JP6788994B2 - Siphon drainage system - Google Patents

Description

The present invention relates to a siphon drainage system including a storage tank for temporarily storing and discharging wastewater.

For example, as shown in Patent Document 1, in a drainage system using the siphon force of a siphon drainage pipe, a storage tank is provided between the water supply device and the horizontal pulling pipe of the siphon drainage pipe, and the drainage from the water supply device is siphoned. There is known a configuration in which the water is temporarily stored in the storage tank until the start of the operation (see, for example, Patent Document 1).

JP 2013-209868

In the drainage system shown in Patent Document 1, for example, when drainage is performed from the bathtub, the drainage discharged from the bathtub flows into the storage tank. The drainage that has flowed into the storage tank flows through the horizontal pulling pipe of the siphon drainage pipe, and then flows into the vertical pipe.

In the siphon drainage pipe, the siphon force is not generated unless the vertical pipe is filled with drainage and falls in the vertical pipe. Therefore, until the siphon force is generated, the amount of drainage from the siphon drainage pipe flows into the storage tank. Since it is smaller than the amount of drainage from the storage tank, the water level of the drainage from the storage tank rises. After that, when the vertical pipe is filled with drainage and siphon force is generated, the amount of drainage by the siphon drainage pipe exceeds the amount of drainage of the drainage flowing into the storage tank, and the water level of the drainage decreases.

By the way, the siphon drain pipe in which the siphon force is generated quickly sucks the drainage in the storage tank, in other words, the suction force is large, so when the water level drops to some extent, the water surface near the siphon drain pipe sucks the drainage. The siphon drain pipe may drop close to the existing siphon drain pipe, and the siphon drain pipe may suck in the air inside the storage tank.

When the siphon drain pipe sucks in the air inside the storage tank together with the drainage, an abnormal noise may be generated, and this abnormal noise echoes in the air layer of the storage tank. When an abnormal noise is heard in the air layer of the storage tank, the wall surface of the storage tank may be vibrated, and finally the abnormal noise may be emitted to the outside of the storage tank.

In view of the above facts, an object of the present invention is to suppress noise from being heard in the storage tank.

The siphon drainage system according to claim 1 includes a storage tank for storing wastewater flowing in from the upstream, a horizontal pulling pipe connected to the storage tank and laterally discharging the drainage from the storage tank, and the lateral side. A vertical pipe that is arranged on the downstream side of the pull pipe and generates a siphon force by flowing down the drainage from the horizontal pull pipe, and a vertical pipe that is provided in the horizontal pull pipe and communicates with the outside of the storage tank. It has an air supply pipe having a length that allows air to flow into the horizontal pulling pipe and the drainage does not leak from the horizontal pulling pipe , and the bottom plate of the storage tank is directed to the horizontal pulling pipe side. It is tilted so that it goes down.

According to the siphon drainage system according to claim 1, when the wastewater flows into the storage tank, the wastewater is temporarily stored in the storage tank.
The drainage that has flowed into the storage tank flows into the vertical pipe through the horizontal pulling pipe, and when the full drainage falls in the vertical pipe due to gravity, a siphon force is generated. When the siphon force is generated, the drainage in the storage tank is sucked toward the vertical pipe, and the drainage becomes a full flow and flows down, so that the drainage can be performed quickly and efficiently.

By the way, when the drainage flows into the storage tank, the siphon force is not generated in the initial state where the vertical pipe is not yet full, so the siphon drainage is compared with the amount of drainage per unit time flowing into the storage tank. The amount of drainage from the pipe per unit time is small, and the drainage level rises in the storage tank.

Then, when the inside of the vertical pipe becomes full and a siphon force is generated, the inside of the horizontal pulling pipe becomes negative pressure, the drainage of the storage tank is sucked, the water level of the drainage of the storage tank begins to drop, and the water level of the drainage of the storage tank begins to drop, and the sideways through the air supply pipe. Air flows into the pull pipe.

Comparing the case where air flows into the horizontal pulling pipe through the air supply pipe and the case where air does not flow into the horizontal pulling pipe, the suction force for sucking the drainage in the storage tank is larger in the latter, and the suction power is higher. If it is large, the water surface of the drainage may be locally lowered to suck air and generate abnormal noise.

