Positive pressure air respirator is mainly composed of high pressure air cylinder and cylinder switch, pressure reducer, quick connector, positive pressure air supply valve, positive pressure full face mask, air source pressure gauge, cylinder residual gas alarm, medium pressure Safety valves, positive pressure exhalation valves, backrests, shoulder straps, belts and other components.
1. High-pressure cylinders and bottle valves (1) High-pressure cylinder materials High-pressure cylinder materials include high-strength steel, ultra-high-strength steel, carbon fiber, and Kevlar fibers.
(2) Structure of carbon fiber cylinders Carbon fiber composite cylinders are made of high-strength fibers such as aluminum alloy liners, external carbon fibers, glass fibers, and epoxy layers.
CFR178.463 aluminum alloy liner according to US Department of Transportation, AL manufacture manufacturing standards, 100% check items: thickness, straightness, concentricity, finish and hardness. The main winding layer is filament carbon fiber, and the outer layer is made of glass fiber and epoxy resin layers to increase impact resistance and wear resistance.
(3) Injury level: shallow depth to the resin layer;
Grade 2: Scratch to glass fiber, depth <0.25mm (white) repair resin.
Grade 3 (rejected): 1,> 0.25mm (dark grey);
2, strong acid and alkali corrosion places 3, scratches the horizontal projection length of the bottle for 3 / 4 weeks (4) cylinder valve through the hand wheel to open or close the high pressure gas cylinder valve.
EN-137 and GA-124 standards require that cylinder valve handwheels have a structure that prevents mis-closing. Cylinder valve outlet female G5/8 thread.
At present, various cylinder valves, according to different shapes, can be divided into three types: vertical, horizontal, and horizontal. The bottle valve is equipped with a safety diaphragm. When the pressure in the cylinder rises to 40-42 MPa, the pressure is automatically relieved, which can prevent the cylinder from burst due to the high pressure inside the bottle and avoid the casualties.
2, the integrated pressure reducer <br> <br> reducer assembly reducer assembly includes a pressure reducer, the pressure relief valve, the gas source residual gas alarms, pressure display means, the air outlet duct (pressure tube ), and so on, the role is to reduce the pressure of high-pressure gas to 0.7MPa, and continue to supply the right amount of air to meet the needs of human breathing. When the air pressure is between 3-30 MPa, the pressure in the pressure reducer chamber is 0.7±0.15 MPa. At this time, the maximum output flow is not less than 3001/min.
1 reducer pressure reducer generally brass or aluminum alloy as the material of the shell, its internal structure can be divided into two categories: piston and diaphragm type. Regardless of piston type or diaphragm type, it can be divided into two categories: constant pressure output and non-constant voltage output, so the pressure reducer can be divided into four types: constant pressure piston type, non-constant pressure type piston type, constant pressure diaphragm type Non-constant pressure diaphragm type.
The non-constant pressure piston is introduced to its structure and principle.
The regulator works as shown in the figure. The principle of the piston pressure reducer is to control the piston to move up and down by adjusting the spring pressure of the pressure and the pressure balance of the medium pressure chamber B to drive the valve rod to move, so that the gap between the valve rod and the valve seat is reduced or increased, and the control enters The air volume of the medium pressure chamber ensures that its output pressure is 0.7 MPa. When the wearer stops breathing, the pressure reducer gas output is zero,
As the gas pressure in the medium pressure chamber B rises, it will cause the piston 1 to move upwards, the high pressure gas will enter the middle pressure chamber, and the pressure in the middle pressure chamber will increase, pushing the piston to close the high pressure valve until the valve rod 10 and the valve 11 are between The gap is reduced and it is finally completely closed. When the wearer inhales, the pressure in the medium pressure chamber will decrease, and the pressure adjustment spring will push the piston and open the high pressure valve to achieve a new balance.
When the wearer inhales, the pressure in the medium pressure chamber will decrease, and the diaphragm bends inward under the elastic force of the main balance spring, which will push the top rod, open the high pressure valve, and the high pressure gas enters the middle pressure chamber. When the wearer stops inhaling, the pressure in the medium pressure chamber rises, pushing the diaphragm to reset and closing the high pressure valve to achieve a new balance.
