JP7526437B2 - Check valve - Google Patents

Description

The present invention relates to a check valve for pipes that form a flow path for fluids such as gases or liquids, or for drainage outlets into which wastewater flows, allowing the fluid inside the pipes to flow unimpeded from upstream to downstream while preventing backflow from downstream to upstream.

Conventionally, piping structures that combine pipes and joint members to pass fluids such as liquids and gases and to perform drainage, exhaust, etc. have been known. These piping structures are designed to pass gases or liquids from upstream to downstream, but there are cases where the gas or liquid flows back due to a large amount of gas or liquid being produced in the downstream piping. Gas or liquid discharged downstream may become contaminated with filth or dangerous substances during the discharge process, and it is undesirable for such contaminated fluids to flow back and contaminate the inside of the piping or overflow into the inlet source.

Therefore, a structure has been proposed that prevents backflow of fluid by using a piping check valve, as described in Patent Document 1, which allows fluid to flow unimpeded from upstream to downstream within the piping while preventing backflow from downstream to upstream.
The check valve fitting equipped with the check valve described in Patent Document 1 is a fitting member used for drainage piping that allows drainage, which is a fluid, to pass through, and is composed of a fitting body and a check valve unit described below.
The fitting body consists of a tubular portion that forms a fluid flow path, connection portions provided at the upstream and downstream ends of the tubular portion, a storage portion provided within the tubular portion, and an opening that communicates with the storage portion provided on the side of the pipe portion.
The check valve unit is composed of a valve body, a check valve unit body, and a locking member, which will be described below.
The valve body is composed of a disk-shaped valve body portion and a valve stem portion disposed substantially perpendicular to the valve body portion.
The check valve unit main body is a roughly plate-shaped member with a lid portion on the side, with packing on the side of the lid portion, a drainage flow path in the central portion, a valve seat portion that abuts the valve body portion around the drainage flow path, and a fixing portion that fixes the valve shaft portion in the center of the flow path.
The locking member is a disk-shaped member that is rotatably attached to the lid portion of the check ring valve unit body and has a rotation lock structure on its side that fits into the opening of the coupling member when rotated.

The check valve joint is installed on a drainage pipe as follows.
The connection part at the upper end of the joint body is connected to the upstream pipe, and the connection part at the lower end is connected to the downstream pipe.
Next, the check valve unit is inserted through the opening of the fitting body and placed inside the fitting body so that the lid portion closes the opening. The opening of the fitting body and the locking member are then rotated to close the opening with a rotation lock, and the check valve unit is installed on the drainage piping.
When drainage is performed from the upstream side, the drainage enters the coupling body from the upstream piping and flows into the valve body. When a certain amount of drainage accumulates in the valve body or in the coupling body upstream of the valve body, the valve body elastically deforms due to the pressure of the accumulated drainage, and the valve body separates from the valve seat to open the flow path, allowing the drainage accumulated inside to flow out, pass through the coupling member, and be discharged into the downstream piping.
On the other hand, if wastewater flows back from the downstream side, the valve body and the valve seat are forced closer to each other due to the pressure of the backflowing wastewater, reliably blocking the flow path, so that the wastewater cannot pass through the valve body and backflow of the wastewater is prevented.
Furthermore, if maintenance or cleaning of the check valve fitting is required, the check valve unit can be removed by releasing the rotation lock between the locking member and the opening and performing maintenance, cleaning, etc. After the necessary work is completed, the check valve unit body can be reinserted from the opening and the locking member and opening are reconnected with the rotation lock, allowing the drainage piping to be used without hindrance.

JP 2019-148129 A

In a check valve that normally blocks the flow path and opens only when a fluid is allowed to pass as described above, in order to configure it so that it opens even when the pressure of the fluid from upstream to downstream is small, that is, even when the amount of fluid is small, it is necessary to reduce the pressure at which the valve body contacts the valve seat. A check valve that reliably opens in response to such a small pressure is often configured to be compact overall, for example by reducing the contact point between the valve body and the valve seat, but in this case, the flow path through which the fluid passes is also small, and the fluid processing performance deteriorates.
However, when the opening of the flow path is enlarged to quickly process a large amount of fluid, the valve body and valve seat that block the flow path also become larger, and in order to reliably block the entire enlarged contact point, the pressure when the valve body contacts the valve seat must be sufficiently large. As a result, when the amount of fluid flowing from upstream to downstream is small and the acting pressure is low, the valve body does not separate from the valve seat, resulting in a check valve that does not open.
In other words, the check valve described in Patent Document 1 can only choose between easily opening a flow path but having low fluid processing performance, or having high fluid processing performance but not opening the flow path unless the fluid pressure becomes high, and it was not possible to create a check valve that easily opens a flow path and has high fluid processing performance.
The present invention has been invented in consideration of the above problems, and provides a check valve that is configured to constantly close a flow path, and that can easily open even with only a small amount of fluid from upstream, and can quickly deal with a large amount of fluid even if it is produced.