However, in the siphon drainage system of claim 1, the horizontal pulling pipe sucks air on the downstream side of the storage tank, so that the suction force acting on the drainage in the storage tank can be appropriately reduced. In the tank, sucking air from the opening of the horizontal drainage pipe is suppressed, and the generation of abnormal noise is suppressed inside the storage tank.
The "horizontal direction" of the "horizontal pulling pipe that discharges wastewater in the horizontal direction" is not limited to the horizontal direction, but also includes a slight inclination (for example, 5 degrees or less) .

The invention according to claim 2 is the siphon drainage system according to claim 1, wherein the siphon drainage system is provided with a vertical pipe arranged in a vertical direction in a building and the vertical pipes meet , and the air supply pipe has one end pulled horizontally. It communicates with the pipe and the other end is connected to the vertical pipe.

The sound generated when air and drainage are mixed may leak to the outside through the air supply pipe . By connecting the other end of the air supply pipe to the vertical pipe, the sound generated when air and drainage are mixed is released into the vertical pipe through the inside of the air supply pipe and is not released to the outside (atmosphere), so it is stored. The noise level outside the tank can be reduced.
The invention according to claim 3 comprises a ventilation pipe connected to the storage tank in the siphon drainage system according to claim 1, wherein one end of the air supply pipe communicates with the horizontal pulling pipe and the other end. It is connected to the ventilation pipe .

The invention according to claim 4 is the siphon drainage system according to claim 3, wherein the horizontal pulling pipe has an inclined portion in which a part on the storage tank side is inclined downward toward the downstream side in the drainage direction. The air supply pipe is provided on the storage tank side from the boundary between the inclined portion and the horizontal portion of the horizontal pulling pipe adjacent to the downstream side of the inclined portion.

After all the drainage in the storage tank is discharged, the siphon force of the vertical pipe acts on the drainage in the horizontal pulling pipe, but when air is sucked from the middle of the horizontal pulling pipe, from the position where the air is sucked. However, the suction power is weakened for the drainage remaining on the upstream side. If the horizontal pulling pipe on the upstream side of the position where air is sucked is horizontal, the drainage remaining in the horizontal portion is difficult to flow with a weak suction force, and as a result, the drainage tends to remain in the horizontal portion.

On the other hand, in the siphon drainage system of claim 4 , the portion of the horizontal pulling pipe from the connection portion with the air supply pipe to the storage tank side is inclined downward toward the downstream side in the drainage direction, so that the portion with the air supply pipe is used. The drainage remaining on the storage tank side from the connection portion can be flowed by its own weight to the downstream side in the drainage direction, and the drainage can be prevented from leaving the drainage from the connection portion of the horizontal pulling pipe with the air supply pipe to the storage tank side portion.

The invention according to claim 5 is the siphon drainage system according to any one of claims 1 to 4, wherein the joint connecting the horizontal pulling pipe and the air supply pipe is covered with a sound insulating material. There is.

In the siphon drainage system according to claim 5, since the joint connecting the horizontal pull pipe and the air supply pipe is covered with a sound insulating material, the joint may vibrate to insulate the abnormal noise emitted from the joint to the outside. it can.

According to the siphon drainage system of the present invention, it has an excellent effect that noise can be suppressed in the storage tank.

It is a side view which shows the whole structure of the siphon drainage system which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the storage tank of the siphon drainage system which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the storage tank which concerns on a comparative example. It is sectional drawing which shows the storage tank which lowered the water level of the drainage of the siphon drainage system which concerns on 1st Embodiment of this invention. It is a side view which shows the whole structure of the siphon drainage system which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the vicinity of the T-shaped joint of the siphon drainage system which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the storage tank of the siphon drainage system which concerns on 4th Embodiment of this invention.

[First Embodiment]
The siphon drainage system 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 4. The siphon drainage system 10 according to the present embodiment is a drainage system that efficiently discharges drainage from a water supply device by utilizing siphon force.

As shown in FIG. 1, a floor panel 16 is arranged on the upper side of the slab 14 of the building 12 at intervals from the slab 14. A water supply device 17 is arranged on the floor panel 16. The water supply device 17 is for draining drainage from a bathtub, a kitchen sink, a dishwasher, etc., but may be a wash basin, a bathroom waterproof pan, or the like.