The high-pressure valve head of the non-constant pressure output pressure reducer directly presses on the high pressure gas. With the change of the high pressure, the force on the valve head also changes, and therefore, the output pressure is not a constant pressure. Its structure is simple, and its maintenance is more convenient than the constant pressure output pressure reducer. Therefore, there are still some air respirator pressure reducers using non-constant pressure output pressure reducer.
The high pressure valve head of the constant pressure reducer is not topped on the high pressure gas, and its output pressure does not change with the change of the air source pressure, so that the gas supply valve maintains a constant pressure input, the suction resistance is relatively stable, and the wearer breathes for a long time , It is not easy to fatigue. It is a pressure reducer that is currently welcomed by wearers.
2 Medium pressure safety valve The role of the medium pressure safety valve is when the pressure reducer loses the decompression effect on the high pressure air (such as the decompression spring or the diaphragm, the valve is damaged), the medium pressure safety valve opens, and the high pressure air leaks through the safety valve. After the pressure is maintained, the pressure output is kept low to avoid direct output of high-pressure air and an accident occurs. It is required that the medium pressure safety valve should be opened when the pressure in the regulator chamber is (1±0.2) MPa.
Pressure relief valve works as shown in the figure. The elasticity of the medium pressure safety valve spring 4 has been adjusted according to technical requirements to ensure that when the pressure in the pressure reducer chamber is normal, the medium pressure safety valve is closed and the airtightness is ensured. When the pressure in the decompression chamber is out of control, the pressure is applied to the valve. The force is greater than the force exerted by the spring 4 on the valve. The valve is opened. The pressure in the decompression chamber enters into the medium pressure safety valve and is released through the small hole in the adjustment cap. When the pressure in the decompression chamber returns to normal, the valve closes and remains airtight.
3 gas source residual gas alarm gas source residual gas alarm function is when the cylinder pressure dropped to 5 ± 1MPa, issued an alarm sound to remind the wearer to quickly withdraw from the fire.
The gas pressure PA in the high pressure chamber A acts on the open top, causing the compression alarm adjustment spring to move to the right so that the open top contacts the valve pad and ensures airtightness. When the pressure of the gas in the high-pressure chamber A drops to a certain value, the force of the PA acting on the open top is less than the force of the alarm adjusting spring acting on the open top, and the open top moves to the left; the top is opened and the valve pad is disengaged, The high-pressure chamber gas emits an alarm sound by turning on the top inflow gas source residual gas alarm.
Since the alarm from the gas cylinder Ming completely used, air consumption to moderate labor intensity 30L / min calculations, the use of cylinders 5L, can continue to use 6 ~ lOmin. After hearing the alarm, the wearer should immediately evacuate the disaster area.
The nominal use time is calculated according to the following formula.
Cylinder volume (L)X cylinder working pressure (MPa)
Nominal use time =---------------------------------
30 (L/min) X0.098 (MPa)
In the formula:
30 (L/min) refers to the amount of air consumed by the relevant industries in China for each minute of moderate labor intensity.
The use time will be affected by many factors and different from the nominal use time. The gas consumption for different users and usage conditions is different. The higher the work intensity, the faster the gas consumption in the cylinder.
3, air pressure indicating means indicates air pressure <br> <br> apparatus by the high pressure conduits and pressure gauge for indicating gas pressure in the cylinder. Estimate the remaining working time. The high pressure conduit and pressure gauge housing are provided with a protective cover to prevent damage during impact.
4, and the intermediate pressure pipe quick connector <br> <br> pressure tube glial fabric hose, which with quick coupling consisting of soft air outlet duct connected at one end supply valve and the other end connected to the regulator.
Quick connector consists of two parts and the joint connector COMPOSITION, when the two members are not connected, connecting the pressure reducer flexible conduit connector housings are latched, open the cylinder does not leak even. When the quick connector of the air supply valve is inserted into the connector seat, the lock mechanism is opened to allow gas to enter the air supply valve.
The technical indicators of the alarm sound alarm have the following three requirements:
a) Starting sounding pressure b) Sound level and frequency range c) Consumption of gas consumed by the alarm The sound level of the alarm should be greater than or equal to 90 dB(A) within 1 m and the frequency should be maintained at 2000-4000 Hz. between.
