the plurality of openings. In this example, the set comprises two impermeable panels 21 and outlet piece 2T. Components 21 , 2T are interchangeable to leave only a selected one of the three openings from the plenum open.
  • the unit 1" is fitted with a hood 17' at its inlet end and ducting 19' at its outlet end.
  • the ducting 19' may be telescopic.
  • the system 1 is configured to draw outside air in through the hood 17, filter that air and drive the filtered air into the room.
  • Other variants of the concept may be configured to recirculate the inside air in addition to or as an alternative to pressurisation.
  • Figure 7 schematically illustrates a system 101 configured to both recirculate inside air and supply filtered outside air to the room. Details disclosed in connection with the system 1 may be applied to variants of the system 101 and vice versa.
  • the system 101 comprises housing 103, filters 105, 107, a fan 113, an outside-air inlet 117, an outlet 119 and an inside-air inlet 123.
  • the system further comprises an inlet plenum 125 into which air flows from the inlets 117, 123 en route to the filters 105, 107. Filtered air is ducted from the outlet 119 into the room wherein it is preferably released in proximity to the ceiling.
  • the outside-air inlet 117 is equipped with a valve 117b, 117c comprising a flap 117b and an actuator 117c configured to move the flap.
  • the inlet 117 is further equipped with a pre-filter 117a to filter the outside air en route into the plenum 125.
  • the system 101 further comprises a controller 129 to control the valve 117b, 117c.
  • the controller is responsive to a remote pressure sensor 127 mounted inside the room.
  • the sensor 127 may be wirelessly connected to the controller 129.
  • the inside-air inlet 123 is connected to the interior of the building via a return line and a return air grill.
  • the return line is configured to tolerate negative pressure.
  • Rigid pipe, such as PVC pipe is preferred.
  • the prototypes have been tested with 10” (250mm) diameter pipe up to 5m long. Whilst PVC pipe is not conventionally used in HVAC applications, the inventors have found it to be a robust utilitarian option that is easy to work with and otherwise well adapted to challenging environments such as dusty mine sites.
  • Preferred implementations of the system 101 are configured to hold the room at about 35 pascal above atmospheric pressure. Experimentation has shown that with convenient flow rates and a return path of the type described, the pressure drop along the return path is more than about 35 pascal whereby the plenum space 125 is at a slightly negative pressure.
  • the rate at which outside air is drawn into the system can be controlled so as to replace the air leaking from the room (e.g. via door and window seals) to maintain pressure.
  • the restriction through the valve is controlled in positive relation to the pressure in the room, e.g. as the pressure in the room rises towards the target pressure above atmospheric pressure, the valve may be closed (so as to reduce the valve opening) and thereby increase the restriction to flow through the inlet 117.
  • Some variants of the valve may be fully closable, e.g. for a short period of time if the pressure sensor 127 suggests that the pressure within the room has risen above the target pressure.
  • the controller 129 also controls the fan 1 13. Potentially the controller 129 may coordinate the control of the fan 1 13 and the valve 1 17b, 1 17c, e.g. so as to maintain a flow rate through the inlet 1 17 (to maintain a rate at which fresh air is supplied), through the inlet 123 (to maintain a recirculation rate) or through the outlet 1 19 (to maintain a delivery rate).
  • an indication of the flow rate through the fan may be inferred from the motor speed and current draw, and the relationship between the outside air ingress rate and valve position may be calibrated, e.g. in the form of a lookup table stored within the controller 129.
  • the fan speed and valve opening are alternately incremented in response to an indication that the in-room pressure is below the target pressure.
  • the incrementation steps may be separated by pauses and an alarm signal may be issued if, after a pre-determined period of time, the target pressure is not reached.
  • the valve opening and fan speed may be alternately decremented if the pressure rises above the target pressure.
  • the pressure differential would immediately disappear as air rushed out of the door.
  • the system 101 would seek to increase pressure (e.g. via the alternate incrementation steps), then if the system 101 cannot rebuild pressure (e.g. because the door has been left open) the alarm would sound.
  • the pressure being below the target pressure is regarded as a safety issue that may be associated with the ingress of dust so the logic might seek to build pressure more rapidly than it seeks to lower pressure.
  • the increments may be larger in magnitude than the decrements.