One end of a pipe 18 for flowing drainage discharged from the water supply device 17 is connected to the water supply device 17. The pipe 18 is, for example, a pipe made of vinyl chloride, but may be made of another synthetic resin.

(Water tank)
As shown in FIG. 2, a storage tank 20 forming a part of the siphon drainage system 10 is arranged on the slab 14.
The storage tank 20 is formed in a box shape so that the drainage from the water supply device 17 can be temporarily stored. The storage tank 20 is a substantially rectangular parallelepiped, and the top plate 20A and the bottom plate 20B are inclined so as to be lowered toward the L direction side of the drawing. The storage tank 20 is made of a synthetic resin material such as vinyl chloride.

The other end of the pipe 18 is connected to one side wall 20C on the side of the storage tank 20 in the direction of arrow R in the drawing, and the drainage from the water supply device 17 is configured to flow into the storage tank 20.
One end of the pipe 22 is connected to the lower side of the other side wall 20D on the side in the direction of arrow L in the drawing facing the one side wall 20C of the storage tank 20.

Further, one end of the ventilation pipe 23 is connected to the top plate 20A of the storage tank 20. The other end of the ventilation pipe 23 is connected to the vertical pipe 28 (see FIG. 1) via a merging joint 30 (see FIG. 1) described later.
The pipe 22 and the ventilation pipe 23 are, for example, PVC pipes, but may be made of other synthetic resin.

The pipe 22 is inclined so as to be lowered toward the side of the arrow L. A T-shaped joint 24 is arranged on the other end side of the pipe 22. The T-shaped joint 24 is formed by connecting the first connection portion 24A to which the pipe 22 is connected, the second connection portion 24B arranged on the opposite side of the first connection portion 24A, the first connection portion 24A, and the second connection portion 24B. A third connecting portion 24C, which is arranged between them and extends upward at right angles to the direction connecting the first connecting portion 24A and the second connecting portion 24B, is provided. The first connection portion 24A and the second connection portion 24B are provided coaxially, and the center line CL of the first connection portion 24A and the second connection portion 24B is inclined so as to be lowered toward the arrow L direction side. ing. The third connection portion 24C corresponds to the ventilation portion of the present invention. The T-shaped joint 24 is made of, for example, vinyl chloride, but may be made of another synthetic resin.

(Siphon drainage pipe)
A horizontal pull pipe 26A of the siphon drainage pipe 26, which forms a part of the siphon drainage system 10, is connected to the second connection portion 24B of the T-shaped joint 24. A part of the horizontal pulling pipe 26A in the vicinity of the T-shaped joint 24 is inclined, but the downstream side thereof is arranged on the slab 14 with no slope in the lateral direction. As shown in FIG. 1, a vertical pipe 26B extending downward (vertically downward) is continuous at the downstream end of the horizontal pulling pipe 26A.
The siphon drain pipe 26 of the present embodiment is made of polybutene, but may be made of another flexible synthetic resin.

In the present embodiment, the horizontal pulling pipe 26A, the section between the first connecting portion 24A and the second connecting portion 24B of the T-shaped joint 24, and the pipe 22 correspond to the horizontal pulling pipe of the present invention.

The building 12 is provided with a vertical pipe 28 extending in the vertical direction. A merging joint 30 is attached to the vertical pipe 28, and the drainage flowing through the siphon drain pipe 26 is discharged to the vertical pipe 28 via the merging joint 30.

An air supply pipe 32 extending upward is connected to the third connection portion 24C of the T-shaped joint 24, and the inside of the T-shaped joint 24 communicates with the outside by the air supply pipe 32.
(Action, effect)
Next, the operation and effect of the siphon drainage system 10 of the present embodiment will be described.
When the drainage from the water supply device 17 is discharged from the pipe 18, the drainage flows into the storage tank 20.

Since the bottom plate 20B of the storage tank 20 is inclined so that the siphon drainage pipe 26 side is lower than the pipe 18 side into which the drainage flows, the drainage is discharged from the pipe 18 side into the storage tank 20. It flows to the 26 side and starts to accumulate from the siphon drain pipe 26 side, and the water depth on the siphon drain pipe 26 side becomes deeper than that on the pipe 18 side.