5, supply valve assembly gas supply valve assembly (supply valve) is the pressure reducer output of the gas in accordance with the inspiratory volume of the wearer, decompressed again to the body can breathe the pressure for the wearer to breathe The device, which is a key component of a positive pressure air respirator, consists of a high-strength plastic housing, a rubber diaphragm, a rocker valve, and a positive pressure spring lever mechanism, and its output is connected to a full-face mask air inlet flexible catheter. With more than 2001/min gas supply capacity. The schematic diagram of the structure is shown in the figure.
The air supply valve assembly is mounted directly on the mask and a hose is connected to the medium pressure air line on the pressure reducer via a quick connector. The convex interface of the air supply valve is equipped with a ring gasket and is connected with the double-loop line of the air supply valve interface on the mask to form a double seal with reliable sealing.
The air interface of the air supply valve is provided with a row of air supply holes. When the air is used, the air is sprayed from the air supply hole to the inner surface of the window, and the accumulated mist or frost in the window can be quickly removed.
The rubber cover on the air supply valve protects the throttle switch. When the mask is removed from the face, press the middle part of the rubber cover with the thumb and press down completely, it will be accompanied by a "click" sound, you can close the air supply valve, stop the air supply, and avoid wasting the bottle of air. When the mask is again worn on the face to keep it sealed and inhaled, the air supply valve will automatically open and supply air.
The air supply valve assembly is mounted directly on the mask and a hose is connected to the medium pressure air line on the pressure reducer via a quick connector. The convex interface of the air supply valve is equipped with a ring gasket and is connected with the double-loop line of the air supply valve interface on the mask to form a double seal with reliable sealing.
The air interface of the air supply valve is provided with a row of air supply holes. When the air is used, the air is sprayed from the air supply hole to the inner surface of the window, and the accumulated mist or frost in the window can be quickly removed.
The rubber cover on the air supply valve protects the throttle switch. When the mask is removed from the face, press the middle part of the rubber cover with the thumb and press down completely, it will be accompanied by a "click" sound, you can close the air supply valve, stop the air supply, and avoid wasting the bottle of air. When the mask is again worn on the face to keep it sealed and inhaled, the air supply valve will automatically open and supply air.
The red knob on the air supply valve is the emergency flush valve and it has three functions:
1 When the supply valve accidentally fails, a manual rotation knob can be used to provide a constant air flow of at least 225L per minute by allowing the air to flow into the mask.
2 In addition to emergency air supply, it is also possible to use the outflow air to directly scour the face mask and dust and dirt inside the air supply valve to avoid inhalation.
3 It is also possible to vent the remaining air in the system line through the flush valve knob after closing the bottle valve.
The supply valve has two states, one is the working state and the other is the non-working state. The non-working state to the working state is achieved by inhaling or manually pressing the lever.
In the non-operating state of the positive-pressure air supply valve, the lever 11 and the diaphragm 10 are in a substantially parallel position but inclined slightly upward. The lever 11 drives the diaphragm 10 through the link 9 to disengage the rocker contact 12. Under the action of the spring 5, the rocker valve 6 and the input valve 4 are attached together.
During operation, the medium pressure air P1 enters the input port. Under the action of the pressure P1 and the spring 5, the valve 4 remains airtight. Under the action of the activation force, the diaphragm moves under the atmospheric pressure PH and moves toward the output port, and the lever 11 is driven by the linkage 9 to move in the same direction, so that the tension spring 2 generates pressure on the diaphragm 10 and accelerates the diaphragm to move downwards. The rocker head 12 is pressed to rock the rocker 8 to compress the spring 5 so that a gap is formed between the rocker valve and the valve seat, and the medium-pressure gas enters the diaphragm to generate the air pressure P2. The diaphragm is in equilibrium under atmospheric pressure, spring 2 tension, contact 12 thrust and output pressure P2, maintaining a certain gap, at which time the output flow equals the input flow.
When the output flow increases or decreases, the air pressure P2 under the diaphragm will decrease or increase, the diaphragm will move downwards or upwards, the rocker valve clearance will become larger or smaller, and the air flow entering the supply valve will be automatically adjusted. To equalize the output and input traffic.
