JP7526438B2 - 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 generally plate-shaped member with a lid portion on the side, a packing on the side of the lid portion, a drainage flow path in the center, a valve seat portion that abuts against the valve body portion on the drainage flow path, and a holding portion that holds and fixes the valve stem portion in the center of the flow path. The holding portion is fixed at the center of the flow path by extending two arms from the inner side of the flow path to the holding portion, and the two arms are positioned in an opposing relationship with the holding portion as the center.
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, ensuring that the flow path is blocked, preventing the wastewater from passing through the valve body and preventing the backflow of the wastewater.
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

The check valve described in Patent Document 1 as mentioned above is a check valve that is installed in drainage piping, but drainage is usually water that has been used for purposes such as cleaning. For example, drainage from a sink contains food ingredients and cooking debris, while drainage from a washbasin, bathtub, bathroom, or floor drain contains debris, hair, etc.
Here, the check valve described in Patent Document 1 has two arm portions arranged in opposing positions centered around a holding portion that is disposed at the center of the drainage flow path.
For this reason, if dust, especially soft, elongated dust such as hair or some food ingredients (hereinafter referred to as "hair, etc."), gets mixed in the wastewater, the hair or other elongated dust gets caught across the arm, and even when the wastewater flows, it does not flow down but remains there, making it unsanitary. Also, if the hair or other dust remains near the water stop point of the check valve, that is, the upstream side of the valve body and the valve seat, when the check valve is blocked, the ends of the dust such as hair get caught between the valve body and the valve seat, causing the blockage to be incomplete, and the backflowing wastewater may pass over the check valve and enter the upstream side.
The present invention has been invented in consideration of the above-mentioned problems, and provides a backflow prevention valve which has a holding portion and an arm portion which arranges the holding portion in a flow path, and which allows the debris, particularly soft, elongated debris such as hair or some food ingredients, to easily flow downstream and be disposed of even if it is mixed in the arm portion, without the debris getting caught and remaining in the arm portion.

The invention described in claim 1 is
a valve body that prevents passage of a fluid from a downstream side by contacting the valve seat;
the valve body includes a valve stem portion that extends in the upstream direction of the flow path and holds the valve body, a holding portion that holds and fixes the valve stem portion is provided within the flow path, and a single arm portion is provided to hold the valve body from the inner surface of the flow path to the holding portion ,
This is a check flow valve characterized in that the upstream surface of the arm portion is provided with a sloping portion that slopes downstream from the connection between the inner surface of the flow path and the arm portion toward the end in the opposite direction .

The present invention as set forth in claim 2 is
a fluid flow path;
A valve seat portion provided on the flow path of the fluid;
a valve body that prevents passage of a fluid from a downstream side by contacting the valve seat portion,
the valve body includes a valve stem portion that extends in the upstream direction of the flow path and holds the valve body, a holding portion that holds and fixes the valve stem portion is provided within the flow path, and two or more arms hold the valve body from an inner surface of the flow path to the holding portion,
A check valve, characterized in that all of the arm portions are provided in an area narrower than one of equal areas into which the flow passage is divided when viewed in the axial direction of the flow passage.
It is.

The present invention as defined in claim 3 is
The check valve according to claim 2, characterized in that the upstream surface of the arm portion is provided with a sloping portion that slopes downstream from the connection portion between the inner surface of the flow path and the arm portion toward the end in the opposite direction.

The present invention as set forth in claim 4 is
The check valve according to any one of claims 1 to 3, characterized in that the valve body is composed of a valve body portion made of a substantially plate-shaped elastically deformable material that abuts the valve seat portion, and the valve stem portion is provided on the valve body portion.

The present invention as set forth in claim 5 is
5. 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 set forth in claim 6 is
The backflow check valve is characterized in that the backflow check valve is provided in a drain outlet for draining the tank body or the floor surface, or in a pipe continuing from the drain outlet.

In the inventions described in claims 1 and 2, when debris, especially hair, is mixed in the wastewater, the arm portion itself is reduced, so that even if hair or other debris is mixed in the wastewater, it will not become entangled in the arm portion.
Furthermore, if the arm portion does not have any elements extending toward the upstream side, even if hair or the like becomes tangled in the arm portion, it will flow out from the end of the arm portion through drainage and can be easily discharged downstream without continuing to become tangled.
The above-mentioned effect is particularly effective in a check valve having a valve body having a valve body portion made of a substantially plate-shaped elastically deformable material that abuts against a valve seat portion, and a valve stem portion provided on the valve body, as described in claim 3.
In addition, in the present invention described in claim 4, the upstream surface of the arm portion is provided with an inclined portion that slopes downstream as it moves from the connection side of the flow path to the end in the opposite direction, making it easier for dirt, hair, etc. that has become tangled in the arm portion to flow out.
In the inventions recited in claims 5 and 6, the place or equipment in which the check valve is used can be clearly indicated.