Abstract

A system (for protecting occupants of a building from particulates) comprising one or more filters, one or more fans (to move air into at least one room of a building via the one or more filters to pressurise the at least one room), and a control system configured to control the fans in response to feedback.

Description

DUST CONTROL
FIELD
The invention relates to methods and apparatus for protecting building occupants from particulates.
BACKGROUND
Airborne particulates are hazardous to health. In various dusty environments, personal protective equipment (PPE) is mandated before stepping outdoors.
The present inventor has recognised that the dangers associated with airborne particulates can extend indoors.
Accordingly, the invention aims to protect building occupants from airborne particulates.
SUMMARY
One aspect of the invention provides a system, for pressurizing one or more rooms of a building with filtered air to protect one or more occupants of the building from particulates, comprising one or more filters; one or more fans to move air through the one or more filters; an inside-air inlet upstream of, and to supply inside-air from inside the building to, the one or more filters; an outside-air inlet upstream of, and to supply outside-air from outside the building to, the one or more filters; a valve to restrict to flow through the outside-air inlet; and a control system configured to control the valve in response to feedback.
The valve may comprise a flap. The system may comprise a filter (e.g. screen) arranged to filter the outside-air before the outside-air mixes with the inside-air. Preferably the control system is configured to control the one or more fans.
Another aspect of the invention provides a system, for protecting one or more occupants of a building from particulates, comprising one or more filters; one or more fans to move air into one or more rooms of a building via the one or more filters to pressurise the one or more rooms; and a control system configured to control the fans in response to feedback.
The one or more rooms may together have a volume of at least 10 m3, e.g. at least 20 m3. The system preferably has a capacity of at least 1000 m3/hr. The system may be AC-powered, e.g. single-phase, 2-phase or 3-phase powered.
The system may comprise a HEPA filter. Preferably, the system comprises a pre-filter upstream of the HEPA filter.
Preferably, the one or more fans are downstream of the one or more filters.
The system may be configured to aim for a target pressure of about 50 Pa. The system preferably comprises an alarm system configured to alarm in response to the pressure falling below a threshold, e.g. below 20 Pa.
The system may be a transportable unit.
Another aspect of the invention provides a system comprising the system for protecting occupants; and a pressure sensor to provide the feedback. Another aspect of the invention provides a method, of protecting occupants of a building from particulates, comprising installing the system for protecting occupants.
The method may comprise installing a conduit to convey air from the system towards the room.
Another aspect of the invention provides a building comprising the system for protecting occupants.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a perspective view of a transportable unit;
Figure 2 is a cross-section view of the transportable unit;
Figure 3 is a perspective view of another air supply system;
Figure 4 is cross-section view of another transportable unit;
Figure 5 is a perspective view of three potential installations;
Figure 6 is a plan view of the three potential installations; and
Figure 7 is a cross-section view of another transportable unit.
DESCRIPTION OF EMBODIMENTS
The system 1 is a transportable unit comprising a tubular housing 3. In this example, the housing 3 is metallic. Stainless steel is a preferred material. Galvanised sheet is another option. The housing houses HEPA filter 5 and pre-filter 7. A pre-filter is a filter coarser than, to protect, a downstream filter. The filters 5, 7 are clamped in place inside the housing 3 between filter frame 9 and filter clamp 11 . Other mounting arrangements are possible. The HEPA filter 5 is preferably an H13 filter. Fan 13 resides downstream of the filters 5, 7. In this example, the fan 13 comprises a fan blade 13a and an electric motor 13b. The fan is mounted via mounting bracket 15.
This example of the unit 1 has a generally uniform rectangular profile along its horizontal length. Figure 3 illustrates another example of a transportable unit T in which the cross-section varies down its vertical length from a rectangular profile upstream filtration section 3a to a fan unit downstream 3b.
Figure 3 also shows a hood 17 and conduit 19 fitted top and bottom to the transportable unit T.
The hood 17 is a peaked lid comprising inlets under its outside ends. The lid is peaked so that water runs off. Arranging the inlet(s) upward to draw in air reduces the intake of water. There is mesh across the air inlets to prevent birds nesting inside. Conduit 19 is an elbow configured to turn the vertically-directed air, coming from the fan module 3b, horizontally. Preferably, the conduit is spanned by a guard such as a mesh grill to block access to the fan.