When the output flow is zero (ie, exhalation or breath-hold state), the diaphragm pressure rises, the diaphragm moves up, the rocker valve closes, the air no longer enters under the diaphragm, and the diaphragm is in the zero output equilibrium position.
From the above analysis, it can be known that the diaphragm is balanced under atmospheric pressure, spring 2 pull force, output pressure P2, and thrust force. As long as the appropriate tension spring 2 is selected, the air pressure P2 under the diaphragm can always be greater than the atmospheric pressure.
6, mask assembly
The mask assembly (mask) is a device that covers the face and isolates toxic and harmful gases from entering the body's respiratory system (see figure). In order to ensure an effective seal with the human face, the mask assembly has three sizes: small, large, and extra large. it includes:
1 side window: monocular, curved surface, made of high strength polycarbonate injection molding, impact resistance, the surface is coated with a wear layer, good light transmittance, no distortion. In use, air is sprayed onto the inner surface of the window through a row of holes in the air supply valve, flushing the fog generated by the window due to the temperature difference.
2 mouth and nose mask: installed in the lower part of the mask, with the person's mouth and nose are in good agreement, can reduce the air consumption and the actual harmful space, improve the utilization of air, but also reduce the suction resistance.
3 Microphone: There is a microphone assembly on both sides of the window, which can provide double sound transmission to the wearer and can be connected with sound amplifiers and wired and wireless communication systems.
4 face frame seals: Located around the mask to ensure good fit with the human face and forehead. It is made of special rubber material, texture is flexible, reliable sealing, comfortable to wear and will not cause skin allergies.
5 Hood assembly: head cover assembly using Kevlar thin mesh structure, adjustable by two head straps and two neck straps and mask connection, so that the face and mask to maintain a good seal, even force, no Local pressure feeling.
The concave interface at the front of the window can be quickly connected with the convex interface of the air supply valve and forms a reliable seal.
7, the back bracket assembly <br> <br> back frame assembly includes a back frame, strap, belt and band fixed cylinder bottles. The back support is used to install the cylinder assembly and pressure reducer assembly.
Backrest is made of fire-retardant material and the shape is suitable for the curve characteristics of the human body back. The wide belt and shoulder strap make it comfortable to wear and reduce the wearer's fatigue.
The shoulder straps and belts are woven from flame-retardant materials and are equipped with a quick tightening self-locking and relaxing device.
1. High-pressure cylinders and bottle valves (1) High-pressure cylinder materials High-pressure cylinder materials include high-strength steel, ultra-high-strength steel, carbon fiber, and Kevlar fibers.
(2) Structure of carbon fiber cylinders Carbon fiber composite cylinders are made of high-strength fibers such as aluminum alloy liners, external carbon fibers, glass fibers, and epoxy layers.
CFR178.463 aluminum alloy liner according to US Department of Transportation, AL manufacture manufacturing standards, 100% check items: thickness, straightness, concentricity, finish and hardness. The main winding layer is filament carbon fiber, and the outer layer is made of glass fiber and epoxy resin layers to increase impact resistance and wear resistance.
(3) Injury level: shallow depth to the resin layer;
Grade 2: Scratch to glass fiber, depth <0.25mm (white) repair resin.
Grade 3 (rejected): 1,> 0.25mm (dark grey);
2, strong acid and alkali corrosion places 3, scratches the horizontal projection length of the bottle for 3 / 4 weeks (4) cylinder valve through the hand wheel to open or close the high pressure gas cylinder valve.
EN-137 and GA-124 standards require that cylinder valve handwheels have a structure that prevents mis-closing. Cylinder valve outlet female G5/8 thread.
At present, various cylinder valves, according to different shapes, can be divided into three types: vertical, horizontal, and horizontal. The bottle valve is equipped with a safety diaphragm. When the pressure in the cylinder rises to 40-42 MPa, the pressure is automatically relieved, which can prevent the cylinder from burst due to the high pressure inside the bottle and avoid the casualties.
2, the integrated pressure reducer <br> <br> reducer assembly reducer assembly includes a pressure reducer, the pressure relief valve, the gas source residual gas alarms, pressure display means, the air outlet duct (pressure tube ), and so on, the role is to reduce the pressure of high-pressure gas to 0.7MPa, and continue to supply the right amount of air to meet the needs of human breathing. When the air pressure is between 3-30 MPa, the pressure in the pressure reducer chamber is 0.7±0.15 MPa. At this time, the maximum output flow is not less than 3001/min.