Then, as the drainage flows into the storage tank 20 and the water level of the drainage in the storage tank 20 rises, the air in the storage tank 20 is pushed and the ventilation pipe 23 connected to the top plate 20A of the storage tank 20. And the water is discharged to the vertical pipe 28 via the merging joint 30. As a result, drainage can be quickly and efficiently flowed into the storage tank 20.

The drainage that has flowed into the storage tank 20 flows into the siphon drainage pipe 26 via the pipe 22 and the T-shaped joint 24, and when the full-flow drainage falls in the vertical pipe 26B due to gravity, the potential energy of the siphon head Hs -By, siphon force is generated. When the siphon force is generated, the drainage in the storage tank is sucked toward the vertical pipe 26B, and the drainage becomes a full flow and flows down, so that the drainage is efficiently performed.

By the way, at the stage when the drainage flows into the storage tank 20, in the initial state where the inside of the vertical pipe 26B of the siphon drain pipe 26 is not yet full, the siphon force is not generated, so the unit time for flowing into the storage tank 20. The amount of drainage per unit time by the siphon drainage pipe 26 is smaller than the amount of drainage per unit time, and the drainage water level rises in the storage tank 20.

Then, when the inside of the vertical pipe 26B of the siphon drain pipe 26 becomes full and a siphon force is generated, the drainage of the storage tank 20 is sucked and the water level of the drainage of the storage tank 20 begins to drop.

Here, the siphon drainage system 100 of the comparative example will be described with reference to FIG. The same components as those in the present embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 3, in the siphon drainage system 100 of the comparative example, the air supply pipe 32 is not provided, and the horizontal pulling pipe 26A of the siphon drainage pipe 26 is directly connected to the side wall 20D of the storage tank 20. There is.

In the siphon drainage system 100 of this comparative example, when the water level of the drainage in the storage tank 20 drops to near the height of the opening portion of the horizontal pulling pipe 26A, the amount of drainage suction per unit time of the siphon drainage pipe 26 due to the siphon force increases. Since it is very large, the water surface near the opening portion of the horizontal pulling pipe 26A is partially lowered, and the horizontal pulling pipe 26A sucks the air in the storage tank 20, and in the storage tank 20, for example, a strange noise N May occur. Then, the abnormal noise N resonates in the air layer of the storage tank 20 to vibrate the wall surface of the storage tank 20, and the abnormal noise N may be emitted to the outside of the storage tank 20.

On the other hand, in the siphon drainage system 10 of the present embodiment, as shown in FIG. 4, when the water level of the drainage of the storage tank 20 drops (the same height as the comparative example), the siphon force (suction force) generated in the vertical pipe 26A ) Causes a negative pressure inside the T-shaped joint 24 of the third connecting portion 24C, and the air supply pipe 32 sucks in the air A under the floor. Since the siphon drain pipe 26 sucks air A (air outside the storage tank 20) on the downstream side of the storage tank 20, the suction force acting on the drainage in the storage tank 20 is appropriately reduced, so that the storage tank Inside the 20th, it is possible to prevent the water surface in the vicinity of the opening portion of the pipe 22 from being partially lowered and sucking in the air in the storage tank 20.

Therefore, it is possible to suppress the generation of abnormal noise caused by the suction of air in the storage tank 20, and since the abnormal noise does not reverberate in the storage tank 20, the wall surface of the storage tank 20 vibrates. It is also suppressed that abnormal noise is emitted to the outside of the storage tank 20. In this way, in the siphon drainage system 10 of the present embodiment, the propagation of noise during drainage to the indoor environment is suppressed.

When the siphon drain pipe 26 sucks the air A through the air supply pipe 32, an abnormal noise is generated by the air mixed in the drainage inside the T-shaped joint 24, and the siphon drain pipe 26 passes through the inside of the air supply pipe 32. An abnormal noise may be emitted to the outside of the air supply pipe 32. However, the level of the abnormal noise generated inside the T-shaped joint 24 is very small as compared with the abnormal noise reverberating in the storage tank 20 as in the comparative example. Further, the abnormal noise generated inside the T-shaped joint 24 is blocked by the drainage that is full flow inside the pipe 22 and does not propagate to the air layer in the storage tank 20, so that the noise is not propagated in the storage tank 20. In the air layer, the abnormal noise generated inside the T-shaped joint 24 does not resonate.