The units 1 , T are examples of prefabricated transportable units that can be cost- efficiently manufactured, transported and installed. The units are installed on or adjacent to a building and connected thereto to pressurise at least one room thereof. Preferably the units 1 , T are supplied as parts of kits also comprising one or more (and preferably each) of sealant (e.g. silicone for sealing the wall penetration), a template for marking out the required penetration and sticky tape for holding the template in place. The unit preferably has one, and only one, power inlet (e.g. power lead) whereby only one onsite electrical connection is required to power the components of the transportable unit.
Preferred variants of the unit T incorporate a control system by which the fan 13 is controllable to maintain the pressure in the room. In this way, the fan can be sped up and slowed down as necessary to maintain pressure as leakages about doorways and windows (etc) change from time to time. Any convenient form of feedback system may be utilised. By way of example, the speed and current drawn by the motor 13b might be monitored to make inferences about the pressure delivered by the fan 13 or, more preferably, a dedicated pressure sensor is provided. Using a dedicated pressure sensor is a simple and convenient means of maintaining pressure even as the filters 5, 7 are loaded with particulates. The pressure sensor may be built in to the unit 1 . Alternatively, it may be remotely mounted and provide a feedback signal. The feedback signal may be a wireless signal.
The control system is preferably configured to minimise reaction to transients such as the pressure drop associated with a door being opened, e.g. after a significant pressure drop a signal to change the fan speed might be delayed, e.g. by one minute, until a second pressure reading indicates that the pressure remains low. In one implementation, the fans might be controlled based on historical data (e.g. data over the last five minutes) processed to ignore (or give less weight to) outlying pressure data.
The control system of the unit 1 preferably incorporates an alarm function to warn, e.g. warn the occupants of the room, of a malfunction. Preferably, the control system is configured to alarm in response to the pressure in the room falling below a predetermined threshold, e.g. in response to falling and remaining below a threshold for a delay period. The delay period allows for temporary pressure drops associated with doors being momentarily opened. The alarm could be an audible alarm, a visual alarm such as a simple LED light, or any other convenient means of alarming, such as a wireless signal.
In preferred implementations, the room pressure is data-logged over time. The datalogging and/or alarm functions may be built into the transportable unit. Alternatively, the functions may be provided remotely separate from the unit 1 .
Preferably, the control system is also configured to alarm when the filters 5, 7 are loaded to capacity. This may be achieved with dedicated pressure sensors to provide an indication of the pressure drop across the filter 7, or inferences may be drawn based on the pressure sensor in the room and feedback from the motor 13b. Figures 5 and 6 show three potential installations of an air supplying unit 1". The unit 1" is akin to unit 1 although the downstream end is enlarged to define a plenum space pressurised by the fan 13. The plenum space has a plurality of openings. In this case there are three openings: a front opening, a back opening and an end opening. The unit 1" comprises a set of pieces complementary to the plurality of openings. In this example, the set comprises two impermeable panels 21 and outlet piece 2T. Components 21 , 2T are interchangeable to leave only a selected one of the three openings from the plenum open.
In the illustrated installations, the unit 1" is fitted with a hood 17' at its inlet end and ducting 19' at its outlet end. The ducting 19' may be telescopic.
The system 1 is configured to draw outside air in through the hood 17, filter that air and drive the filtered air into the room. Other variants of the concept may be configured to recirculate the inside air in addition to or as an alternative to pressurisation.
Figure 7 schematically illustrates a system 101 configured to both recirculate inside air and supply filtered outside air to the room. Details disclosed in connection with the system 1 may be applied to variants of the system 101 and vice versa.
The system 101 comprises housing 103, filters 105, 107, a fan 113, an outside-air inlet 117, an outlet 119 and an inside-air inlet 123. The system further comprises an inlet plenum 125 into which air flows from the inlets 117, 123 en route to the filters 105, 107. Filtered air is ducted from the outlet 119 into the room wherein it is preferably released in proximity to the ceiling.
The outside-air inlet 117 is equipped with a valve 117b, 117c comprising a flap 117b and an actuator 117c configured to move the flap. The inlet 117 is further equipped with a pre-filter 117a to filter the outside air en route into the plenum 125.
