CN201954697U - Overflow-preventive humidifier capable of preventing water leakage during lifting of water tank - Google Patents

Abstract

The utility model discloses a water leakage and overflow prevention humidifier with a waterproof box, which comprises a base, a water tank, and a water mist distribution pipe. The base is provided with an ultrasonic water mist generating mechanism, an air supply mechanism and a control mechanism. The water tank The bottom is provided with an inlet and outlet pipe for water to enter and exit the water tank, and a water stopper with a sealing plug to prevent the tank from overflowing is provided on the inlet and outlet pipe, and an opening lever is provided in the ultrasonic water mist generating mechanism; installed on the water tank When it is on the base, the opening rod is inserted into the water stopper and the sealing plug moves up to open the inlet and outlet pipes; when the water tank is lifted off the base, the sealing plug moves down to block the inlet and outlet pipes. The utility model provides a water-leakage and overflow-proof humidifier with simple structure, reliable control and high safety.

Description

Waterproof Case Lift Leaky & Anti-Flood Humidifier

technical field

The utility model relates to a humidifier, in particular to a water-leakage and overflow-proof humidifier with a waterproof box.

Background technique

Relevant studies have shown that in the past 30 years, with the increase of global temperature year by year, the air humidity has been decreasing year by year. The incidence of diseases such as influenza, bronchial asthma, allergic dermatitis, and emphysema has increased by more than 30% compared with 30 years ago; People in a sub-healthy state have weaker body resistance than healthy people and are vulnerable to viruses and bacteria, and low humidity environments are conducive to germs The reproduction and spread of germs are even more rampant. But when the air humidity reaches 55%, it is difficult for germs to spread, so the air humidity that is beneficial to human health should be kept between 45% and 55%. However, there are few families in modern cities that meet this standard. In response to the above situation, people have designed equipment that can improve air humidity. This equipment is a humidifier. The existing humidifiers include ultrasonic type, direct evaporation type, electric heating type, centrifugal type, compound type, etc., and the most commonly used one is the ultrasonic type humidifier. The working principle of the ultrasonic type is to use the principle of 1.7M ultrasonic high-frequency oscillation to atomize water into ultrafine particles of 1-5 microns, and diffuse the water mist into the air through the pneumatic device to achieve the purpose of evenly humidifying the air.

The main components of the ultrasonic humidifier include a water tank, an ultrasonic water mist generating mechanism, an air supply mechanism for increasing the diffusion speed of the water mist, and a water mist distribution pipe that gathers the water mist generated by the ultrasonic water mist generating mechanism and distributes it into the air. In the existing humidifier, the water tank is arranged above the ultrasonic water mist generating mechanism, and the bottom surface of the water tank is provided with a water inlet and outlet pipe for adding water to the water tank, and the water in the water tank flows out from the water tank through the water inlet and outlet under the action of gravity Ultrasonic nebulization into the sink. Since the inlet and outlet pipes are located at the bottom of the water tank, when the water tank is lifted to add water or to repair the water tank, the water in the water tank will leak from the water inlet and outlet when the water tank is lifted, and the water that leaks into the water tank will splash around if it exceeds the capacity of the water tank Sprinkle, affect the normal use of users. In addition, since the water inlet and outlet pipes are arranged on the bottom of the water tank, after the water inlet and outlet pipes are opened, water will leak into the tank continuously, and the water tank will overflow when it is full. An overflow device needs to be installed to prevent the tank from overflowing.

Utility model content

The technical problem to be solved by the utility model is that, aiming at the defects of the water tank leaking when the water tank is lifted to add water in the prior art, it provides a simple structure, reliable control, high safety, and the inlet and outlet pipes are sealed and overflow-proof after the water tank is lifted. The waterproof case lifts the leak-proof and overflow-proof humidifier.

The technical solution adopted by the utility model to solve the technical problem is: a water-proof box lifts a water leakage and overflow-proof humidifier, including a base, a water tank, and a water mist distribution pipe. The base is equipped with an ultrasonic water mist generating mechanism, an Wind mechanism and control mechanism, the bottom of the water tank is provided with an inlet and outlet pipe for water to enter and exit the water tank, the water inlet and outlet is provided with a water stopper with a sealing plug to prevent overflow, and the ultrasonic water mist generating mechanism is equipped with There is an opening lever; when the water tank is installed on the base, the opening lever is inserted into the water stopper to push the sealing plug upward to open the inlet and outlet pipes; when the water tank is lifted off the base, the sealing plug moves down to block the inlet and outlet pipes.

