A loss-in-weight feeder anti-bridging device based on powder fluidization technology

Abstract

This invention discloses an anti-bridging device for a loss-in-weight feeder based on powder fluidization technology, relating to the field of feeder technology. The device includes: a loss-in-weight feeder comprising a main chamber and a hopper located below the main chamber; an anti-bridging component embedded in the side wall of the loss-in-weight feeder; multiple aerators distributed in the main chamber, each aerator receiving air from an air pipe via a nozzle, and the air pipe's on / off state controlled by a solenoid valve; and an exhaust component located at the top of the main chamber. Both the solenoid valve and the exhaust component are controlled by a controller, which adapts the exhaust parameters of the exhaust component to the aeration parameters of the aerators. This device, utilizing the anti-bridging component and aerators in conjunction, enables both active and passive anti-bridging mechanisms.

Description

Technical Field

[0001] This invention relates to the field of feeder technology, and more specifically to a loss-in-weight feeder anti-bridging device based on powder fluidization technology. Background Technology

[0002] In the field of powder processing and feeding, loss-in-weight feeders are widely used in the food, pharmaceutical and chemical industries due to their high-precision metering characteristics.

[0003] However, powder materials are prone to bridging in the silo due to interparticle friction, electrostatic adsorption, or stickiness, which can lead to interruption of feeding or flow fluctuations, seriously affecting the continuity of feeding and metering accuracy.

[0004] Traditional solutions to bridging problems primarily rely on mechanical mixing devices. These devices use horizontal or vertical agitators installed in the hopper to disrupt the powder structure through mechanical disturbance. However, these devices have significant drawbacks: the mixing mechanism is complex and bulky, increasing the overall weight of the equipment and requiring larger capacity weighing sensors, directly leading to decreased measurement accuracy. Furthermore, the mechanical vibration during mixing interferes with the static balance of the weighing system, causing measurement errors. More importantly, the agitator's disturbance to the powder is non-directional, offering limited effectiveness in breaking up bridging structures (such as sidewall adhesion or bottom accumulation) formed by loose or sticky powders. Bridging still occurs with a small probability, failing to meet the demands for high-precision and high-stability feeding.

[0005] In recent years, powder fluidization technology, which suspends powder particles and generates shear force through gas injection, has gradually become a potential alternative to mechanical stirring. However, existing fluidization anti-bridging devices still have technical bottlenecks: First, the aerator arrangement lacks directionality, and the airflow acts dispersedly on the main chamber as a whole, resulting in weak ability to destroy local bridging structures in areas prone to bridging; second, the exhaust system is mostly a fixed design, which cannot dynamically adjust the exhaust rate according to aeration parameters, easily leading to powder backfluidization or uneven fluidization under high pressure differential conditions; third, the active anti-bridging component has a single function and limited effectiveness in treating sticky powders or heavily bridging materials.

[0006] Therefore, it is necessary to provide a loss-in-weight feeder anti-bridging device based on powder fluidization technology to solve the above problems. Summary of the Invention

[0007] To solve the above problems, the present invention provides the following technical solution: a loss-in-weight feeder anti-bridging device based on powder fluidization technology, comprising: a loss-in-weight feeder, including a main bin and a hopper located below the main bin; and an anti-bridging component embedded in the side wall of the loss-in-weight feeder;

[0008] Multiple aerators are distributed in the main chamber. Each aerator is supplied with air through an air pipe via an air nozzle, and the air pipe is controlled by a solenoid valve. An exhaust assembly is located at the top of the main chamber. Both the solenoid valve and the exhaust assembly are controlled by a controller, which can adjust the exhaust parameters of the exhaust assembly to match the aeration parameters of the aerators.

[0009] Preferably, the aerator is configured to aerate toward the anti-bridging assembly in order to achieve passive arch breaking using the anti-bridging assembly.

[0010] Preferably, the hopper is U-shaped or hemispherical, and two aerators are symmetrically arranged in the hopper.