The invention described in claim 1 is
a valve body that prevents the passage of fluid from a downstream side by contacting the valve seat;
the valve body includes a valve disc portion made of a substantially plate-shaped elastically deformable material abutting on the valve seat portion, and a valve stem portion extending in a direction of the flow path, the valve stem portion being disposed within the flow path so as to be movable forward and backward in the direction of the flow path, and the valve body is biased so as to abut on the valve seat portion,
This check valve is characterized by comprising: an opening/closing mechanism in which, due to pressure on the valve body when a fluid flows, the valve body elastically deforms and separates from the valve seat , allowing fluid from the upstream side to pass through and achieving a first open state; and an expansion mechanism in which, when the opening/closing mechanism is open , due to pressure on the valve body when a fluid flows, the valve body moves in a direction in which the valve body separates from the valve seat, thereby achieving a second open state in which the flow path is wider than the first open state.

The present invention as set forth in claim 2 is
2. The check valve according to claim 1 , wherein the check valve is provided inside a joint member having a cylindrical tubular body portion.

The present invention as defined in claim 3 is
3. The check valve according to claim 2 , wherein an opening is provided on a side surface of the tubular body portion, and the check valve is configured to be detachable from the opening.

The present invention as set forth in claim 4 is
The check valve according to any one of claims 1 to 3 , wherein the check valve is provided at a drain outlet for draining water from a floor surface.

In the invention described in claim 1, the check valve has a first opening state in which it opens when a small amount of fluid is to be treated, and a second opening state in which it quickly treats a large amount of fluid. This makes it possible to provide a check valve that easily opens even when there is a small amount of fluid from upstream, and can quickly treat a large amount of fluid. In addition , the configuration of the check valve can be clarified.
In the check valves according to claims 2 and 3 , the check valve can be disposed within the flow path of the drainage piping, making it easy to utilize the check valve.
In the check valve according to the fourth aspect of the present invention, the check valve can be disposed on the piping of the flow path of the drainage piping on the floor surface, and the check valve can be easily utilized.

FIG. 2 is a cross-sectional view showing the construction state of the first embodiment. 2 is a cross-sectional view showing a first open state of the check valve of FIG. 1. FIG. FIG. 2 is a cross-sectional view showing a second open state of the check valve of FIG. 1 . FIG. 2 is a cross-sectional view showing the check valve unit of the first embodiment with the check valve unit removed. FIG. 2 is a cross-sectional view showing a component configuration of the first embodiment. FIG. 11 is a cross-sectional view showing the construction state of the second embodiment. FIG. 7 is a cross-sectional view showing the check valve unit of FIG. 6 . 8 is a cross-sectional view showing a first open state of the check valve unit of FIG. 7. FIG. 8 is a cross-sectional view showing a second open state of the check valve unit of FIG. 7. FIG. FIG. 11 is a cross-sectional view showing the component configuration of a check valve unit according to a second embodiment.