The ultrasonic water mist generating mechanism includes a water tank arranged above the base, the opening rod is arranged in the water tank, and corresponds to the water stopper up and down; the water stopper is screwed to the water inlet and outlet of the water tank.

The water stopper includes a water stopper shell and a water stopper rod screwed on the inlet and outlet pipes, the water stopper case has a water outlet, and the sealing plug is arranged on the water stopper rod; The water rod is covered with a pre-tightened return spring, and the sealing plug is inserted in the water outlet and seals the water outlet under the action of the return spring.

A guide mechanism is arranged in the housing of the water shutoff device, and the water shutoff rod is inserted into the guide mechanism and moves up and down along the guide mechanism to seal the water outlet or open the water outlet.

The guide mechanism includes a support rod, one end of the support rod is fixed on the water stopper shell, the other end of the support rod or the support rod is provided with a guide ring, and the guide ring corresponds to the water outlet on the water stopper shell up and down , the water blocking rod is inserted in the guide ring, and moves up and down under the limit of the guide ring.

The shell of the water stopper is cylindrical, and the end surface of the top end is provided with a screw connection groove which is screwed with the water inlet and outlet of the water tank. The screw connection groove includes the side wall surface of the inner ring and the side wall surface of the outer ring. The external thread provided at the water inlet and outlet port is screwed together with the internal thread on the side wall surface of the outer ring in the threaded groove.

The groove bottom of the screw connection groove is opened with a limit groove, and a sealing ring is placed in the screw connection groove, and a protrusion is provided on the seal ring, and the protrusion is clamped in the limit groove to limit the sealing ring. radial movement.

The bottom of the water tank is provided with an ultrasonic oscillator, and above the ultrasonic oscillator is provided with a leak-proof cover for sealing the space of the water tank above the ultrasonic oscillator. The periphery of the leak-proof cover is inserted into the water tank and submerged into the water surface. The seal is connected to the leak-proof cover and communicates with the inner space of the leak-proof cover.

The outer wall of the lower part of the leak-proof cover is attached to the inner wall of the water tank.

The outer diameter of the upper part of the leak-proof cover is larger than the outer diameter of the lower part, and the upper part and the lower part of the leak-proof cover transition through steps, and when the leak-proof cover is inserted into the water tank, the steps press against the upper surface of the water tank.

The utility model is provided with a water stopper on the inlet and outlet water pipes at the bottom of the water tank. The water stopper is provided with a sealing plug for sealing the inlet and outlet water pipes. The corresponding ultrasonic water mist generating mechanism is provided with an opening lever; the water tank is installed on the base When it is up, the opening rod is inserted into the water stopper and the sealing plug moves up to open the inlet and outlet pipes; when the water tank is lifted away from the base, the sealing plug moves down to block the inlet and outlet pipes. This solves the problem of water tank lifting leakage. In addition, the water stopper is a downward extension of the water inlet and outlet pipes. When the water in the water tank continues to flow out, the water in the sink that receives the water from the water tank gradually rises and submerges the lower end of the water stopper, and the water tank is closed. When the cavity in the water tank Gradually form a negative pressure. When the gravity of the water is equal to the external atmospheric pressure, a balance is formed, and the water in the water tank will not enter the water tank again, which solves the problem of overflow caused by the continuous leakage of the water tank. The utility model has the advantages of simple structure, reliable control, easy operation and high safety.

The utility model adopts the anti-failure structure of the sealing ring in the leak-proof water blocking device to solve the problem that when the conventional annular plane sealing ring is tightened, the sealing ring will be deformed due to external force extrusion, and the water inlet and outlet of the water tank will be out of contact with each other. There is a problem of misalignment and seal failure. In the utility model, a limit groove is provided in the screw connection groove of the water stopper, and a protrusion is arranged on the corresponding sealing ring, and the protrusion is placed in the limit groove. When the water stopper is tightened, the protrusion is limited by the limit groove. The position ensures that the sealing ring does not deviate, so that the sealing ring can effectively play a sealing effect and ensure the safety of the product.