FIG. 2 is a cross-sectional view showing the construction state of the first embodiment. FIG. 2 is a cross-sectional view showing an open state of the check valve of FIG. 1. FIG. 2 is a cross-sectional view in a planar direction of the joint member 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 an open state of the check valve unit of FIG. 7. FIG. 8 is a plan view of the check valve unit of FIG. 7 . FIG. 11 is a cross-sectional view showing the component configuration of a check valve unit according to a second embodiment. FIG. 13 is a cross-sectional view in a plan view of an embodiment in which a plurality of arm portions are provided.

A first embodiment of the present invention will be described below with reference to the drawings. The drainage pipe using the check valve 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 5, a check valve unit body 3, and a lock member 6, which will be described below.
The valve body 5 is made of an elastic material and is composed of a disk-shaped, i.e., approximately plate-shaped, valve body portion 5a and a valve stem portion 5b that is provided perpendicular to the valve body portion 5a from the center of the valve body portion 5a. The valve body 5 is generally called an umbrella valve because it has an umbrella-like shape.
The check valve unit body 3 is a generally cylindrical member with a lid 3a on the side that closes the opening 1c, and the upstream surface of the cylindrical part has an abutment surface with the storage part 1b, and this abutment surface and the side of the lid 3a are provided with packing. The cylindrical part also 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 also has a retaining part 3d at its center that has an attachment port 3f to which the valve shaft 5b is attached toward the upstream direction of the water passage 3e, and further has an arm part 4 that extends from the retaining part 3d to the inner surface of the water passage 3e.
Describing the arm portion 4 of this embodiment in detail, when viewed in the axial direction of the cylindrical flow path, as shown in FIG. 3, the arm portion 4 has a shape in which only one linear rib extends from the retaining portion 3d located at the center position of the circular shape toward the inner surface of the flow path.
That is, this embodiment is a joint member that employs a check valve having only one arm portion that holds the area from the inner surface of the flow passage to the holding portion.
As is apparent from the cross-sectional side view of the arm portion 4 shown in Figures 1, 2, etc., the arm portion 4 has an inclined portion 4a on the upstream surface of the arm portion 4 that slopes downstream from the inner surface of the flow path toward the end in the opposite direction, i.e., the holding portion 3d side.
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 6 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 5 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 is attached to the valve body 5 by inserting the valve stem 5b into the mounting port 3f of the holding part 3d from the valve seat 3c side (downstream side) and attaching the valve body 5 so that the valve body 5a abuts against the valve seat 3c. In addition, the locking member 6 is attached to the lid 3a of the check valve unit body 3 in a rotatable manner.
In this embodiment, when the pressure of a fluid, i.e., wastewater, acts on the flow path within the valve seat portion 3c from the upstream side, the valve body portion 5a of the valve body 5 elastically deforms and moves away from the valve seat portion 3c, allowing the wastewater to pass through.

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 (valve body 5 and 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 5 and 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 6 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 5 abuts against the valve seat portion 3c as shown in FIG. 1, blocking the drainage flow path.
In this drainage piping, when wastewater backflows from the downstream side, the contact between the valve body 5a and the valve seat 3c is brought closer by the application of the water pressure of the backflow water from the downstream side, and the flow path is reliably blocked, so that the wastewater cannot pass through the check valve and the backflow of the wastewater is prevented. In addition, since the valve body 5a 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 water enters the inside of the fitting body 1 from the upstream piping P and flows onto the valve body portion 5a on the water passage 3e of the check valve unit body 3. When a certain amount of drainage water accumulates on the water passage 3e of the check valve unit body 3 or inside the fitting body 1 upstream of the valve body portion 5a, the pressure of the accumulated drainage water causes the valve body portion 5a to elastically deform and move away from the valve seat portion 3c as shown in Figure 2, opening the drainage flow path, and the drainage water accumulated inside the check valve unit body 3 and the 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.
When the drainage is completed, the valve body 5a returns to the shape shown in FIG. 1 due to its own elasticity, and the valve body 5a abuts against the valve seat 3c again, thereby closing the drainage flow path.

When maintenance or cleaning is required for the coupling member using the check valve, the rotation lock between the lock member 6 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 lock member 6 and opening 1c can be connected by the rotation lock, allowing the drainage piping to be used without hindrance.