[0011] Preferably, the exhaust assembly includes: an exhaust pipe, with its bottom connected to the main chamber and its top connected to an air extraction pipe, the air extraction pipe being connected to a three-way valve, the three-way valve being connected to a self-draining pipe and a suction pump respectively; a screen, fixed in the exhaust pipe; the controller is able to control the three-way valve to enable the exhaust pipe to achieve adaptive exhaust using the self-draining pipe, or to use the suction pump to perform exhaust adapted to the aeration parameters of the aerator.

[0012] Preferably, a float plate is slidably disposed inside the exhaust pipe below the barrier net, and a floating spring is connected between the float plate and the exhaust pipe; the float plate has multiple through holes, and an elastic conical hole is embedded in the through hole, the elastic conical hole gradually expanding from bottom to top; an expanding cylinder corresponding to the elastic conical hole is fixed at the bottom of the barrier net, and the side of the expanding cylinder has a side hole.

[0013] Preferably, the side wall of the loss-in-weight feeder has stepped through holes; the anti-bridging assembly includes: a base, which is correspondingly embedded in the stepped through holes, and a sealing ring and a sealing ring are provided between the base and the stepped through holes, and a groove is provided at one end of the base facing the inner side of the loss-in-weight feeder; a composite membrane, which is connected to the groove opening of the groove and together with the groove forms a chamber; a pad, which is embedded in the groove, and a support is provided between the pad and the composite membrane; and an air supply head, which is used to supply air to the chamber or extract air from the chamber.

[0014] Preferably, the support member is a support spring.

[0015] Preferably, the support is a fixed-point support assembly, which includes: an inner cylinder, one end of which is fixed to the pad, and the other end of which is slidably fitted with an outer cylinder, forming a buffer connection between the outer cylinder and the inner cylinder; and a bracket, which is fixed to the outer cylinder and has multiple support plates.

[0016] Preferably, the composite membrane includes a contact layer, an antistatic layer, a skeleton layer, an airtight layer, and a permeation column that are sequentially pasted from the side closest to the inside of the loss-in-weight feeder outwards, with the permeation column protruding from the contact layer and forming a protrusion.

[0017] Preferably, the controller is further configured to: when actively breaking the arch using the anti-bridging component, control the air supply head to first pulse-charge the chamber with air, then continuously apply pressure, and finally rapidly evacuate the air.

[0018] Compared with the prior art, the present invention provides a loss-in-weight feeder anti-bridging device based on powder fluidization technology, which has the following beneficial effects:

[0019] In this invention, gas is injected into the powder through an aerator in the main chamber. The fluidization effect suspends some powder particles and generates shear force, thus disrupting the static structure of bridging. This method is particularly suitable for mild bridging scenarios. In addition, the anti-bridging component can actively intervene through a combination of "pulse inflation → continuous pressure → rapid degassing" to ensure continuous feeding.

[0020] In this invention, the controller dynamically adjusts the exhaust parameters of the exhaust assembly based on the aeration parameters of the aerator to avoid excessively high or fluctuating air pressure in the main chamber. When the aeration volume increases, the controller switches the three-way valve to start the suction pump for active exhaust, ensuring that the exhaust rate matches the aeration flow rate; in low-pressure differential scenarios, it uses self-exhausting pipes for adaptive exhaust to reduce energy consumption.

[0021] In this invention, the composite membrane of the anti-bridging component adopts a layered design. The contact layer has low friction and anti-adhesion, the antistatic layer avoids the electrostatic adsorption of powder, and the skeleton layer provides mechanical strength to ensure stable deformation under air pressure. The seepage column protrudes from the contact layer to form a protrusion and is embedded in the powder layer to enhance local disturbance. Attached Figure Description

[0022] Figure 1 A three-dimensional structural schematic diagram of an anti-bridging device for a loss-in-weight feeder based on powder fluidization technology;

[0023] Figure 2 This is a plan view of the exhaust component in an anti-bridging device for a loss-in-weight feeder based on powder fluidization technology.