Description of drawings

The utility model will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is the sectional view of the utility model embodiment;

Fig. 2 is the sectional view of another direction of the utility model embodiment;

Fig. 3 is a partially enlarged view of the connection between the water stopper and the water tank of the embodiment of the present invention;

Fig. 4 is a partially enlarged view of the water stopper according to the embodiment of the present invention when it is pressed and opened by the opening rod;

Fig. 5 is a partially enlarged view of the screw connection between the water stopper and the water tank in the embodiment of the present invention.

Detailed ways

Embodiment 1, as shown in Figures 1 and 2, a water-proof box lifts a leaking and overflow-proof humidifier, including a base 4 and a water tank 1 arranged above the base 4, and the upper part of the base 4 is provided with ultrasonic water mist generation Mechanism 3, the lower part is provided with the blower mechanism 6 that is used to increase the speed of water mist diffusion and the control mechanism (not shown in the figure) that is used to control the work of humidifier, and the top of base 4 is also provided with water mist distribution pipe 2. Wherein the effect of base 4 is to be used for supporting water tank 1 and as the shell that encloses ultrasonic water mist generating mechanism 3, blower mechanism 6 and control mechanism. As shown in Figures 1, 2, and 4, the bottom of the water tank 1 is provided with an inlet and outlet pipe mouth 11 for water to enter and exit the water tank 1, and the water inlet and outlet pipe mouth 11 is provided with a water stopper 8 with a sealing plug 81. The ultrasonic water mist generating mechanism 3 is provided with an opening lever 33; when the water tank 1 is installed on the base 4, the opening lever 33 is inserted into the water stopper 8 and presses the sealing plug 81 to move upward to open the water inlet and outlet pipe port 11; lift the water tank 1 to leave the base At 4 o'clock, the sealing plug 81 moves down to block the inlet and outlet water pipe mouth 11.

As shown in Figures 1 and 4, the ultrasonic water mist generating mechanism 3 includes a water tank 31 arranged above the base 4, the opening lever 33 is arranged in the water tank 31, and corresponds to the water stopper 8 up and down; Device 8 is screwed on the water inlet and outlet pipe mouth 11 of water tank 1.

As shown in Figures 1, 2, 3, and 4, a leak-proof cover 5 is provided on the bottom surface of the water tank, and the leak-proof cover 5 has a connection hole, and the water inlet and outlet pipe mouth 11 of the water tank 1 is inserted in the connection hole, so The leakage-proof cover 5 is sealed and connected with the inlet and outlet water pipe mouth 11 of the water tank 1 . The water inlet and outlet pipe mouth 11 of the water tank 1 is vertically arranged on the bottom surface of the water tank 1, the water stopper 8 is screwed on the water inlet and outlet pipe mouth 11 of the water tank 1, and the water stopper opening rod 33 is also vertically arranged in the water tank 31. The water device 8 includes a water stopper housing 80, a water stopper rod 82 with a sealing plug 81 at one end, the water stopper housing 80 is cylindrical, and the water stopper housing 80 is screwed with the inlet and outlet water pipe mouth 11 of the water tank 1. connected, and a water outlet 86 is opened on the water blocking device housing 80, and a pre-tightened restoring spring 83 is set on the water blocking rod 82, and one end of the restoring spring 83 presses the water blocking device housing 80, and the other end presses The stopper 85 provided at the end of the water plugging rod 82 , the restoring spring 83 stretches elastically to seal and press the sealing plug 81 inserted into the water outlet 86 against the edge of the water outlet 86 . The water tank 1 is assembled on the base 4, and the opening rod 33 of the water stopper presses the end of the water stopper rod 82 of the water stopper 8 upwards, so that the water stopper rod 82 moves upwards, away from the edge of the water outlet 86, and the water tank 1 The water in the water leaks into the water tank 31 from the water outlet 86 . When the water tank 1 is lifted up, the opening rod 33 of the water stopper leaves the water stopper rod 82, then under the elastic force of the recovery spring 83, the water stopper rod 82 moves down to block the water outlet 86, and the water in the water tank 1 no longer leaks to the water tank 31 .