If dust, especially hair, is mixed in the drainage water and the hair gets caught straddling the arm portion 4, the dust and hair will flow downstream along the inclined portion 4a as the drainage flows from upstream to downstream, and will not flow out of the end of the holding portion 3d into the flow path and remain on the arm portion 4. This eliminates problems such as dust and hair remaining there and becoming unsanitary, or hair getting caught between the valve body and the valve seat during blockage, causing an incomplete blockage.

In addition, the drain joint using the check valve of the first embodiment may be used with the flow path arranged horizontally instead of vertically. In this case, if the arm portion 4 is arranged above the center of the flow path as viewed in the axial direction, even if hair or the like gets caught in the arm portion 4, it will fall from the end of the arm portion 4 and flow downstream.
Furthermore, when viewed in the axial direction of the flow path, the arm portion 4 is positioned below the center, and if a hair or other object becomes caught across the arm portion 4, the dust or hair will flow down along the inclined portion 4a of the arm portion 4 each time drainage occurs, moving toward the end of the arm portion 4 and then flowing downstream from the end of the arm portion 4.
As a result, no matter what direction the arm portion 4 is positioned in, if a hair or the like gets caught across the arm portion 4, the dust, hair, etc. will not remain on the arm portion 4 but will be discharged downstream.

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 7, a check valve unit 2, and a piping P under the floor, which will be described below.
The floor drain 7 is an opening provided on a floor surface where washing water and the like are frequently discharged onto the floor surface due to use and cleaning of a toilet room, etc., and is configured so that the check valve unit 2 can be detachably connected inside it.
As shown in Figure 6, the underfloor piping P is a drainage piping installed in the underfloor space of the floor surface where the floor drain outlet 7 is provided, 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 7.
The check valve unit 2 is composed of a valve body 5 and a check valve unit body 3, which will be described below.
The valve body 5 is composed of a disk-shaped valve body 5a made of an elastic material and a valve stem 5b that is provided perpendicular to the valve body 5a from the center of the valve body 5a. The valve body 5 is shaped like an umbrella, and is generally called an umbrella valve.
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.
In addition, the valve seat portion 3c is provided at its center with a retaining portion 3d having an attachment port 3f to which the valve shaft portion 5b is attached toward the upstream direction of the water passage 3e, and an arm portion 4 is further provided extending from the retaining portion 3d to the inner surface of the water passage 3e.
Describing the arm portion 4 of this embodiment in detail, when viewed in the axial direction of the cylindrical flow path, as shown in FIG. 9, the arm portion 4 has a shape in which a single arm consisting of a sector-shaped portion extending at an angle of approximately 90 degrees from the holding portion 3d located at the center position of the circular shape toward the inner surface of the flow path.
That is, this embodiment is a drain pipe that employs a check valve having only one arm portion that holds the area from the inner surface of the flow passage to the holding portion.
As is apparent from the cross-sectional side view of the arm portion 4 shown in Figures 7 and 8, the arm portion 4 has an inclined portion 4a on the upstream surface of the arm portion 4 that slopes downstream from the inner surface of the flow path toward the end in the opposite direction, i.e., the holding portion 3d side.
When in use, the check valve unit 2 connected to the floor drain 7 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 7.

In the floor surface and its drainage piping configured as described above, when there is no drainage, as shown in Figure 6 or Figure 7, the valve body 5 in the floor drain port 7 abuts against the valve seat portion 3c, blocking the drainage flow path.
When wastewater backs up from the downstream side of the underfloor piping P, the valve body 5a 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 5a 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 wastewater is discharged onto the floor surface for reasons such as cleaning, the wastewater flows from above the floor surface into the floor drain port 7. When wastewater is discharged into the floor drain port 7 in this manner, the wastewater flows onto the valve body portion 5a on the water passage 3e of the check valve unit main body 3. When a certain amount of wastewater accumulates in the water passage 3a upstream of the valve main body 5, the pressure of the accumulated wastewater causes the valve body portion 5a to elastically deform in the direction away from the valve seat portion 3c as shown in Figure 8, opening the flow path for the wastewater, and the wastewater accumulated inside the check valve unit main body 3 and the joint main body 1 flows out, passes through the water passage 3e of the check valve unit main body 3, and is discharged into the downstream piping P.
When the drainage is completed, the water pressure of the drainage is released, the valve body 5a returns to its original shape due to its elasticity, and the valve body 5a abuts against the valve seat 3c again, thereby closing the drainage flow path.

When maintenance or cleaning is required for the drainage piping that employs the above-mentioned backflow check valve, the backflow check valve unit 2 can be disconnected from the floor drain outlet 7 and removed to perform the maintenance or cleaning. After the necessary work is completed, the backflow check valve unit 2 is reconnected from the floor drain outlet 7.