A first embodiment of the present invention will be described below with reference to the drawings. The drainage piping using the check valve joint of the first embodiment of the present invention shown in Figures 1 to 5 is composed of a joint body 1 and a check valve unit 2 described below, and is installed in an upstream pipe P and a downstream pipe P.
The fitting body 1 consists of a straight tubular body section 1a which forms a flow path for the fluid, a storage section 1b which is provided inside the tubular body section 1a and which communicates with the upstream and downstream piping P, and an opening section 1c which is provided on the side of the tubular body section 1a and which communicates with the storage section 1b.
The check valve unit 2 is composed of a valve body 4, a check valve unit body 3, and a lock member 5, which will be described below.
The valve body 4 is composed of a disk-shaped valve body 4a made of an elastic material and a valve stem 4b that is provided perpendicular to the valve body 4a from the center of the valve body 4a. The valve body 4 is generally called an umbrella valve because it has an umbrella-like shape.
Further, a stopper member 4c is provided at the end of the valve shaft portion 4b to prevent a spring member 7 (described later) from coming off in a state in which the spring member 7 is disposed around the valve shaft portion 4b.
The check valve unit body 3 is a generally cylindrical member having a lid 3a on the side that closes the opening 1c, and the upstream surface of the plate-like portion has an abutment surface with the storage portion 1b, and this abutment surface and the side of the lid 3a are provided with packing. The cylindrical portion forms a circular water passage 3e that serves as a drainage flow path, and has a valve seat 3c around the downstream surface of the water passage 3e. The valve seat 3c is composed of an attachment portion 3d having a through hole in the center, through which the valve shaft portion 4b is arranged so as to be able to advance and retreat along the axial direction of the water passage 3e, i.e., the drainage flow path direction, and an arm extending from the attachment portion 3d to the inner surface of the water passage 3e. Note that the arm is not shown in Figures 1 to 5 because it is hidden by the attachment portion 3d and is located in an invisible position. Furthermore, when installation is completed, a spring member 7 is provided between the valve stem 4b and the mounting portion 3d, which urges the valve stem 4b so that the valve body 4a moves toward the valve seat 3c. The spring member 7 acts in the extension direction between the stopper member 4c at the end of the valve stem 4b and the mounting portion 3d, and as a result, the valve body 4 is moved in the direction in which the valve body 4a abuts against the valve seat 3c.
In addition, the cover portion 3a is disk-shaped and is formed integrally with the side of the check valve unit main body 3, and is provided with an annular packing on the side of the disk portion and is configured to close the opening 1c of the joint main body 1 after installation is completed.
The locking member 5 is a disk-shaped member that is rotatably attached to the lid portion 3a of the check valve unit main body 3. When installation is completed, it rotates and locks into the opening 1c of the fitting main body 1, thereby storing the valve body 4 and valve seat portion 3c of the check valve unit main body 3 in the storage portion 1b inside the fitting main body 1, and also functions to maintain and fix the lid portion 3a in a state in which the opening 1c is closed.
Before being transported to a construction site, the check valve unit body 3 has the valve stem 4b inserted into the through-hole of the attachment part 3d from the valve seat 3c side (downstream side), and a spring member 7 is disposed around the valve stem 4b using a stopper member 4c to bias the valve stem 4b so that the valve body 4a abuts against the valve seat 3c. In addition, the lock member 5 is rotatably attached to the lid 3a of the check valve unit body 3.
In this embodiment, when the pressure of the fluid, i.e., the drainage water, acts on the flow path in the valve seat 3c from the upstream side, the valve body 4a of the valve body 4 first elastically deforms and separates from the valve seat 3c, allowing the drainage water to pass. Then, when the pressure of the drainage water increases to a predetermined level exceeding the pressure at which the valve body 4a elastically deforms, the spring member 7 provided on the valve shaft 4b contracts, and the valve shaft 4b moves downstream, expanding the flow path for the drainage water.
In other words, the check valve of this embodiment is a check valve that is equipped with an opening and closing mechanism in which, when pressure is applied to the valve body 4a as the fluid flows, the valve body 4 elastically deforms, separating it from the valve seat 3c and opening the flow path, and further equipped with an expansion mechanism in which, when pressure is applied to the valve body 4a as the fluid flows, the valve body 4 moves in the direction in which the valve body 4a moves away from the valve seat 3c, widening the flow path, and is configured so that the fluid pressure at which the spring member 7 begins to contract is greater than the fluid pressure at which the valve body 4a begins to elastically deform.

The check valve is installed on a drainage pipe as follows.
The upper end of the joint body 1 is connected to the upstream pipe P, and the lower end is connected to the downstream pipe P, respectively.
Next, the check valve portion (the valve body 4 and the valve seat 3c portion) of the check valve unit 2 is inserted through the opening 1c of the fitting body 1, and the valve body 4 and the valve seat 3c portion are positioned inside the fitting body 1. The opening 1c of the fitting body 1 is then closed with the lid portion 3a, and the locking member 5 and the opening 1c are further engaged and closed with a rotation lock, thereby installing the check valve in the drainage piping.