[0024] Figure 3 This is a plan view of an anti-bridging component in a loss-in-weight feeder based on powder fluidization technology. Figure 1 ;

[0025] Figure 4 This is a plan view of an anti-bridging component in a loss-in-weight feeder based on powder fluidization technology. Figure 2 ;

[0026] Figure 5 for Figure 4 Enlarged structural diagram of the central fixed-point support component;

[0027] Figure 6 This is a schematic diagram of the planar structure of the composite membrane in an anti-bridging device for a loss-in-weight feeder based on powder fluidization technology.

[0028] In the diagram: 1. Air nozzle; 2. Aerator; 3. Loss-in-weight feeder; 4. Air pipe; 5. Solenoid valve; 6. Pressure regulating valve; 7. Controller; 8. Exhaust assembly; 9. Anti-bridging assembly; 81. Exhaust pipe; 82. Suction pipe; 83. Barrier net; 84. Expanding cylinder; 85. Float plate; 86. Floating spring; 87. Elastic conical hole; 91. Base; 92. Sealing ring gasket; 93. Composite membrane; 94. Pad plate; 95. Fixed-point support assembly; 96. Support spring; 97. Air supply head; 951. Support plate; 952. Bracket; 953. Outer cylinder; 954. Inner cylinder; 931. Contact layer; 932. Antistatic layer; 933. Skeleton layer; 934. Airtight layer; 935. Percolation column. Detailed Implementation

[0029] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0030] Example 1: Please refer to Figures 1-3 , Figure 6 In this embodiment of the invention, an anti-bridging device for a loss-in-weight feeder based on powder fluidization technology is provided, comprising: a loss-in-weight feeder 3, including a main chamber and a hopper located below the main chamber; an anti-bridging component 9, embedded in the side wall of the loss-in-weight feeder 3; multiple aerators 2, distributed in the main chamber, the aerators 2 being supplied with air by air pipes 4 through air nozzles 1 on them, and the opening and closing of the air pipes 4 being controlled by a solenoid valve 5, the solenoid valve 5 being connected to a pressure regulating valve 6; an exhaust component 8, disposed at the top of the main chamber; both the solenoid valve 5 and the exhaust component 8 are controlled by a controller 7, the controller 7 being able to control the exhaust parameters of the exhaust component 8 to be adapted to the aeration parameters of the aerators 2.

[0031] In this embodiment, gas is sprayed into the powder in the main chamber by multiple aerators 2 distributed in the main chamber. Some powder particles begin to be suspended in the airflow, achieving a fluidization effect. Furthermore, the airflow generates shear force between the powder particles, which, together with the anti-bridging component 9, destroys the static structure of powder bridging, thus achieving anti-bridging.

[0032] In addition, the exhaust assembly 8 at the top of the main chamber discharges excess gas through the exhaust pipe 81. The controller 7 can dynamically adjust the exhaust parameters (such as exhaust rate and exhaust volume) of the exhaust assembly 8 according to the aeration parameters (such as gas flow rate, pressure, or frequency) of the aerator 2. For example, when the aerator 2 increases the aeration volume, the controller 7 will control the exhaust assembly 8 to speed up the exhaust to avoid excessive air pressure in the main chamber.

[0033] Furthermore, the aerator 2 is configured to aerate toward the anti-bridging assembly 9 in order to achieve passive arch breaking using the anti-bridging assembly 9.

[0034] It should be explained that the aerator 2 sprays gas towards the anti-bridging component 9, and the airflow can act on the powder area near the anti-bridging component 9. The directional airflow can destroy the powder bonding structure in this area. This process does not require active control of the anti-bridging component 9; it can be triggered simply by the conventional fluidization operation of the aerator 2, which is a form of "passive arch breaking." When the degree of powder bridging is relatively mild, the directional airflow is sufficient to destroy the bridging structure.

[0035] In addition, aerator 2 is also known as air stone or air-dispersing stone. It is made of high-quality white fused alumina and brown fused alumina, and is sintered at high temperature (1300 degrees Celsius). It is sturdy and durable, and has good air dispersion. It is commonly used in aeration, oxygenation and mixing operations in sewage treatment plants.

[0036] In addition, the anti-bridging component 9 can be installed at the location where bridging is likely to occur.