As shown in FIGS. 1 , 2 , 4 and 5 , a guide mechanism 88 is provided inside the water shutoff device housing 80 , and the water shutoff rod 82 is inserted in the guide mechanism 88 and moves up and down along the guide mechanism 88 . The guide mechanism 88 is used to guide the water blocking rod 82, so it may or may not be provided. The guide mechanism 88 enables the water blocking rod 82 to move vertically up and down, so as to prevent the sealing plug 81 from deviating and unable to compress the water outlet 86 . The guide mechanism 88 can have a variety of ways: one is a guide cylinder in which the water blocking rod 82 can be inserted, the second is a guide rod with a guide groove, and the water blocking rod 82 slides and fits up and down in the guide groove of the guide rod Sliding, the third is to set the limit rods, two limit rods are arranged on the outside of the water blocking rod 82, and the water blocking rod 82 can only move up and down by the limit. The guide mechanism 88 of the utility model is at least one support rod 881 fixed on the water stopper housing 80, one end of the support rod 881 is fixed on the water stopper housing 80, and the other end of the support rod 881 is provided with a guide ring 882, The guide ring 882 corresponds up and down to the water outlet 86 on the water stopper housing 80 , and the water stopper rod 82 is inserted in the guide ring 882 and moves up and down under the limit of the guide ring 882 .

As shown in Fig. 5, the water stopper housing 80 is a cylindrical shape that penetrates up and down, and there is a screw groove 84 on the end surface of the top end that is screwed with the inlet and outlet of the water tank. The screw groove 84 Including the inner ring side wall surface 841 and the outer ring side wall surface 842, the inner ring side wall surface 841 and the outer ring side wall surface 842 are generally arranged concentrically. The external thread provided on the water inlet and outlet pipe port 11 cooperates and is screwed with the internal thread on the outer ring side wall surface 842 in the threaded groove 84 . The bottom of the screw groove 84 is provided with a limiting groove 843, and a sealing ring 87 is placed in the screw groove 84. The sealing ring 87 is provided with a protrusion 871, and the protrusion 871 is placed in a position limiting position. The radial movement of the sealing ring is limited in the groove 843, the shape of the limiting groove 843 and the protrusion 871 are matched, and the two are fit without clearance or tight fit, and the limiting groove 843 is at any position of the groove bottom of the screwed groove 84, preferably The limit groove 843 is provided one circle close to the side wall surface 841 of the inner ring, and the protrusion 871 is also provided one circle correspondingly. In this embodiment, the cross section of the limiting groove 843 is rectangular, and the cross section of the protrusion 871 is also rectangular. The positioning of the sealing ring 87 by the limiting groove 843 is strengthened to prevent misalignment between it and the water inlet and outlet pipe port 11 of the water tank 1 due to extrusion and deformation by external force, and the problem of sealing failure.

The ultrasonic water mist generating mechanism 3 includes a water tank 31 arranged on the top of the base 4. The water tank 31 can be a tank body that is independently arranged and set on the top of the base 4, or can directly use the water tank 31 formed by the base 4, that is, the upper part of the base 4 is provided There is a transverse dividing plate, and the dividing plate and the base 4 have an integrated structure, and the space of the base 4 above the dividing plate forms a water tank 31 . An ultrasonic oscillator 32 is provided at the bottom of the water tank 31 . The ultrasonic vibrator 32 includes an oscillating plate 321 sealed and fixed in the fixing hole provided at the bottom of the water tank 31. The oscillating plate is arranged obliquely, with an inclination angle of about 7°. An oscillation control device 322 and an adjustment device 323 are arranged below the oscillating plate 321 to control the oscillation. The device 322 and the adjusting device 323 are prior art, and will not be described in detail here.

The top of the ultrasonic oscillator 32 is provided with a leak-proof cover 5 for sealing the space of the water tank 31 above the ultrasonic oscillator 32. The periphery of the leak-proof cover 5 is inserted into the water tank 31 and its edge is submerged in the water, preferably lower than the water tank 31. The preset working water level line of the humidifier is to ensure that the oscillating plate 321 in the ultrasonic humidifier can work normally when there is water. It is precisely because there is always water in the water tank 31 that this The utility model utilizes the principle of water sealing to seal the periphery of the leak-proof cover 5 arranged in the water tank 31 in the water.