The system 101 further comprises a controller 129 to control the valve 117b, 117c. In this example, the controller is responsive to a remote pressure sensor 127 mounted inside the room. The sensor 127 may be wirelessly connected to the controller 129. The inside-air inlet 123 is connected to the interior of the building via a return line and a return air grill. In this example of the concept, the return line is configured to tolerate negative pressure. Rigid pipe, such as PVC pipe, is preferred. By way of example, the prototypes have been tested with 10” (250mm) diameter pipe up to 5m long. Whilst PVC pipe is not conventionally used in HVAC applications, the inventors have found it to be a robust utilitarian option that is easy to work with and otherwise well adapted to challenging environments such as dusty mine sites.
Preferred implementations of the system 101 are configured to hold the room at about 35 pascal above atmospheric pressure. Experimentation has shown that with convenient flow rates and a return path of the type described, the pressure drop along the return path is more than about 35 pascal whereby the plenum space 125 is at a slightly negative pressure.
Given this negative pressure in the plenum, by controlling the valve 1 17b, 117c the rate at which outside air is drawn into the system can be controlled so as to replace the air leaking from the room (e.g. via door and window seals) to maintain pressure. Accordingly, in the illustrated implementation, it is preferred that the restriction through the valve is controlled in positive relation to the pressure in the room, e.g. as the pressure in the room rises towards the target pressure above atmospheric pressure, the valve may be closed (so as to reduce the valve opening) and thereby increase the restriction to flow through the inlet 117. Some variants of the valve may be fully closable, e.g. for a short period of time if the pressure sensor 127 suggests that the pressure within the room has risen above the target pressure.
In this example, the controller 129 also controls the fan 1 13. Potentially the controller 129 may coordinate the control of the fan 1 13 and the valve 1 17b, 1 17c, e.g. so as to maintain a flow rate through the inlet 1 17 (to maintain a rate at which fresh air is supplied), through the inlet 123 (to maintain a recirculation rate) or through the outlet 1 19 (to maintain a delivery rate). In one implementation, an indication of the flow rate through the fan may be inferred from the motor speed and current draw, and the relationship between the outside air ingress rate and valve position may be calibrated, e.g. in the form of a lookup table stored within the controller 129. In a preferred implementation, the fan speed and valve opening are alternately incremented in response to an indication that the in-room pressure is below the target pressure. The incrementation steps may be separated by pauses and an alarm signal may be issued if, after a pre-determined period of time, the target pressure is not reached. Similarly the valve opening and fan speed may be alternately decremented if the pressure rises above the target pressure.
By way of example, if a door is opened to connect the pressurised room(s) to atmosphere, the pressure differential would immediately disappear as air rushed out of the door. In response to that pressure drop the system 101 would seek to increase pressure (e.g. via the alternate incrementation steps), then if the system 101 cannot rebuild pressure (e.g. because the door has been left open) the alarm would sound.
If the system 101 had taken steps to build pressure and then the door was closed, the pressure within the room would suddenly rise, immediately triggering a response from the system 101 , e.g. by alternately decrementing the fan speed and valve opening.
There may be an asymmetry in the response to under and over a pressure event.
The pressure being below the target pressure is regarded as a safety issue that may be associated with the ingress of dust so the logic might seek to build pressure more rapidly than it seeks to lower pressure. By way of example, the increments may be larger in magnitude than the decrements. By slowly reducing the fan speed and/or valve opening to slowly approach the target pressure from above, a more efficient steady state, at which the fan is consuming less energy, can be reached.
Other control strategies are possible, e.g. instead of the alternate incrementations, the fan speed and valve opening might be continuously variable. For the avoidance of doubt ‘continuously variable’ is used herein to refer to smooth acceleration as opposed to stepped acceleration. Digital control that results in many imperceptible steps is an example of continuous variable control as the wording is used herein.
The invention is not limited to the examples discussed herein. Rather, the invention is defined by the claims. The term "comprises" and its grammatical variants has a meaning that is determined by the context in which it appears. Accordingly, the term should not be interpreted exhaustively unless the context dictates so.