1 reducer pressure reducer generally brass or aluminum alloy as the material of the shell, its internal structure can be divided into two categories: piston and diaphragm type. Regardless of piston type or diaphragm type, it can be divided into two categories: constant pressure output and non-constant voltage output, so the pressure reducer can be divided into four types: constant pressure piston type, non-constant pressure type piston type, constant pressure diaphragm type Non-constant pressure diaphragm type.
The non-constant pressure piston is introduced to its structure and principle.
The regulator works as shown in the figure. The principle of the piston pressure reducer is to control the piston to move up and down by adjusting the spring pressure of the pressure and the pressure balance of the medium pressure chamber B to drive the valve rod to move, so that the gap between the valve rod and the valve seat is reduced or increased, and the control enters The air volume of the medium pressure chamber ensures that its output pressure is 0.7 MPa. When the wearer stops breathing, the pressure reducer gas output is zero,
As the gas pressure in the medium pressure chamber B rises, it will cause the piston 1 to move upwards, the high pressure gas will enter the middle pressure chamber, and the pressure in the middle pressure chamber will increase, pushing the piston to close the high pressure valve until the valve rod 10 and the valve 11 are between The gap is reduced and it is finally completely closed. When the wearer inhales, the pressure in the medium pressure chamber will decrease, and the pressure adjustment spring will push the piston and open the high pressure valve to achieve a new balance.
When the wearer inhales, the pressure in the medium pressure chamber will decrease, and the diaphragm bends inward under the elastic force of the main balance spring, which will push the top rod, open the high pressure valve, and the high pressure gas enters the middle pressure chamber. When the wearer stops inhaling, the pressure in the medium pressure chamber rises, pushing the diaphragm to reset and closing the high pressure valve to achieve a new balance.
The high-pressure valve head of the non-constant pressure output pressure reducer directly presses on the high pressure gas. With the change of the high pressure, the force on the valve head also changes, and therefore, the output pressure is not a constant pressure. Its structure is simple, and its maintenance is more convenient than the constant pressure output pressure reducer. Therefore, there are still some air respirator pressure reducers using non-constant pressure output pressure reducer.
The high pressure valve head of the constant pressure reducer is not topped on the high pressure gas, and its output pressure does not change with the change of the air source pressure, so that the gas supply valve maintains a constant pressure input, the suction resistance is relatively stable, and the wearer breathes for a long time , It is not easy to fatigue. It is a pressure reducer that is currently welcomed by wearers.
2 Medium pressure safety valve The role of the medium pressure safety valve is when the pressure reducer loses the decompression effect on the high pressure air (such as the decompression spring or the diaphragm, the valve is damaged), the medium pressure safety valve opens, and the high pressure air leaks through the safety valve. After the pressure is maintained, the pressure output is kept low to avoid direct output of high-pressure air and an accident occurs. It is required that the medium pressure safety valve should be opened when the pressure in the regulator chamber is (1±0.2) MPa.
Pressure relief valve works as shown in the figure. The elasticity of the medium pressure safety valve spring 4 has been adjusted according to technical requirements to ensure that when the pressure in the pressure reducer chamber is normal, the medium pressure safety valve is closed and the airtightness is ensured. When the pressure in the decompression chamber is out of control, the pressure is applied to the valve. The force is greater than the force exerted by the spring 4 on the valve. The valve is opened. The pressure in the decompression chamber enters into the medium pressure safety valve and is released through the small hole in the adjustment cap. When the pressure in the decompression chamber returns to normal, the valve closes and remains airtight.
3 gas source residual gas alarm gas source residual gas alarm function is when the cylinder pressure dropped to 5 ± 1MPa, issued an alarm sound to remind the wearer to quickly withdraw from the fire.
The gas pressure PA in the high pressure chamber A acts on the open top, causing the compression alarm adjustment spring to move to the right so that the open top contacts the valve pad and ensures airtightness. When the pressure of the gas in the high-pressure chamber A drops to a certain value, the force of the PA acting on the open top is less than the force of the alarm adjusting spring acting on the open top, and the open top moves to the left; the top is opened and the valve pad is disengaged, The high-pressure chamber gas emits an alarm sound by turning on the top inflow gas source residual gas alarm.