As shown in Figures 1 and 2, the leak-proof cover 5 can be set independently, and the leak-proof cover 5 can also be fixed on the bottom of the water tank 1. When the water tank 1 is lifted, the leak-proof cover 5 is taken off, and the water tank 31 can be easily cleaned. Since the function of the leakproof cover 5 is to seal and guide the water mist, its shape is not limited, and it can be any shape that is upside down in the water tank 31 . In this embodiment, the leak-proof cover 5 is preferably in the shape of an inverted barrel, its top surface matches the shape of the bottom of the water tank, its side walls are perpendicular to the top surface, and the bottom of the water tank 1 is fitted and fixedly connected with the leak-proof cover 5 . The leak-proof cover 5 can seal the water tank 31 as a whole, or only seal the space around the oscillating plate 321 . In order to prevent all water mist from leaking from the edge of the water tank 31 as much as possible, it is preferable that the outer wall surface of the lower part of the leakproof cover 5 is attached to the inner wall surface of the water tank 31 . That is, the leak-proof cover 5 is inserted into the water against the inner wall of the water tank 31, and the gap between the leak-proof cover 5 and the water tank 31 is small to reduce water mist leakage.

The water tank 1 is a container for storing water, which needs to be removed and filled with water, so it is more likely to be bumped and dropped. The water tank 1 in the prior art is ultrasonically welded together by multiple parts of AS material and ABS material. It is easy to crack at the ultrasonic bonding line. In order to avoid this problem, the utility model adopts an integrally formed structure with a hollow cavity. And the water tank 1 can be made of a material with high toughness and strength, such as PC blown plastic, and the water tank 1 is formed at one time by using plastic manufacturing processes such as blow molding, so that the water tank 1 is a whole, so water leakage is greatly reduced question. The bottom of the water tank 1 is provided with a water inlet and outlet port 11, and the hollow cavity of the water tank 1 communicates with the outside world only through the water inlet and outlet port 11.

The air supply mechanism 6 of the water mist diffusion speed is arranged on the lower part of the base 4, the air supply mechanism 6 is mainly a fan, and the fan is connected with an air supply channel 61, and the air outlet of the air supply channel 61 is arranged in the leakproof cover 5, It is higher than the preset humidifier working water level in the water tank 31, so that the water in the water tank 31 will not enter the fan and damage the fan. In order to reduce the noise of the humidifier, the fan uses a quiet fan with a low sound, such as a volute centrifugal fan.

The water mist distributing pipe 2 is used for distributing water mist, and it is arranged on one side of the water tank 1 near the water tank 1 . In order to distribute the water mist generated by the vibration of the oscillating plate into the air, the water mist distribution pipe 2 is sealed and connected to the leak-proof cover 5 and communicated with the inner space of the leak-proof cover 5 . The water mist distributing pipe 2 is the only passage of the water mist, which realizes that the water mist can be distributed into the air without dripping water droplets around the humidifier.

The control mechanism of the humidifier is respectively connected with the ultrasonic oscillator 32 and the air supply mechanism 6 for controlling and controlling the operation of the humidifier. Its structure and circuit are conventional technologies, and its structure will not be described in detail here.

Because the water tank 1 and the base 4 in the prior art are connected by a baffle, that is, the bottom periphery of the water tank 1 is provided with a baffle, which is inserted on the base 4 through the baffle, the leak-proof cover 5 is combined with the baffle in this embodiment. Two into one, that is, the leak-proof cover 5 is also used as a baffle between the water tank 1 and the base 4, and the leak-proof cover 5 is inserted into the water tank 31 and the water tank 1 is placed on the base 4, which simplifies the structure of the humidifier. The shape of the leak-proof cover 5 is consistent with the shape of the upper part of the base 4 for insertion, and the outer wall of the leak-proof cover 5 and the inner wall of the base 4 that are plugged in each other are attached to each other, so as to reduce the gap between the two as much as possible.