Claims

1 . A system, for pressurizing one or more rooms of a building with filtered air to protect one or more occupants of the building from particulates, comprising one or more filters; one or more fans to move air through the one or more filters; an inside-air inlet upstream of, and to supply inside-air from inside the building to, the one or more filters; an outside-air inlet upstream of, and to supply outside-air from outside the building to, the one or more filters; a valve to restrict to flow through the outside-air inlet; and a control system configured to control the valve in response to feedback.
2. The system of claim 1 wherein the valve comprises a flap.
3. The system of claim 1 or 2 comprises a filter arranged to filter the outside-air before the outside-air mixes with the inside-air.
4. The system of any one of claims 1 to 3 wherein the control system is configured to control the one or more fans.
5. A system, for protecting one or more occupants of a building from particulates, comprising one or more filters; one or more fans to move air into one or more rooms of a building via the one or more filters to pressurise the one or more rooms; and a control system configured to control the fans in response to feedback.
6. The system of any one of claims 1 to 5 wherein the one or more rooms together have a volume of at least 10 m3.
7. The system of any one of claims 1 to 5 wherein the one or more rooms together have a volume of at least 20 m3.
8. The system of any one of claims 1 to 7 being AC-powered.
9. The system of any one of claims 1 to 8 being 3-phase powered.
10. The system of any one of claims 1 to 9 comprising a HEPA filter.
1 1 . The system of any one of claims 1 to 10 wherein the one or more fans are downstream of the one or more filters.
12. The system of any one of claims 1 to 11 wherein the system is configured to aim for a target pressure of about 50 Pa.
13. The system of any one of claims 1 to 12 comprising an alarm system configured to alarm in response to a pressure falling below a threshold.
14. The system of claim 13 wherein the threshold is 20 Pa.
15. The system of any one of claims 1 to 14 being a transportable unit.
16. A system comprising the system of any one of claims 1 to 15; and a pressure sensor to provide the feedback.
17. A method, of protecting occupants of a building from particulates, comprising installing the system of any one of claims 1 to 16.
18. The method of claim 17 comprising installing a conduit to convey air from the system towards the room.
19. A building comprising the system of any one of claims 1 to 16.
PCT/AU2022/050648 2021-08-19 2022-06-24 Dust control WO2023019287A1 (en)

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Citations (5)

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US9518748B2 (en) * 2009-08-16 2016-12-13 G-Con Manufacturing Inc. Modular, self-contained, mobile clean room
US20190086116A1 (en) * 2013-05-09 2019-03-21 Pathian Incorporated Building pressure control
WO2019194333A1 (en) * 2018-04-05 2019-10-10 (주)화이컴 Clean air supplier, support plate for supporting clean air supplier, window frame on which clean air supplier is installed, and plug for blocking bored hole formed in window frame
KR20210034223A (en) * 2019-09-20 2021-03-30 정 흠 한 Air condensing system for preventing inflow of out air
CN113124491A (en) * 2020-01-16 2021-07-16 苏州卡洛尔净化科技有限公司 Intelligent dehumidifying fresh air system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9518748B2 (en) * 2009-08-16 2016-12-13 G-Con Manufacturing Inc. Modular, self-contained, mobile clean room
US20190086116A1 (en) * 2013-05-09 2019-03-21 Pathian Incorporated Building pressure control
WO2019194333A1 (en) * 2018-04-05 2019-10-10 (주)화이컴 Clean air supplier, support plate for supporting clean air supplier, window frame on which clean air supplier is installed, and plug for blocking bored hole formed in window frame
KR20210034223A (en) * 2019-09-20 2021-03-30 정 흠 한 Air condensing system for preventing inflow of out air
CN113124491A (en) * 2020-01-16 2021-07-16 苏州卡洛尔净化科技有限公司 Intelligent dehumidifying fresh air system

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