JP2001187975A - Emergency shutoff valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emergency shutoff valve capable of specifying and easily confirming the position of a flow sensor and also easily confirming that the passing water flow is above a set value when the flow sensor starts to rotate and the flow velocity of the passing water flow when the flow sensor is in the other position. SOLUTION: A sensor shaft 18 constituting an operating mechanism 60 is provided with a flow velocity display device 80. The flow velocity display device 80 comprises a rotation amplifying mechanism 85 for amplifying and taking out the rotation of the sensor shaft 13, a pointer 81 fixed to the output shaft 85b of the rotation amplifying mechanism 85, and a circular scale plate 82 having a flow velocity display scale 83 conformed to the tip 81A of the pointer 81. The flow velocity display scale 83 capable of confirming the flow velocity of the passing water flow F is provided on the scale plate 82.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emergency shutoff valve for urgently shutting off a water pipe when an earthquake occurs, for example.

[0002]

2. Description of the Related Art Conventionally, a self-powered emergency shutoff valve having a function of shutting off water flow by itself in the event of an abnormal situation in which a water distribution pipe is damaged by an earthquake is known as shown in FIG. . In this figure, reference numeral 1 denotes a valve box, 2 denotes a valve body, and 3 denotes a valve rod.
A and 4B are connected, and when the valve body 2 is opened as shown in the figure, as shown by an arrow F, the water pipe 4A is connected to the water pipe 4B.
Water passes in the direction of. On the other hand, the valve body 2 fixed to the valve rod 3 rotates together with the valve rod 3 by about 90 degrees around its axis, whereby a closed state of the flow path can be obtained. This type of emergency shut-off valve includes a flow velocity detection mechanism 10, an engagement / disengagement mechanism 20, a rotation mechanism 30, a torque generation source 40, and a link mechanism 50. The rotation mechanism 30 and the link mechanism 50 constitute a linking mechanism 70.

The flow velocity detecting mechanism 10 is configured to detect the flow velocity of the passing water flow F and operate in a region where the flow velocity is equal to or higher than a set value. That is, as shown in FIGS. 7 to 10, a flow sensor 11 protruding into the valve box 1 and a sensor horizontally and rotatably supported in a hood 12 mounted on the valve box 1 in a watertight manner. A sensor lever 14 fixed to the end of the sensor shaft 13 outside the shaft 13 and the hood 12,
A balance weight 15 is fixed to one end of a fulcrum 14A of the sensor lever 14, and a sensor weight 16 is provided on the opposite side of the balance weight 15 of the sensor lever 14 so as to be slidable and positionable in the direction of the arrow. The upper end of the flow sensor 11 is fixed to the sensor shaft 13.

As shown in FIGS. 7 to 10, the engagement / disengagement mechanism 20 includes a vertical round rod-shaped rod 21 and a bell-crank-shaped latch lever 22 connected to the lower end of the rod 21 and interlocking therewith. ing. The upper end of the rod 21
The sensor lever 14 is swingably connected via a pin 23 to the opposite side of the balance weight 15 of the sensor lever 14, and the lower end of the sensor lever 14 is connected to the distal end of the one-side extension 22 </ b> A of the latch lever 22. The latch lever 22 is rotatably supported by the pin 22B, and is provided with an engaging claw 22d at the distal end of the other side extension 22D.

The operating mechanism 60 is constituted by the sensor shaft 13 and the sensor lever 14 which are a part of the flow velocity detecting mechanism 10, and the engaging / disengaging mechanism 20.

As shown in FIGS. 7, 8, 11, 12, and 13, the rotating mechanism 30 includes a latch 31, a weight 32, and a striker 33. The latch 31 is fixed to one end of a shaft 34, and the shaft 34 is horizontally and rotatably supported by bearings 6, 6 provided on an upper portion of the cylinder base 5. Thus, when the latch 31 rotates together with the shaft 34, the tip claw 31A has an indentation rotation locus R
Above, it corresponds to the engaging claw 22d of the latch lever 22 so that it can be disengaged. The weight 32 is fixed to the other end of the shaft 34 via a lever 35 extending obliquely upward. The striker 33 includes a pair of left and right arm portions 33A, 33A extending diagonally downward and facing each other, and a horizontal striking pin 33B bridging and connecting the lower ends of the arm portions 33A, 33A. The upper ends of the arm portions 33A, 33A are fixed to the shaft 34 between the bearings 6, 6.

[0007] As shown in FIG.
An arm 41 fixed to the valve stem 3 and a weight 42 attached to the arm 41 are provided.