As shown in FIG. 2, the portion P where the air sucked from the air supply pipe 32 comes into contact with the drainage, in other words, the center line CL of the first connection portion 24A and the second connection portion 24B and the center line of the second connection portion 24C. The distance DL from the intersection of the above to the inner surface of the storage tank 20 may be set so that the drainage path between the above-mentioned part P and the storage tank 20 becomes full with drainage at the time of drainage, so that the distance DL becomes short. The pipe 22 may be abolished and the T-shaped joint 24 may be directly connected to the storage tank 20, or the pipe 22 may be longer than in FIG. 2 so that the distance DL becomes longer. In other words, when the drainage is discharged from the storage tank 20, the distance DL may be set so as to suppress the inhalation of air in the storage tank 20, which is the cause of the generation of abnormal noise echoing in the storage tank 20.

By the way, even after all the drainage in the storage tank 20 is discharged, the siphon force of the vertical pipe 26B is applied to the drainage remaining in the horizontal pulling pipe 26A until the drainage in the vertical pipe 26B is completely dropped. Works. However, if air is sucked in the middle of the drainage path on the downstream side of the storage tank 20, the suction force becomes weaker for the drainage remaining in the drainage path on the upstream side of the position where the air is sucked. It ends up. Therefore, if the drainage path on the upstream side of the position where air is sucked is horizontal, the drainage remaining in the horizontal part is difficult to flow to the downstream side with a weak suction force, and as a result, the drainage remains in the horizontal part. It will be an easy situation.

In the siphon drainage system 10 of the present embodiment, since the drainage path on the storage tank 20 side from the portion P where the air sucked from the air supply pipe 32 comes into contact with the drainage is inclined toward the downstream side in the drainage direction, the air supply pipe 32 The drainage remaining in the drainage path on the storage tank 20 side from the portion P where the air sucked from is in contact with the drainage flows by its own weight toward the downstream side in the drainage direction, and drains from the portion P to the portion on the storage tank 20 side. Can be avoided.

The portion P where the sucked air comes into contact with the drainage is a portion where the drainage path is inclined as in the present embodiment, or a boundary SP between the inclined portion 26Aa and the horizontal portion 26Ab of the horizontal pulling pipe 26A, in other words, It is preferably provided at the upstream end of the horizontal portion 26b.

The length of the air supply pipe 32 is not particularly limited, but the air supply pipe 32 may be omitted as long as the drainage does not leak to the outside.

[Second Embodiment]
The siphon drainage system 10 according to the second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, in the siphon drainage system 10 according to the present embodiment, the air supply pipe 32 connected to the T-shaped joint 24 is formed longer than that of the first embodiment, and the end portion of the air supply pipe 32 is formed. Is connected to the merging joint 30. In the present embodiment, the air supply pipe 32 sucks the air in the vertical pipe 28.

In the siphon drainage system 10 according to the present embodiment, the abnormal noise generated inside the T-shaped joint 24 is emitted to the inside of the vertical pipe 28 through the inside of the air supply pipe 32, so that it cannot propagate indoors. It can be suppressed.

[Third Embodiment]
The siphon drainage system 10 according to the third embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 6, in the siphon drainage system 10 according to the present embodiment, the T-shaped joint 24 is covered with the sound insulating material 34.
The sound insulating material 34 is, for example, rubber or the like in which the side in contact with the T-shaped joint 24 is formed of a porous (sponge-like) cushion material 36 such as urethane or polyethylene, and the side opposite to the T-shaped joint 24 has no voids. A sheet-like or strip-shaped material formed of the elastic body 38 of the above can be used. The sound insulation material 34 is not limited to the structure of the present embodiment, and any known commercially available sound insulation material can be used as long as it can insulate sound.