[0037] In this embodiment, the silo is U-shaped or hemispherical, and two aerators 2 are symmetrically arranged in the silo.

[0038] The bottom structure of U-shaped or hemispherical silos can reduce dead zones for material accumulation. The bottom of a U-shaped silo is relatively flat, which is suitable for powder to slide down naturally; the bottom of a hemispherical silo is rounded, which is suitable for viscous powders or materials that are prone to caking, and the rounded structure reduces the adhesion between the powder and the silo wall.

[0039] Two aerators 2 are symmetrically arranged in the silo to inject gas into the silo. The symmetrical layout allows the airflow to form convection or uniform coverage within the silo, avoiding bridging caused by insufficient local fluidization. In addition, both the aerators 2 in the silo and the aerators 2 in the main silo are controlled by a controller 7. When the aerators 2 in the main silo start fluidization, the aerators 2 in the silo can be selected to work synchronously to ensure continuous fluidization during the powder conveying process from the main silo to the silo.

[0040] In this embodiment, the exhaust assembly 8 includes: an exhaust pipe 81, with its bottom connected to the main chamber and its top connected to an extraction pipe 82, the extraction pipe 82 being connected to a three-way valve, the three-way valve being connected to a self-draining pipe and a suction pump respectively; a screen 83, fixed in the exhaust pipe 81; the controller 7 can control the three-way valve to enable the exhaust pipe 81 to achieve adaptive exhaust using the self-draining pipe, or to use the suction pump to exhaust in accordance with the aeration parameters of the aerator 2.

[0041] In this embodiment, when the aeration volume of aerator 2 is large (such as pulse aeration or high flow condition), controller 7 switches the three-way valve to allow the gas to be actively extracted through the suction pipe 82 → suction pump, ensuring that the exhaust rate is synchronized with the aeration parameters (such as flow rate and pressure) and avoiding excessively high air pressure in the main chamber.

[0042] Among them, the net 83 fixed in the exhaust pipe 81 can intercept powder particles that may be carried in the main compartment.

[0043] The three-way valve can be an electric three-way ball valve or a pneumatic three-way butterfly valve.

[0044] The suction pump can be a centrifugal suction pump or a vacuum pump.

[0045] In this embodiment, a float plate 85 is slidably disposed inside the exhaust pipe 81 below the barrier net 83, and a floating spring 86 is connected between the float plate 85 and the exhaust pipe 81; the float plate 85 has multiple through holes, and an elastic conical hole 87 is embedded in the through holes, and the elastic conical hole 87 gradually expands from bottom to top; the bottom of the barrier net 83 is fixed with an expanding cylinder 84 corresponding to the elastic conical hole 87, and the side of the expanding cylinder 84 has a side hole.

[0046] The float plate 85 is suspended inside the exhaust pipe 81 by a floating spring 86 and is located below the screen 83. When gas in the main chamber enters the exhaust pipe 81, the float plate 85 floats up and down due to the airflow, and the elastic conical hole 87 (narrower at the bottom and wider at the top) on it can initially restrict the passage of dust particles. When the aerator 2 starts high-flow aeration, the float plate 85 moves upward, and the elastic conical hole 87 expands to ensure smooth exhaust.

[0047] In this embodiment, the side wall of the loss-in-weight feeder 3 is provided with a stepped through hole; the anti-bridging component 9 includes: a base 91, which is correspondingly embedded in the stepped through hole, and a sealing ring gasket 92 and a sealing ring are provided between the base 91 and the stepped through hole, and a groove is provided at one end of the base 91 facing the inner side of the loss-in-weight feeder 3; a composite membrane 93, which is connected to the groove opening of the groove and together with the groove forms a chamber; a pad 94, which is embedded in the groove, and a support is provided between the pad 94 and the composite membrane 93; and an air supply head 97, which is used to supply air to the chamber or extract air from the chamber.

[0048] The controller 7 is further configured to: when the anti-bridging component 9 is used to actively break the arch, control the air supply head 97 to first pulse-charge the chamber with air, then continuously apply pressure, and finally quickly evacuate the air.