Since the alarm from the gas cylinder Ming completely used, air consumption to moderate labor intensity 30L / min calculations, the use of cylinders 5L, can continue to use 6 ~ lOmin. After hearing the alarm, the wearer should immediately evacuate the disaster area.
The nominal use time is calculated according to the following formula.
Cylinder volume (L)X cylinder working pressure (MPa)
Nominal use time =---------------------------------
30 (L/min) X0.098 (MPa)
In the formula:
30 (L/min) refers to the amount of air consumed by the relevant industries in China for each minute of moderate labor intensity.
The use time will be affected by many factors and different from the nominal use time. The gas consumption for different users and usage conditions is different. The higher the work intensity, the faster the gas consumption in the cylinder.
3, air pressure indicating means indicates air pressure <br> <br> apparatus by the high pressure conduits and pressure gauge for indicating gas pressure in the cylinder. Estimate the remaining working time. The high pressure conduit and pressure gauge housing are provided with a protective cover to prevent damage during impact.
4, and the intermediate pressure pipe quick connector <br> <br> pressure tube glial fabric hose, which with quick coupling consisting of soft air outlet duct connected at one end supply valve and the other end connected to the regulator.
Quick connector consists of two parts and the joint connector COMPOSITION, when the two members are not connected, connecting the pressure reducer flexible conduit connector housings are latched, open the cylinder does not leak even. When the quick connector of the air supply valve is inserted into the connector seat, the lock mechanism is opened to allow gas to enter the air supply valve.
The technical indicators of the alarm sound alarm have the following three requirements:
a) Starting sounding pressure b) Sound level and frequency range c) Consumption of gas consumed by the alarm The sound level of the alarm should be greater than or equal to 90 dB(A) within 1 m and the frequency should be maintained at 2000-4000 Hz. between.
5, supply valve assembly gas supply valve assembly (supply valve) is the pressure reducer output of the gas in accordance with the inspiratory volume of the wearer, decompressed again to the body can breathe the pressure for the wearer to breathe The device, which is a key component of a positive pressure air respirator, consists of a high-strength plastic housing, a rubber diaphragm, a rocker valve, and a positive pressure spring lever mechanism, and its output is connected to a full-face mask air inlet flexible catheter. With more than 2001/min gas supply capacity. The schematic diagram of the structure is shown in the figure.
The air supply valve assembly is mounted directly on the mask and a hose is connected to the medium pressure air line on the pressure reducer via a quick connector. The convex interface of the air supply valve is equipped with a ring gasket and is connected with the double-loop line of the air supply valve interface on the mask to form a double seal with reliable sealing.
The air interface of the air supply valve is provided with a row of air supply holes. When the air is used, the air is sprayed from the air supply hole to the inner surface of the window, and the accumulated mist or frost in the window can be quickly removed.
The rubber cover on the air supply valve protects the throttle switch. When the mask is removed from the face, press the middle part of the rubber cover with the thumb and press down completely, it will be accompanied by a "click" sound, you can close the air supply valve, stop the air supply, and avoid wasting the bottle of air. When the mask is again worn on the face to keep it sealed and inhaled, the air supply valve will automatically open and supply air.
The air supply valve assembly is mounted directly on the mask and a hose is connected to the medium pressure air line on the pressure reducer via a quick connector. The convex interface of the air supply valve is equipped with a ring gasket and is connected with the double-loop line of the air supply valve interface on the mask to form a double seal with reliable sealing.
The air interface of the air supply valve is provided with a row of air supply holes. When the air is used, the air is sprayed from the air supply hole to the inner surface of the window, and the accumulated mist or frost in the window can be quickly removed.
The rubber cover on the air supply valve protects the throttle switch. When the mask is removed from the face, press the middle part of the rubber cover with the thumb and press down completely, it will be accompanied by a "click" sound, you can close the air supply valve, stop the air supply, and avoid wasting the bottle of air. When the mask is again worn on the face to keep it sealed and inhaled, the air supply valve will automatically open and supply air.