In the drainage pipe equipped with the check valve configured as described above, when there is no drainage, the valve body 4 abuts against the valve seat portion 3c, as shown in FIG. 1, to block the drainage flow path.
At this time, the valve body 4 is biased by the spring member 7 in a direction in which the valve body 4a abuts against the valve seat 3c.
When wastewater backflows from the downstream side, the valve body 4a and the valve seat 3c come closer together due to the water pressure of the backflow water applied from the downstream side, and the flow path is closed reliably, so that the wastewater cannot pass through the check valve and the backflow of the wastewater is prevented. In addition, since the valve body 4a and the valve seat 3c are in contact even when there is no wastewater, it is possible to prevent odors and pests from the downstream side from flowing back to the upstream side.

When drainage is performed from the upstream side, the drainage enters the fitting body 1 from the upstream piping P and flows into the water passage 3e of the check valve unit body 3 and onto the valve body 4a. When a certain amount of drainage accumulates on the water passage 3e of the check valve unit body 3 or in the fitting body 1 upstream of the valve body 4, the pressure of the accumulated drainage elastically deforms the valve body 4a and separates it from the valve seat 3c as shown in Figure 2, opening the drainage flow path, and the drainage accumulated inside the check valve unit body 3 and fitting body 1 flows out, passes through the water passage 3e of the check valve unit body 3, and is discharged into the downstream piping P.

If the amount of drainage is small and the drainage pressure is not enough to cause elastic deformation of the spring member 7, when drainage is complete, the elasticity of the valve body 4a causes the valve body 4a to return to the shape shown in FIG. 1, and the valve body 4a comes into contact with the valve seat 3c again, blocking the drainage flow path.

On the other hand, even if a large amount of water is discharged and the valve body 4a is elastically deforming to treat the water, if the pressure of the water discharge received by the valve body 4 is so high that the spring member 7 on the flow path contracts against the bias of the spring member 7, the spring member 7 contracts as shown in Fig. 3, and the valve body 4a and the valve seat 3c are separated further by the length of the contracted spring member 7, thereby expanding the separated flow path for the separated water discharge. By expanding the flow path for the water discharge, the performance of the joint member for treating the water discharge is improved, and the water discharge can be treated quickly.
When the drainage process is completed and the water pressure in the flow path decreases, the water pressure received by the valve body 4a of the check valve decreases, and the pressure is no longer enough to cause the spring member 7 to contract, the spring member 7 expands and returns to its original position, and only the valve body 4 elastically deforms to return to the state in which the flow path is open, as shown in Figure 2. Thereafter, when the drainage is completed, the elasticity of the valve body 4a causes the valve body 4a to return to the shape shown in Figure 1, and the valve body 4a comes into contact with the valve seat 3c again, blocking the drainage flow path.

When maintenance or cleaning is required for the above check valve fitting, the rotation lock between the locking member 5 and the opening 1c can be released, and the check valve unit 2 can be removed as shown in Figure 4 to perform maintenance or cleaning. After the necessary work is completed, the check valve unit body 3 can be reinserted through the opening 1c, and the locking member 5 and opening 1c can be connected with the rotation lock, allowing the drainage piping to be used without hindrance.