The link mechanism 50 is shown in FIGS. 7, 11, and 13.
As shown in FIG. 14, a first link 51, a second link 52, and a lever 53 are provided. The distal end of the first link 51 is rotatably supported by a fixing member 55 via a horizontal pin 54, and the rear end is articulated to the distal end of the second link 52 via a horizontal pin 56. The rear end of the second link 52 is rotatably connected to the upper end of the lever 53 via a horizontal pin 57. In addition, a positioning member 58 made of a bolt and a nut is attached so as to penetrate the first link 51 in the vertical direction,
When the lower end of the positioning member 58 comes into contact with the stopper 58A, the design point C1 of the link mechanism 50 (FIG.
(See below) is regulated within limits. The lever 53 is fixed to the other end of the valve stem 3, and the lower end of the lever 53 is connected to the distal end of a piston rod 7A of the hydraulic cylinder 7 via a horizontal pin 59. Further, a projection 53A is protruded from the lower end of the lever 53, and an opening pointer 53B is provided behind the projection 53A. The hydraulic cylinder 7 is connected to a cylinder base via a horizontal trunnion 8 as shown in FIG.
The base 5 and a trunnion cover 5A that removably closes one side opening of the cylinder base 5 are swingably supported. In FIG. 8, reference numeral 17 denotes an upper stopper, and reference numeral 18 denotes a lower stopper, each of which is provided in the vicinity of the balance weight 15 in the sensor lever 14. In FIG. 11, 9A and 9B are limit switches, 9C is an opening scale plate, and 9D is a stopper. Limit switches 9A and 9B are provided when the lever 53 rotates together with the valve rod 3 when the lever 53A rotates. The opening scale plate 9C is provided corresponding to the rotation locus R, and the opening scale plate 9C is provided corresponding to the opening indicator 53B.

The linking mechanism 70 includes the rotating mechanism 30 and the link mechanism 50.

In the emergency shut-off valve having the above-described structure, when the flow velocity of the passing water flow F shown in FIG. 8 is less than the set value, the balance weight 15 and the sensor weight 16 of the flow velocity detection mechanism 10 are used.
Due to the weight ratio and the lever ratio, the sensor lever 14 is held in the downwardly-rightward position shown by the solid line in contact with the upper stopper 17, and the flow sensor 11 is at the position shown by the solid line. Therefore, the latch lever 22 of the engagement / disengagement mechanism 20 is also held at the first position shown by the solid line, and its engagement claw 22d engages with the claw 31A of the latch 31 of the rotating mechanism 30, and FIG.
Is held in a substantially horizontal posture when the valve is opened. That is, in the region where the flow rate of the passing water flow F is less than the set value, the operating mechanism 60 stops, and the engaging claw 22d of the disengagement mechanism 20 in the stopped operating mechanism 60 engages with the claw of the rotating mechanism 30 in the linking mechanism 70. The torque generating source 4 is engaged with the
Rotation of the valve stem 3 and the valve body 2 in the valve closing direction due to zero weight torque is prevented, and the valve body 2 is kept in the fully open position.

When the downstream pipe 4B of the emergency shutoff valve is damaged due to the occurrence of an earthquake or the like and the flow rate of the passing water flow F shown in FIG. 8 exceeds a set value, the flow sensor 11 rotates to the position indicated by the phantom line. However, the sensor lever 14 is held in an upwardly right position in contact with the lower stopper 18 as indicated by a virtual line. As a result, the rod 21 of the engagement / disengagement mechanism 20 is pulled up, and the latch lever 22 is rotated clockwise to the second position indicated by the imaginary line, and the engagement claw 22d is moved to the claw portion 31A of the latch 31 in the rotation mechanism 30. Evacuate from. When the engagement between the engaging claw 22d of the latch lever 22 and the claw portion 31A of the latch 31 is released, the lever is moved by the weight of the weight 32 of the rotating mechanism 30 held at the position shown by the solid line in FIG. The −35 and the shaft 34 rotate to the position indicated by the imaginary line, and the striker 33 in FIG. 11 also rotates from the position indicated by the dashed line to the position indicated by the imaginary line.