When the abnormal noise (vibration of air) generated inside the T-shaped joint 24 passes through the third connection portion 24C, the third connection portion 24C is vibrated, and the third connection portion 24C vibrates. An abnormal noise may be emitted from the third connection portion 24C toward the outside. However, in the T-shaped joint 24 of the present embodiment, not only the third connection portion 24C but also the entire T-shaped joint 24 is covered with the sound insulating material 34, so that abnormal noise emitted from the T-shaped joint 24 can be heard. Sound is insulated by the sound insulating material 34, and the emission of abnormal noise emitted from the T-shaped joint 24 into the underfloor can be suppressed.
When the air supply pipe 32, the pipe 22, and the horizontal pulling pipe 26A vibrate, the air supply pipe 32, the pipe 22, and the horizontal pulling pipe 26A may be covered with the sound insulating material 34, if necessary. Further, the T-shaped joint 24, the air supply pipe 32, and the pipe 22 may be changed from resin to metal so as not to vibrate easily.

[Fourth Embodiment]
The siphon drainage system 10 according to the fourth embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
The inside of the storage tank 20 of the present embodiment is substantially divided into three chambers by two partition walls 40. The upper part of each room is connected. Water-related appliances 17A, 17B, and 17C are connected to the storage tank 20 via the pipe 18, and a siphon drain pipe 26 is connected to the storage tank 20 via the pipe 22 and the T-shaped joint 24. It is connected.
In the storage tank 20 of the present embodiment, the inside is divided into three chambers, but the number of compartments can be increased or decreased as appropriate.

[Other Embodiments]
Although an example of the embodiment of the present invention has been described, the present invention is not limited to such an embodiment, and various other embodiments are possible within the scope of the present invention.

In the above embodiment, the horizontal pull pipe 26A of the siphon drain pipe 26 is connected to the storage tank 20 via the T-shaped joint 24 and the pipe 22, but the end of the horizontal pull pipe 26A is directly connected to the storage tank 20. You may. In this case, a hole may be machined in the horizontal pulling pipe 26A, and the air supply pipe 32 may be connected to the machined hole.

The storage tank 20 has a rectangular box shape, but the storage tank 20 is not limited to the rectangular box shape, and may have another shape such as a cylindrical shape having a circular cross section with both ends closed.

In the second embodiment, the end of the air supply pipe 32 is connected to the merging joint 30, but the end of the air supply pipe 32 may be connected to the ventilation pipe 23. Also in this embodiment, the air supply pipe 32 can suck the air in the vertical pipe 8 through the ventilation pipe 23.

10 ... Siphon drainage system, 12 ... Building (building), 20 ... Storage tank, 26A ... Horizontal pipe, 26Aa ... Inclined part, 26Ab ... Horizontal part, 26B ... Vertical pipe, 24C ... Third connection part (ventilation part) , 28 ... Standing pipe, 32 ... Air supply pipe, 34 ... Sound insulation material

Claims (5)

A water tank that stores wastewater that has flowed in from the upstream,
A horizontal pulling pipe that is connected to the storage tank and discharges the drainage from the storage tank in the lateral direction.
A vertical pipe arranged on the downstream side of the horizontal pulling pipe and generating a siphon force by flowing down the drainage from the horizontal pulling pipe.
An air supply pipe having a length that is provided in the horizontal pulling pipe and communicates with the outside of the storage tank so that air can flow into the inside of the horizontal pulling pipe and the drainage does not leak from the horizontal pulling pipe. ,
Have,
A siphon drainage system in which the bottom plate of the storage tank is inclined so as to be lowered toward the horizontal pulling pipe side. It is arranged vertically in the building and is equipped with a vertical pipe where the vertical pipes join .
The siphon drainage system according to claim 1, wherein one end of the air supply pipe communicates with the horizontal pull pipe and the other end is connected to the vertical pipe . Equipped with a ventilation pipe connected to the storage tank
The siphon drainage system according to claim 1, wherein one end of the air supply pipe communicates with the horizontal pulling pipe and the other end is connected to the ventilation pipe. The horizontal pulling pipe has an inclined portion in which a part on the storage tank side is inclined downward toward the downstream side in the drainage direction.
The siphon drainage system according to claim 3, wherein the air supply pipe is provided on the storage tank side from the boundary between the inclined portion and the horizontal portion of the horizontal pulling pipe adjacent to the downstream side of the inclined portion. The siphon drainage system according to claim 3 or 4, wherein the joint connecting the horizontal pulling pipe and the air supply pipe is covered with a sound insulating material.