The red knob on the air supply valve is the emergency flush valve and it has three functions:
1 When the supply valve accidentally fails, a manual rotation knob can be used to provide a constant air flow of at least 225L per minute by allowing the air to flow into the mask.
2 In addition to emergency air supply, it is also possible to use the outflow air to directly scour the face mask and dust and dirt inside the air supply valve to avoid inhalation.
3 It is also possible to vent the remaining air in the system line through the flush valve knob after closing the bottle valve.
The supply valve has two states, one is the working state and the other is the non-working state. The non-working state to the working state is achieved by inhaling or manually pressing the lever.
In the non-operating state of the positive-pressure air supply valve, the lever 11 and the diaphragm 10 are in a substantially parallel position but inclined slightly upward. The lever 11 drives the diaphragm 10 through the link 9 to disengage the rocker contact 12. Under the action of the spring 5, the rocker valve 6 and the input valve 4 are attached together.
During operation, the medium pressure air P1 enters the input port. Under the action of the pressure P1 and the spring 5, the valve 4 remains airtight. Under the action of the activation force, the diaphragm moves under the atmospheric pressure PH and moves toward the output port, and the lever 11 is driven by the linkage 9 to move in the same direction, so that the tension spring 2 generates pressure on the diaphragm 10 and accelerates the diaphragm to move downwards. The rocker head 12 is pressed to rock the rocker 8 to compress the spring 5 so that a gap is formed between the rocker valve and the valve seat, and the medium-pressure gas enters the diaphragm to generate the air pressure P2. The diaphragm is in equilibrium under atmospheric pressure, spring 2 tension, contact 12 thrust and output pressure P2, maintaining a certain gap, at which time the output flow equals the input flow.
When the output flow increases or decreases, the air pressure P2 under the diaphragm will decrease or increase, the diaphragm will move downwards or upwards, the rocker valve clearance will become larger or smaller, and the air flow entering the supply valve will be automatically adjusted. To equalize the output and input traffic.
When the output flow is zero (ie, exhalation or breath-hold state), the diaphragm pressure rises, the diaphragm moves up, the rocker valve closes, the air no longer enters under the diaphragm, and the diaphragm is in the zero output equilibrium position.
From the above analysis, it can be known that the diaphragm is balanced under atmospheric pressure, spring 2 pull force, output pressure P2, and thrust force. As long as the appropriate tension spring 2 is selected, the air pressure P2 under the diaphragm can always be greater than the atmospheric pressure.
6, mask assembly
The mask assembly (mask) is a device that covers the face and isolates toxic and harmful gases from entering the body's respiratory system (see figure). In order to ensure an effective seal with the human face, the mask assembly has three sizes: small, large, and extra large. it includes:
1 side window: monocular, curved surface, made of high strength polycarbonate injection molding, impact resistance, the surface is coated with a wear layer, good light transmittance, no distortion. In use, air is sprayed onto the inner surface of the window through a row of holes in the air supply valve, flushing the fog generated by the window due to the temperature difference.
2 mouth and nose mask: installed in the lower part of the mask, with the person's mouth and nose are in good agreement, can reduce the air consumption and the actual harmful space, improve the utilization of air, but also reduce the suction resistance.
3 Microphone: There is a microphone assembly on both sides of the window, which can provide double sound transmission to the wearer and can be connected with sound amplifiers and wired and wireless communication systems.
4 face frame seals: Located around the mask to ensure good fit with the human face and forehead. It is made of special rubber material, texture is flexible, reliable sealing, comfortable to wear and will not cause skin allergies.
5 Hood assembly: head cover assembly using Kevlar thin mesh structure, adjustable by two head straps and two neck straps and mask connection, so that the face and mask to maintain a good seal, even force, no Local pressure feeling.
The concave interface at the front of the window can be quickly connected with the convex interface of the air supply valve and forms a reliable seal.
7, the back bracket assembly <br> <br> back frame assembly includes a back frame, strap, belt and band fixed cylinder bottles. The back support is used to install the cylinder assembly and pressure reducer assembly.
Backrest is made of fire-retardant material and the shape is suitable for the curve characteristics of the human body back. The wide belt and shoulder strap make it comfortable to wear and reduce the wearer's fatigue.
The shoulder straps and belts are woven from flame-retardant materials and are equipped with a quick tightening self-locking and relaxing device.
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