1 by the rotation of the striker 33.
The striking pin 33B shown in FIG. 3 collides with the lower surface of the joint portion between the rear end portion of the first link 51 and the front end portion of the second link 52 in the link mechanism 50 and pushes upward to bend the link mechanism 50, thereby bending the pin mechanism. 56 moves to the upper side (the other side) beyond the thought point C1 of the link mechanism 50. At that moment, the lever 41 and the valve rod 3 are rotated in the direction of the arrow R1 by the own weight torque of the weight 42 in the torque generating source 40 in FIG. 7, and the valve body 2 is rotated in the valve closing direction. Valve 2
Starts rotating in the valve closing direction, the dynamic pressure of the passing water flow F is applied to the valve body 2, and hydraulic torque in the valve closing direction is generated. On the other hand, in a state before the lever 53 is rotated by the weight torque of the weight 42, that is, in a position shown by a solid line in FIG. 11, and when the projection 53A is in contact with the limit switch 9A, the hydraulic cylinder 7 The high-pressure oil in the front chamber is returned to an oil tank (not shown) through a return passage (not shown). Therefore, by the rotation of the lever 53, the piston rod 7A of the hydraulic cylinder 7 moves forward, and the hydraulic cylinder 7 tilts upward (forward) in FIG. 11 around the trunnion shaft 8 in FIG. I do.
By operating the hydraulic cylinder 7 as described above, the valve closing speed of the valve body 2 in FIG. 7 is adjusted by the weight torque of the weight 42 and the hydraulic torque caused by the dynamic pressure of the passing water flow F, and
While preventing the occurrence of the tahammer phenomenon, the valve body 2 is closed in a substantially vertical posture to shut off the flow of water from the upstream water distribution pipe 4A to the downstream water distribution pipe 4B. This valve-closed state is maintained by rotating the lever 53 together with the valve stem 3 from the position shown by the solid line in FIG. 13 to the position shown by the imaginary line abutting on the stopper 9D and stopping. When the lever 53 rotates to the position shown by the imaginary line in contact with the stopper 9D and stops, the protrusion 53A is moved to the limit switch 9B.
The high-pressure oil in the rear chamber of the hydraulic cylinder 7 is returned to an oil tank (not shown) through a return passage (not shown). That is, in the region where the flow rate of the passing water flow F is equal to or higher than the set value, the operating mechanism 60 operates, and the operating mechanism 60
The engagement between the engaging claw 22d of the engagement / disengagement mechanism 20 and the claw 31A of the rotating mechanism 30 in the linking mechanism 70 is released, and the valve stem 3 and the valve body 2 are driven by the torque of the torque generating source 40 by its own weight.
Is allowed to rotate in the valve closing direction.

As described above, in this type of emergency shutoff valve, it is possible to shut off water flow by itself in an emergency when the water distribution pipe 4B is damaged by an earthquake.

[0014]

However, in the conventional emergency shut-off valve, when the flow rate of the passing water flow F exceeds a set value, the flow sensor 11 is indicated by a virtual line from a starting end position indicated by a solid line in FIG. Even when the flow sensor 11 is rotated toward the end position, the flow sensor 11 is largely mounted inside the hood 12,
Since the front end detection unit 11A faces the inside of the valve box 1, it is impossible to directly confirm it by visual observation. On the other hand, since the operation mechanism 60 operates in conjunction with the rotation of the flow sensor 11, it is not impossible to indirectly confirm the rotation of the flow sensor 11 by visually observing the operation of the operation mechanism 60. . However, the operation mechanism 60 is a flow sensor 1
1 does not have a rotation display function,
Although it can be confirmed that 1 is at the two positions of the start end position and the end position, it is impossible to specify and confirm which position is between the start end position and the end position. Further, the passing water flow F when the flow sensor 11 starts rotating is equal to or larger than a set value, and the flow velocity of the passing water flow F when the flow sensor 11 is at an intermediate position between the start end position and the end position. The flow rate of the passing water flow F just before the sensor 11 is rotated to the vicinity of the end position and the emergency shut-off valve is shut off, and the flow water flow when the emergency shut-off valve is shut off when the flow sensor 11 is turned to the end position. The flow rate of F cannot be confirmed. Therefore, when the flow rate of the passing water flow F becomes equal to or higher than the set value, it cannot be accurately determined whether or not the emergency shutoff valve is shut off.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to be used when the flow sensor is at an arbitrary position between the start position and the end position or between the start position and the end position. These positions can be specified and easily confirmed, and the passing water flow F when the flow sensor 11 starts rotating is equal to or larger than a set value, and the flow sensor 11 is positioned at the start end position and the end position. , The flow rate of the passing water flow F when the flow sensor 11 is rotated to near the end position and the flow rate of the passing water flow F immediately before the emergency shutoff valve is shut off, and the flow sensor 11 reaches the end position. It is an object of the present invention to provide an emergency shut-off valve which can easily confirm the flow rate of the passing water flow F when the emergency shut-off valve is rotated and shut off.

