JP2023142454A - Leakage detection mechanism - Google Patents

Abstract

To provide a leakage detection mechanism that can detect even a small amount of leakage from a valve or a joint where leakage to the outside hardly occurs.SOLUTION: The present invention relates to a leakage detection mechanism 1 for detecting an inside leakage of a fluid apparatus R including: an inside space 2 in which a fluid circulates; and a sealed space 3 in which a first seal member S1 is arranged between the sealed space and the inside space 2 so that there is no leakage of fluid from the inside space 2. The leakage detection mechanism includes: a leak port 4 for connecting the sealed space 3 and the outside to each other; a cylindrical cock 10 for being removably attached to an outside opening end 40 of the leak port 4; a transparent or translucent tube 11 fixed to a hollow part 10a of the cock 10; and an amount of liquid L that does not move by its own weight due to the viscosity according to the diameter of tube in the tube 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a leak detection mechanism that detects internal fluid leaking from a leak port provided in a valve or a joint.

In a typical valve, a valve chamber in which a valve body abuts and separates from a valve seat is communicated with an inflow path and an outflow path. The valve body is connected via a stem to an actuator that operates the valve body, and a sealing member is provided to prevent fluid from leaking outside from the space through which the stem communicates with the external actuator from the valve chamber, which is an internal space. has been done. In the case of a valve that handles high-pressure fluids, such as hydrogen, it is necessary to retighten the sealing member, but when retightening, first loosen the fastening means such as bolts that tighten the sealing member, and make sure that the sealing member is in place. A so-called pressure release is performed in which the sealing member is moved to a leak port formed in the closed space provided, and the pressure in the internal space is released to the outside (for example, Patent Document 1).

The leak port provided in such a high-pressure valve is used not only for releasing pressure from the internal space when retightening the seat member, but also as a port for detecting leakage of fluid from the internal space.

In the case of a joint that connects pipes, a sealing member such as a gasket is provided between the end faces of the pipes, and an annular bolt and nut are used as fastening members to connect the pipes. In this case, a pipe joint has been proposed in which a leak port is formed in a male-threaded annular bolt that is a fastening member to check for leakage from piping (for example, Patent Document 2).

International Publication No. 2021/220963 Japanese Patent Application Publication No. 2021-143762

In order to detect leaks from leak ports of valves and joints described in Patent Documents 1 and 2, a detection device is used depending on the fluid flowing through the internal space.

However, when measuring fluid leakage using such a general detection device, it is difficult to detect a small amount of leakage from a valve or a joint, which usually causes almost no leakage to the outside. Further, preparing a detection device suitable for an expensive fluid would increase costs, and therefore, a leak detection mechanism that is easy to use is desired in the market.

The present invention has been made in view of the above points, and its main object is to provide a leak detection mechanism that can detect minute leaks from valves and joints with almost no leakage to the outside.

A leak detection mechanism according to an embodiment of the present invention includes:
an internal space through which fluid circulates;
a sealed space in which a first sealing member is disposed between the inner space and the inner space to prevent the fluid from leaking;
A leak detection mechanism for detecting an internal leak of a fluid device having
a leak port that communicates the sealed space with the outside;
a cylindrical cock that is removably attached to the external open end of the leak port;
a transparent or translucent tube that fits into the hollow part of the cock;
The tube consists of an amount of liquid that does not move due to its own weight depending on the tube diameter due to its viscosity.

The inside of the leak port and the inside of the tube attached to the cock form a communication space that communicates with each other, and the liquid that does not move under its own weight increases the pressure in the communication space when there is a leak from the internal space in the leak port. Leakage is detected by the movement of liquid. The conditions under which the liquid does not move due to its own weight are:
M×g<πR×γ×cosθ
M: droplet mass, g: gravitational acceleration, R: tube diameter, γ: surface tension, θ: liquid contact angle.It is a fluid with droplet mass M and surface tension γ.

In the above configuration, the tube can have a vertical portion aligned with the position where the leak port is formed.

Furthermore, in these cases, a second sealing member can be provided between the closed space and the outside.

According to the leak detection mechanism of the embodiment of the present invention, by simply attaching a cylindrical cock with a tube attached tightly to the external open end of the leak port, if there is a leak from the inside, the liquid in the tube will meet the law. Regardless of the type of fluid flowing in the internal space, leaks can be easily detected.
be able to.