If dust, especially hair, is mixed in the drainage water and the hair gets caught straddling the arm portion 4, the dust and hair will flow downstream along the inclined portion 4a as the drainage flows from upstream to downstream, and will not flow out of the end of the holding portion 3d into the flow path and remain on the arm portion 4. This eliminates problems such as dust and hair remaining there and becoming unsanitary, or hair getting caught between the valve body and the valve seat during blockage, causing an incomplete blockage.

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 backflow check valve is applied to a drain joint in the piping, and to a floor drain and its drain piping, but the present invention is not limited to the above embodiment, and the backflow check valve may be applied to a drain provided on the bottom of a tank body. The tank body may be a sink, a wash basin, or a waterproof pan in a bathroom. The backflow check valve is not limited to liquids, and may be applied to piping for gas, which is a fluid.

In the above embodiment, the arm portion that holds the inner surface of the flow path from the holding portion is configured with only one, but the present invention is not limited to the above embodiment, and a plurality of arm portions (two in the embodiment of FIG. 11) may be arranged in a range narrower than one of the equal regions of the flow path when viewed in the axial direction of the flow path, particularly preferably in one of the four equal regions of the flow path as shown in FIG. 11. Even in this case, if hair or the like gets caught across the multiple arm portions 4, it will not flow out from the end of the holding portion 3d into the flow path and remain on the arm portion 4. Therefore, as in the case of a single arm portion 4, problems such as dust, hair, etc. remaining and becoming unsanitary, and hair, etc. being caught between the valve body portion and the valve seat portion during blockage and causing incomplete blockage can be eliminated.
However, if multiple arm portions 4 are arranged in opposing positions, it will be impossible for dust, hair, etc. to flow down from the ends of the arm portions 4. Therefore, in order to achieve the function of the present invention, it is necessary to configure the multiple arm portions 4 to be arranged in a range narrower than one of the equal areas of the flow path when viewed in the axial direction of the flow path, and particularly preferably within one of the areas of the flow path divided into four equal parts.

In addition, in the above embodiment, the inclined portion 4a is formed continuously from the inner surface of the flow path to the retaining portion 3d, but the present invention is not limited to the above embodiment. Even if a step that is not inclined with respect to the flow path is provided in the middle of the inclined portion 4a, dust, hair, etc. can be discharged downstream without hindrance as long as the inclined portion 4a does not have a reverse gradient.

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: Holding portion 3e: Water passage 3f: Mounting port 4: Arm portion 4a: Inclined portion 5: Valve body 5a: Valve body portion 5b: Valve stem portion 6: Locking member 7: Floor drain port P: Piping

Claims (6)

a fluid flow path;
A valve seat portion provided on the flow path of the fluid;
a valve body that prevents passage of a fluid from a downstream side by contacting the valve seat portion,
The valve body includes a valve stem portion that holds the valve body and extends in an upstream direction of the flow path.
A holding portion for holding and fixing the valve stem portion is provided in the flow path,
The arm portion that holds the inner surface of the flow channel to the holding portion is configured as only one ,
A check flow valve characterized in that the upstream surface of the arm portion is provided with a sloped portion that slopes downstream from the connection between the inner surface of the flow path and the arm portion toward the end in the opposite direction . a fluid flow path;
A valve seat portion provided on the flow path of the fluid;
a valve body that prevents passage of a fluid from a downstream side by contacting the valve seat portion,
The valve body includes a valve stem portion that holds the valve body and extends in an upstream direction of the flow path.
A holding portion for holding and fixing the valve stem portion is provided in the flow path,
The flow channel is supported by two or more arm portions from the inner surface to the support portion,
A check valve, characterized in that all of the arm portions are provided in an area narrower than one of equal areas into which the flow passage is divided when viewed in the axial direction of the flow passage. In the check valve,
3. The check valve according to claim 2, wherein the upstream surface of the arm portion is provided with an inclined portion that slopes toward the downstream side from the connection portion between the inner surface of the flow path and the arm portion toward the end in the opposite direction. In the check valve,
4. The check valve according to claim 1, wherein the valve body is composed of a valve body portion made of a substantially plate-shaped elastically deformable material that abuts against the valve seat portion, and the valve stem portion is provided on the valve body portion. 5. The check valve according to claim 1, wherein the check valve is provided inside a joint member having a cylindrical tubular body portion. The check valve according to any one of claims 1 to 4, characterized in that the check valve is provided in a drain outlet for draining water from the tank body or the floor surface, or on a pipe continuing from the drain outlet.

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