[0049] The gas supply head 97 is connected to the chamber, and the air pressure inside the chamber is changed by inflating or deflating. When active arch breaking is required, the controller 7 controls the gas supply head 97 in the sequence of "pulse inflation → continuous pressure → rapid deflating". Specifically, high-pressure gas is rapidly injected into the chamber, causing the composite membrane 93 to expand instantaneously, applying an impact force to the adjacent powder bridging area and destroying the static structure of the bridging (such as the friction and adhesion between powders). Afterward, the air pressure inside the chamber is maintained, keeping the composite membrane 93 in an expanded state, continuously squeezing the bridging area to prevent the bridging from reforming (especially suitable for sticky powders or loose bridging). Finally, the gas in the chamber is suddenly deflated, and the composite membrane 93 quickly retracts, generating negative pressure or mechanical vibration, further disturbing the powder layer and ensuring complete destruction of the bridging.

[0050] In this embodiment, the support component is a support spring 96. The support spring 96 connects the pad 94 and the composite membrane 93. Its core function is to maintain the initial shape of the composite membrane 93 and adapt to air pressure-driven deformation. Specifically, when the air supply head 97 inflates the chamber, the air pressure inside the chamber increases, and the composite membrane 93 expands outward (inside the feeder) under pressure. At this time, the support spring 96 is stretched, providing a reverse elastic force to prevent the composite membrane 93 from being damaged due to excessive stretching. Simultaneously, the spring's compression is proportional to the air pressure, ensuring that the deformation range of the composite membrane 93 is controllable. When the air supply head 97 deflates, the air pressure inside the chamber drops sharply, and the composite membrane 93 needs to retract to its initial shape. The elastic potential energy of the support spring 96 is released, pushing the composite membrane 93 to quickly reset. Furthermore, it prevents the composite membrane 93 from collapsing or adhering to the tank due to excessively low air pressure, thus affecting the response speed of the next arch-breaking action.

[0051] The composite membrane 93 includes a contact layer 931, an antistatic layer 932, a skeleton layer 933, an airtight layer 934, and a permeation column 935 that runs through each layer, which are sequentially pasted outward from the side closest to the inside of the loss-in-weight feeder 3. The permeation column 935 protrudes from the contact layer 931 and forms a protrusion.

[0052] The contact layer 931 is in direct contact with the powder and must have low friction and wear resistance (such as polytetrafluoroethylene or nylon materials) to reduce powder adhesion. The antistatic layer 932 prevents powder from adsorbing onto the surface of the composite membrane 93 due to static electricity (such as polyester fiber or conductive rubber materials), which is especially suitable for fine powders that are prone to static electricity (such as plastic particles and pharmaceutical powders) and avoids secondary bridging caused by static electricity. The skeleton layer 933 provides mechanical strength (such as glass fiber reinforced plastic or metal mesh) to ensure that the composite membrane 93 deforms stably under air pressure and avoids cracking or uncontrolled deformation due to insufficient strength. The airtight layer 934 ensures the chamber sealing (such as rubber or silicone materials) to prevent gas leakage during inflation / deflation and ensure the air pressure driving effect.

[0053] The permeation column 935 penetrates through each layer and protrudes from the contact layer 931. Its functions include: the permeation column 935 protrudes from the contact layer 931 to form a protrusion, which can be embedded in the powder layer to enhance the local disturbance effect (such as "piercing" the bridging structure); when the chamber is filled with gas, the high-pressure gas can permeate into the powder layer through the micropores of the permeation column 935 to form local microfluidization, which assists the mechanical expansion of the composite membrane 93 to break the arch.

[0054] Example 2: Please refer to Figure 4 and Figure 5 The difference between this embodiment and Embodiment 1 is that the support member is a fixed-point support assembly 95, which includes: an inner cylinder 954, one end of which is fixed to the pad 94, and the other end of which is slidably fitted with an outer cylinder 953, forming a buffer connection between the outer cylinder 953 and the inner cylinder 954; and a bracket 952, which is fixed to the outer cylinder 953, and the bracket 952 is provided with a plurality of support plates 951.