1 shows a leak detection mechanism according to an embodiment of the present invention, in which (a) is a partially cutaway front view, and (b) is a cross-sectional view taken along line XX in (a). The leak detection mechanism is shown in which (a) shows that the cock of the leak detection mechanism has a tapered truncated conical shape, and the circumferential surface inside the external open end of the leak port has a truncated conical shape that matches the inclination of the cock; An example is shown in which the cock of the detection mechanism has a tapered truncated conical shape and the circumferential surface inside the external open end of the leak port is cylindrical. The leak detection mechanism is shown attached to a valve as a fluid control device, with (a) being a front sectional view and (b) being an enlarged view of the part to which the leak detection mechanism is attached. FIG. 3 is a front sectional view showing a state in which the leak detection mechanism is attached to a joint as a fluid control device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the embodiments described below.

<Embodiment 1>
FIG. 1 shows a leak detection mechanism 1 according to a first embodiment. This leak detection mechanism 1 is shown as an example attached to a valve 5 as a fluid control device.

The leak detection mechanism 1 of the present embodiment includes an internal space 2 through which fluid flows, and a sealed space 3 in which a first seal member S1 is disposed between the internal space 2 and the internal space 2 so that the fluid does not leak from the internal space 2. The device detects internal leakage of a valve 5 as a fluid device R having a leak port 4 that communicates the closed space 3 with the outside, and a cylindrical cock 10 that is detachably attached to an external open end 40 of the leak port 4. It consists of a transparent or translucent tube 11 that fits into the hollow part 10a of the cock 10, and an amount of liquid L that does not move due to its own weight within the tube 11 depending on the tube diameter due to its viscosity. In addition, the second sealing member S2 disposed between the sealed space 3 and the outside reliably blocks communication between the sealed space 3 and the outside and prevents leakage when the leakage from the internal space 2 is extremely small. This serves to reliably guide the fluid to the leak port 4.

The fluid device R shown in FIGS. 1 to 3 is a valve 5, and although the type of valve is not particularly limited, it is a needle valve in this embodiment. The valve 5 is used, for example, as an on-off valve for high-pressure hydrogen, and the body 50 includes an internal space 2 serving as a valve chamber, an upstream flow path 20 communicating with this internal space 2, a downstream flow path 21, and an upstream flow path 21. An inflow port 20A is provided at the open end of the side flow path 20, an outflow port 21A is provided at the open end of the downstream flow path 21, and a stem 53 is provided with a valve body at its tip that abuts and separates from a valve seat 51 formed in the internal space 2. A closed space 3 to be inserted is formed.

Inside the internal space 2, when fluid is supplied from the inflow port 20A and discharged from the outflow port 1A, a first seal member S1 and a first seal member S1 are provided to prevent the fluid from leaking outside from the closed space through which the stem 53 is inserted. A second seal member S2 is provided. The first seal member S1 and the second seal member S2 are not particularly limited in shape, material, etc., as long as they have a structure that fills the gap between the outer peripheral surface of the stem 53 and the inner peripheral surface of the sealed space 3. Flexible sealing materials, gaskets, O-rings, etc. are fitted into the shaft portions of the plurality of stems 53 to suppress external leakage of fluid.

and. In the valve 5 in this embodiment, the sealing member, particularly the first sealing member S1, is retightened periodically from the viewpoint of preventing fluid leakage to the outside. When retightening, the fastening means 54 that tightens the first seal member S1 and the second seal member S2 is loosened, and the leak port 4 formed in the sealed space 3 where the first seal member S1 and the second seal member S2 are disposed is removed. The first seal member S1 is moved until the pressure in the internal space 2 is released to the outside, so-called pressure relief.

The leak port 4 is used for the above-mentioned pressure relief in the valve 5 of this embodiment, and a mounting structure 41 is formed to attach the cock 10 of the leak detection mechanism 1 to the external open end 40 of the leak port 4. do. This mounting structure 41 is configured such that, for example, a female thread is formed on the circumferential surface of the leak port 4 near the external open end 40, and a male thread formed on the outer circumferential surface of the cock 10 is screwed together so that it can be easily attached and removed. can do.

Further, as shown in FIG. 2(a), the circumferential surface of the leak port 4 near the external open end 40 is made into a conical inclined surface 41A, and the circumferential surface of the cock 10 is also made into a truncated conical shape with the same inclination angle. , it can also be constructed so that it can be easily inserted and removed. Furthermore, as shown in FIG. 2(b), the circumferential surface of the cock 10 may be shaped like a truncated cone, and the circumferential surface of the leak port 4 near the external open end 40 may be shaped like a columnar shape 41B with no slope. The cock 10 of the leak detection mechanism 1 shown in FIG. 2 is preferably made of an elastic member. However, although the material of the cock 10 shown in FIG. From the viewpoint of not creating a gap between the inclined surface 41A and the circumferential surface of the cock 10 so that the fluid flows smoothly, it is preferable to use an elastic member as the material of the cock 10. Note that the position of the liquid L in the tube 11 in FIG. 2(b) shows a state where there is a small amount of leakage from the internal space 2 and the position has risen from the steady state in FIG. 2(a).