Next, a second embodiment of the present invention will be described with reference to the drawings. The drain piping using the check valve of the second embodiment of the present invention shown in Figures 6 to 10 relates to a drain provided on a floor surface where drainage occurs frequently during use, cleaning, etc. in a building, such as the floor surface of a toilet room, and is composed of a floor drain 6, a check valve unit 2, and a piping P under the floor, which will be described below.
A toilet room is a room in a building that is equipped with sanitary equipment such as a toilet, and its floor surface is made of a water-resistant material such as tiles, and the floor surface is gently sloped toward a floor drain 6 provided on the floor surface. When cleaning the toilet room, cleaning water may be run on the floor surface to wash away dirt adhering to the floor surface.
The floor drain 6 is an opening provided in the floor surface of the toilet room, and is configured so that the check valve unit 2 can be detachably connected thereto.
As shown in Figure 6, the underfloor piping P is a drainage piping installed in the underfloor space of the toilet room, and consists of a pipe body arranged horizontally with a slight downward slope and an elbow pipe bent upward at its end, and the upper end of the elbow pipe is connected to the lower end of the floor drain outlet 6.
The check valve unit 2 is composed of a valve body 4 and a check valve unit body 3, which will be described below.
The valve body 4 is composed of a disk-shaped valve body 4a made of an elastic material and a valve stem 4b that is provided perpendicular to the valve body 4a from the center of the valve body 4a. The valve body 4 is generally called an umbrella valve because it has an umbrella-like shape.
Further, a stopper member 4c is provided at the end of the valve shaft portion 4b to prevent a spring member 7 (described later) from coming off in a state in which the spring member 7 is disposed around the valve shaft portion 4b.
The check valve unit main body 3 is a member having an approximately cylindrical shape, and has a circular water passage 3e inside which serves as a drainage flow path, as well as a valve seat portion 3c around the downstream surface of the water passage 3e.
The valve seat 3c is composed of a mounting portion 3d having a through hole in the center thereof through which the valve stem 4b is arranged so as to be able to advance and retreat along the axial direction of the water passage 3e, i.e., the flow direction of the wastewater, and an arm extending from the mounting portion 3d to the inner surface of the water passage 3e. Note that the arm is not shown in Figures 6 to 10 because it is hidden by the mounting portion 3d and is located in an invisible position. Furthermore, a spring member 7 is provided between the valve stem 4b and the mounting portion 3d to bias the valve stem 4b so that the valve body 4a moves toward the valve seat 3c when construction is completed.
The spring member 7 acts in an expanding direction between the stopper member 4c at the end of the valve shaft portion 4b and the mounting portion 3d, thereby moving the valve body 4 in a direction in which the valve disc portion 4a abuts against the valve seat portion 3c.
When in use, the check valve unit 2 connected to the floor drain 6 is configured so that the outer surface of the check valve unit body 3 is watertightly connected to the inner surface of the floor drain 6.
In this embodiment, when the pressure of the fluid, i.e., the drainage water, acts on the flow path in the valve seat 3c from the upstream side, the spring member 7 provided on the valve shaft 4b first contracts, and the valve shaft 4b moves downstream, causing the valve body 4a to separate from the valve seat 3c and allow the drainage water to pass. Then, when the pressure of the drainage water increases to a predetermined level exceeding the pressure at which the spring member 7 elastically deforms and contracts, the valve body 4a of the valve body 4 elastically deforms in the direction away from the valve seat 3c, and the drainage water flow path expands.
In other words, the check valve of the present embodiment is a check valve that is equipped with an opening/closing mechanism in which the valve body 4 moves in the direction in which the valve body 4a moves away from the valve seat 3c due to the pressure on the valve body 4a when the fluid flows, thereby opening the flow path, and further equipped with an expansion mechanism in which the valve body 4a elastically deforms in the direction in which it moves away from the valve seat 3c due to the pressure on the valve body 4a when the fluid flows, thereby widening the flow path, and is configured so that the pressure of the fluid at which the valve body 4a begins to elastically deform is greater than the pressure of the fluid at which the spring member 7 begins to contract.

In a toilet room configured as described above, when there is no drainage, as shown in Figure 6 or Figure 7, the valve body 4 in the floor drain 6 abuts against the valve seat portion 3c, blocking the drainage flow path.
At this time, the valve body 4 is biased by the spring member 7 in a direction in which the valve body 4a abuts against the valve seat 3c.
When wastewater backs up from the downstream side of the underfloor piping P, the valve body 4a and the valve seat 3c come closer together due to the water pressure of the backflow water applied from the downstream side, ensuring the blockage of the flow path, preventing the wastewater from passing through the check valve and preventing the backflow of the wastewater. In addition, because the valve body 4a and the valve seat 3c are in contact even when there is no wastewater, it is possible to prevent odors and pests from the downstream side from backflowing to the upstream side.

When drainage occurs on the floor of the toilet room due to reasons such as cleaning the toilet room, the drainage flows from above the floor into the floor drain port 6. When drainage is performed in this way into the floor drain port 6, the drainage flows into the valve body portion 4a on the water passage 3e of the backflow prevention valve unit main body 3. When a certain amount of drainage accumulates in the water passage 3a upstream of the valve body 4, the spring member 7 elastically deforms and contracts due to the pressure of the accumulated drainage, as shown in FIG. 8, and the valve shaft portion 4b moves in the direction in which the valve body portion 4a moves away from the valve seat portion 3c. As a result, the entire valve body 4 moves, and the valve body portion 4a moves away from the valve seat portion 3c, opening the drainage flow path, and the drainage accumulated inside the backflow prevention valve unit main body 3 and the joint main body 1 flows out, passes through the water passage 3e of the backflow prevention valve unit main body 3, and is discharged into the downstream piping P.