As shown in Figures 1 and 2, in order to make the base 4 and the leak-proof cover 5 appear as an integral structure, the outer diameter of the upper part of the leak-proof cover 5 is greater than the outer diameter of the lower part, and the upper and lower parts of the leak-proof cover 5 pass through Step transition, the leak-proof cover 5 is inserted in the water tank 31 and then the step presses against the upper end surface of the water tank 31 . This structure also makes a loop structure formed between the leak-proof cover 5 and the wall of the water tank 31, and the water droplets after the condensation of water vapor between the leak-proof cover 5 and the water tank 31 can fall into the water tank 31 along the wall of the water tank 31 without flowing out of the water tank 31 edges, strengthen the anti-leakage function.

Claims (10)

1. a caisson is mentioned and is leaked and the anti-overflow humidifier, comprise that base, water tank, water smoke distribute pipe, be provided with ultrasonic water smoke in the described base and generate mechanism, wind pushing mechanism and controlling organization, described water tank bottom is provided with the Inlet and outlet water mouth of pipe that is used for water turnover water tank, it is characterized in that, the described Inlet and outlet water mouth of pipe is provided with the band seal plug and prevents the water blockoff device of overflow, and described ultrasonic water smoke generates in the mechanism and is provided with all-or-nothing piece; When water tank was installed on the base, all-or-nothing piece inserted to remove on the water blockoff device roof pressure seal plug and opens the Inlet and outlet water mouth of pipe; Mention water tank when leaving base, seal plug moves down and stops up the Inlet and outlet water mouth of pipe.

2. caisson according to claim 1 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described ultrasonic water smoke generates mechanism and is included in the tank that the base top is provided with, and described all-or-nothing piece is arranged in the tank, and corresponding up and down with the water blockoff device; Described water blockoff device is screwed onto on the Inlet and outlet water mouth of pipe of water tank.

3. caisson according to claim 2 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described water blockoff device comprises water blockoff device housing, the water blockoff bar that is screwed onto on the Inlet and outlet water mouth of pipe, and described water blockoff device housing has delivery port, and described seal plug is arranged on the water blockoff bar; Described water blockoff bar is set with the return spring of pretension, and described seal plug is inserted in the delivery port and at return spring effect lower seal delivery port.

4. caisson according to claim 3 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, be provided with guiding mechanism in the described water blockoff device housing, described water blockoff bar is inserted in the guiding mechanism and moves up and down along guiding mechanism and seals delivery port or open delivery port.

5. caisson according to claim 4 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described guiding mechanism comprises support bar, support bar one end is fixed on the water blockoff device housing, the other end or the support bar of support bar are provided with guide ring, delivery port on described guide ring and the water blockoff device housing is corresponding up and down, and described water blockoff bar is inserted in the guide ring, moves up and down under guide ring spacing.

6. caisson according to claim 3 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described water blockoff device housing is a tubular, have the groove that is spirally connected that a circle and the water tank Inlet and outlet water mouth of pipe are spirally connected on the end face on its top, the described groove that is spirally connected comprises inner ring side wall surface and outer ring side wall surface, and the screw-internal thread fit on the outer ring side wall surface in the external screw thread that the described Inlet and outlet water mouth of pipe is provided with and the groove that is spirally connected is spirally connected.

7. caisson according to claim 6 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, the bottom land of the described groove that is spirally connected has stopper slot, in the groove that is spirally connected, be placed with sealing ring, described sealing ring is provided with projection, and described projection is connected to and limits moving radially of sealing ring in the stopper slot.

8. mention according to any described caisson of claim 2-7 and leak and the anti-overflow humidifier, it is characterized in that, described bottom of gullet is provided with ultrasonator, described ultrasonator top is provided with the leakproof cover that is used to seal tank space, ultrasonator top, described leakproof cover periphery insert in the tank and do not have upstream face, described water smoke to distribute that the seal of tube is connected on the leakproof cover and with the leakproof cover in space UNICOM.

9. caisson according to claim 8 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described leakproof cover bottom outside wall surface and inboard wall of cistern face are fitted.

10. caisson according to claim 9 is mentioned and is leaked and the anti-overflow humidifier, it is characterized in that, described leakproof cover top external diameter is greater than lower outer diameter, and leakproof cover upper and lower is by step transition, and the leakproof cover is inserted in the tank then described step roof pressure on the upper surface of tank.

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