The material of the transparent or translucent tube 11 fitted into the hollow part 10a of the cock 10 is not particularly limited, but for example, soft polyvinyl chloride or the like is used. An appropriate amount of liquid L is put into this tube 11. The liquid L is injected in an amount that becomes a part of the vertical portion 12 of the tube 11 when visually observed from the outside, and is set in an amount that does not move under its own weight. The amount that does not move due to its own weight is calculated by the droplet mass of the liquid, and where M: droplet mass, g: gravitational acceleration, R: tube diameter, γ: surface tension, and θ: contact angle of the liquid, the following formula (1) is used. If the liquid has a droplet mass that satisfies the following, the liquid L will not move (fall) due to its own weight.
M×g<πR×γ×cosθ...(1)

The liquid L injected into the tube 11 is preferably colored red or blue so that it can be easily visually observed from the outside.

Further, it is preferable that the tube 11 is formed with a vertical portion 12 that matches the formation position of the leak port 4. For example, when the external open end 40 of the leak port 4 is on the side, the tube 11 is bent into an L shape. , forming the vertical portion 12. When the external open end 40 is on the top surface, the tube 11 can be used without being bent. By providing the vertical portion 12 and injecting the liquid L into the vertical portion 12, when a leak occurs, the movement of the liquid L will be from the bottom to the top, making visual inspection easier. Furthermore, after the liquid L is injected, markings are applied to the surface of the tube 11 to match the upper surface of the liquid L, so that movement of the liquid L (occurrence of internal leakage) can be easily observed visually.

In this way, the leak detection mechanism 1 of the present embodiment can be easily attached to and detached from the external open end 40 of the leak port 4, so that it can be used easily when the equipment is in operation or when the fluid starts flowing after retightening the seal member. Also, fluid leakage can be easily confirmed visually during periodic inspections. Furthermore, in a site where a plurality of fluid devices R are installed, if one leak detection mechanism 1 is prepared, all the devices can be tested for leaks.

<Embodiment 2>
FIG. 4 shows a leak detection mechanism 1 according to the first embodiment. This leak detection mechanism 1 is shown as an example attached to a joint 6 as a fluid control device.

The joint 6 to which the leak detection mechanism 1 of this embodiment is attached connects the end faces of the first pipe 60A and the second pipe 60B to prevent leakage from the internal space 2 through which fluid flows into the sealed space 3 between the end faces. A first sealing member S1 is provided, and an annular bolt 61 is fitted to the first pipe 60A and an annular nut 62 is fitted to the second pipe 60B as a fastening member. Then, the bolt 61 and the nut 62 are screwed together, and the first seal member S1 between both end faces is deformed under pressure to connect the pipe 60.

In this embodiment, the second seal member S2 is provided at the tip and rear end of the annular bolt 61 of the fastening member, so that only the leak port 4 communicates between the sealed space 3 and the outside.

The structure of the leak detection mechanism 1 attached to the open end 40 of the leak port 4 includes a cock 10 and a tube 11 fitted into a hollow portion 10a of the cock 10. The other configurations are the same as those in the first embodiment, and their explanation will be omitted.

Since the leak detection mechanism according to the embodiment of the present invention can easily perform a leak test on site, it can be suitably used for internal leak tests of various fluid devices equipped with a leak port.

1 Leak detection mechanism 10 Cock 10a Hollow part 11 Tube 2 Internal space 3 Sealed space 4 Leak port 40 External open end 5 Valve (fluid equipment)
6 Fittings (fluid equipment)
L Liquid S1 First seal member S2 Second seal member

Claims (3)

an internal space through which fluid circulates;
a sealed space in which a first sealing member is disposed between the inner space and the inner space to prevent the fluid from leaking from the inner space;
A leak detection mechanism for detecting an internal leak of a fluid device having
a leak port that communicates the sealed space with the outside;
a cylindrical cock that is removably attached to the external open end of the leak port;
a transparent or translucent tube that fits into the hollow part of the cock;
A leak detection mechanism consisting of an amount of liquid within the tube that does not move due to its own weight depending on the tube diameter due to its viscosity. 2. The leak detection mechanism according to claim 1, wherein the tube has a vertical portion that corresponds to a position where the leak port is formed. 3. The leak detection mechanism according to claim 1, further comprising a second seal member disposed between the sealed space and the outside.

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