If the amount of drainage is small and the drainage pressure is not enough to cause elastic deformation of the valve body 4a, when drainage is complete, the water pressure of the drainage is released, the spring member 7 expands again, and the valve shaft 4b moves in the direction in which the valve body 4a abuts against the valve seat 3c, causing the valve body 4 to return to the position shown in Figure 7, and the valve body 4a abuts against the valve seat 3c again, blocking the drainage flow path.

On the other hand, even if a large amount of wastewater is discharged, for example by pouring wastewater collected in a bucket all at once, and the spring member 7 elastically deforms and contracts, and the valve body 4a separates from the valve seat 3c to treat the wastewater, if the pressure of the wastewater that the valve body 4 receives is high enough to cause the valve body 4a in the flow path to elastically deform, the valve body 4 will elastically deform so as to separate from the valve seat 3c due to the water pressure of the wastewater, as shown in Figure 9, and the flow path of the divided wastewater where the valve body 4a separates due to the elastic deformation will expand. By expanding the flow path of the wastewater, the wastewater treatment performance of the floor drain 6 will improve, and the wastewater can be treated quickly.
When the drainage process is completed and the water pressure in the flow path decreases, the water pressure received by the valve body 4a of the check valve decreases, and the pressure is no longer strong enough to cause elastic deformation of the valve body 4a, the valve body 4a returns to its original shape, and the flow path is opened again simply because the valve body 4a is separated from the valve seat 3c due to the contraction of the spring member 7, as shown in Fig. 7. After this, when the drainage is completed, the water pressure of the drainage is released, the spring member 7 expands again, and the valve shaft 4b moves in the direction in which the valve body 4a abuts against the valve seat 3c, so that the valve body 4 returns to the position shown in Fig. 7 and the valve body 4a abuts against the valve seat 3c again, blocking the drainage flow path.

When maintenance or cleaning is required for the above-mentioned backflow check valve fitting, the backflow check valve unit 2 can be disconnected from the floor drain outlet 6 and the backflow check valve unit 2 can be removed to perform the maintenance or cleaning. After the necessary work is completed, the backflow check valve unit 2 is reconnected from the opening 1c.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be freely modified within the scope of the invention.
For example, in the above embodiment, the spring member 7 is used as an elastic body as one of the mechanisms of the check valve, but the present invention is not limited to the above embodiment, and a mechanism utilizing the attraction/repulsion of a magnet may be adopted instead of the spring member 7.
In addition, in the above embodiment, the piping P in which the check valve is used is a drainage piping for passing liquid wastewater, but the present invention is not limited to the above embodiment, and the piping P may also be a piping for passing gas.

Reference Signs List 1: Joint body 1a: Pipe body portion 1b: Storage portion 1c: Opening 2: Check valve unit 3: Check valve unit body 3a: Lid portion 3b: Cylinder portion 3c: Valve seat portion 3d: Mounting portion 3e: Water passage 4: Valve body 4a: Valve body portion 4b: Valve shaft portion 4c: Stopper member 5: Lock member 6: Floor drain port 7: Spring member P: Piping

Claims (4)

a fluid flow path;
a valve seat portion provided around the fluid flow path;
a valve body that prevents passage of a fluid from a downstream side by contacting the valve seat portion;
It consists of:
the valve body includes a valve body portion made of a substantially plate-shaped elastically deformable material in contact with the valve seat portion, and a valve stem portion extending in a direction of the flow path,
the valve stem portion is disposed in the flow path so as to be movable in the direction of the flow path,
The valve body is biased so as to abut against the valve seat portion,
an opening/closing mechanism that causes the valve body to elastically deform and separate from the valve seat due to pressure on the valve body when a fluid flows , thereby allowing fluid from an upstream side to pass through and establishing a first open state;
an expansion mechanism that, when the opening/closing mechanism is opened, causes the valve body to move in a direction in which the valve body is separated from the valve seat due to pressure applied to the valve body when a fluid flows, thereby setting the flow path to a second opening state in which the flow path is wider than the first opening state; and
A check valve comprising: 2. The check valve according to claim 1 , wherein the check valve is provided inside a joint member having a cylindrical tubular body portion. An opening is provided on a side surface of the tubular body portion,
3. The check valve according to claim 2 , wherein the check valve is configured to be detachable from the opening. 4. The check valve according to claim 1, wherein the check valve is provided at a drain outlet for draining water from a floor surface.

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