[0055] The inner cylinder 954 is fixed to the pad 94, and the outer cylinder 953 is slidably sleeved on the outside of the inner cylinder 954, forming a telescopic buffer structure. Multiple support discs 951 distribute the deformation pressure of the composite membrane 93 to a larger area, avoiding excessive local compression caused by single-point support.

[0056] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A bridging prevention device for a loss-in-weight feeder based on powder fluidization technology, characterized in that, include: The loss-in-weight feeder (3) includes a main bin and a hopper located below the main bin; Anti-bridging component (9) is embedded in the side wall of the loss-in-weight feeder (3); Multiple aerators (2) are distributed in the main chamber. The aerators (2) are supplied with air by air pipes (4) through air nozzles (1) on them, and the air pipes (4) are controlled by solenoid valves (5). An exhaust assembly (8) is disposed at the top of the main compartment; The solenoid valve (5) and the exhaust assembly (8) are both controlled by the controller (7), which can control the exhaust parameters of the exhaust assembly (8) to match the aeration parameters of the aerator (2). The exhaust assembly (8) includes: The exhaust pipe (81) is connected to the main compartment at the bottom and to the suction pipe (82) at the top. The suction pipe (82) is connected to a three-way valve, which is connected to a self-draining pipe and a suction pump respectively. A barrier net (83) is fixed in the exhaust pipe (81); The controller (7) can control the three-way valve to enable the exhaust pipe (81) to achieve adaptive exhaust by using the self-exhausting pipe, or to use the suction pump to exhaust in accordance with the aeration parameters of the aerator (2). The exhaust pipe (81) has a floating plate (85) slidably disposed inside, located below the barrier net (83), and a floating spring (86) is connected between the floating plate (85) and the exhaust pipe (81). The float plate (85) has multiple through holes, and an elastic conical hole (87) is embedded in the through hole. The elastic conical hole (87) gradually expands from bottom to top. The bottom of the barrier net (83) is fixed with an enlarged cylinder (84) corresponding to the elastic conical hole (87), and the side of the enlarged cylinder (84) has a side hole.

2. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 1, characterized in that, The aerator (2) is configured to aerate toward the anti-bridging assembly (9) so as to achieve passive arch breaking using the anti-bridging assembly (9).

3. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 1, characterized in that, The hopper is U-shaped or hemispherical, and two aerators (2) are symmetrically arranged in the hopper.

4. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 1, characterized in that, The side wall of the loss-in-weight feeder (3) is provided with stepped through holes; The anti-bridging component (9) includes: The base (91) is embedded into the stepped through hole, and a sealing ring gasket (92) and a sealing ring are provided between the base (91) and the stepped through hole. The base (91) has a groove at one end facing the inside of the loss-in-weight feeder (3). The composite membrane (93) is connected to the opening of the tank and together with the tank forms a chamber; A pad (94) is embedded in the groove, and a support is provided between the pad (94) and the composite membrane (93); An air supply head (97) is used to supply air to or extract air from the chamber.

5. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 4, characterized in that, The support component is a support spring (96).

6. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 4, characterized in that, The support is a fixed-point support assembly (95), which includes: The inner cylinder (954) is fixed at one end to the pad (94), and the outer cylinder (953) is slidably sleeved at the other end, forming a buffer connection between the outer cylinder (953) and the inner cylinder (954); A bracket (952) is fixed on the outer cylinder (953), and a plurality of support plates (951) are provided on the bracket (952).

7. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 4, characterized in that, The composite membrane (93) includes a contact layer (931), an antistatic layer (932), a skeleton layer (933), an airtight layer (934), and a permeation column (935) that are sequentially pasted from the side closest to the inside of the loss-in-weight feeder (3) outwards. The permeation column (935) protrudes from the contact layer (931) and forms a protrusion.

8. The anti-bridging device for a loss-in-weight feeder based on powder fluidization technology according to claim 4, characterized in that, The controller (7) is also configured to: when the anti-bridging assembly (9) is used to actively break the arch, control the air supply head (97) to first pulse-charge the chamber with air, then continuously apply pressure, and finally quickly evacuate the air.

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