[0016]

In order to achieve the above object, an emergency shut-off valve according to the present invention comprises: a cylindrical valve box 1 having both axial ends opened; A valve stem 3 having an intersecting axis and rotatably supported about the axis; and a valve stem 3 fixed to the valve stem 3 and rotating around the axis inside the valve box 1 simultaneously with the valve stem 3. Valve box 1
A valve body 2 for permitting or shutting off water flow inside the valve body; and a valve body 2 fixedly attached to an outlet of the valve stem 3 outside the valve box, and constantly urges the valve body 2 through the valve rod 3 to the own weight torque in the valve closing direction. Torque source 40
A flow sensor 11 that detects the flow rate of the passing water flow F inside the valve box and rotates in a region where the flow rate of the passing water flow F is greater than or equal to a set value; and a valve box that follows the rotation of the flow sensor 11 1 and an operating mechanism 60 operating outside the
When the operation mechanism 60 is stopped when the flow rate of the passing water flow F is less than a set value and the operation mechanism 60 is stopped, the torque generation source 40 The valve rod 3 and the valve body 2 are prevented from rotating in the valve closing direction by their own weight torque to maintain the valve element 2 in a fully open position, and the engagement with the operation mechanism 60 is released by the operation of the operation mechanism 60. And an interlocking mechanism 70 that allows the torque generating source 40 to rotate the valve stem 3 and the valve body 2 in the valve closing direction by their own weight torque. And a scale plate 82 corresponding to the pointer 81, and the scale plate 82 of the flow rate display device 80 is provided.
Is provided with a flow velocity display scale 83 at least capable of confirming the flow velocity of the passing water flow F.

According to the present invention, when the flow rate of the passing water flow F exceeds the set value and the flow sensor 11 starts to rotate, the operation mechanism 60 operates following the rotation of the flow sensor 11 and operates. With the operation of the mechanism 60, the pointer 81 operates. A flow rate display scale 83 that can confirm at least the flow rate of the passing water flow F is provided on a scale plate 82 of the flow rate display device 80. By reading the corresponding flow rate display scale 83 with the pointer 81, the flow sensor 11 starts. It is possible to easily identify and confirm the position between the start position and the end position as well as the position between the start position and the end position, and the flow sensor 11 starts rotating. The flow rate of the passing water flow F when the flow sensor F is at or above the set value, the flow rate of the passing water flow F when the flow sensor 11 is at an intermediate position between the start position and the end position, and the flow sensor 11 rotates to near the end position. The flow rate of the passing water flow F immediately before the emergency shutoff valve is shut off and the flow rate of the passing water flow F when the emergency shutoff valve is shut off by rotating the flow sensor 11 to the end position can be easily checked. Can

[0018]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a main part of an emergency shutoff valve according to the present invention, and shows a portion corresponding to FIG. FIG. 2 is a view taken in the direction of arrows AA in FIG. Note that the same parts as those of the emergency shut-off valve described in the conventional example are denoted by the same reference numerals, and redundant description will be omitted. 1 and 2, the opposite side of the end of the sensor shaft 13 that constitutes the operating mechanism 60 to which the sensor lever 14 is fixed is protruded from the hood 12 to the outside in a watertight and rotatable manner. The flow velocity display device 80 corresponding to
Is provided.

The flow rate display device 80 comprises a casing 84 in which the projecting portion 13A of the sensor shaft 13 is inserted in a watertight manner, a large gear 85A attached to the projecting portion 13A so as to be rotatable at the same time, and a small gear 85B meshing with the large gear 85A. A rotation amplifying mechanism 85 constituted by a gear train, an output shaft 85b of the rotation amplifying mechanism 85, that is, a pointer 81 fixed to the tip end of the small gear shaft 85b, and a flow rate display corresponding to a needle point 81A of the pointer 81. A circular scale plate 82 provided with a scale 83; a small gear shaft 85b is rotatably supported by the inner wall of the casing 84 and the center of the circular scale plate 82;
By closing the front end opening of the casing 84 in a watertight manner with a transparent material 86 made of a transparent resin plate or a transparent glass plate, the protruding portion 1 of the sensor shaft 13 in the casing 84 is formed.
3A, a rotation amplification mechanism 85, a small gear shaft 85b, a pointer 81, a circular scale plate 82, and the like are provided in a watertight manner.

The flow rate display scale 83 of the circular scale plate 82 is
The set flow velocity of the passing water flow F when the flow sensor 11 starts rotating, the flow velocity of the passing water flow F when the flow sensor 11 is at an intermediate position between the start position and the end position, and the flow sensor 11 is the end position. The flow velocity of the passing water flow F immediately before the emergency shutoff valve is shut off by rotating to the vicinity and the flow velocity of the passing water flow F when the emergency shutoff valve is shut off when the flow sensor 11 is turned to the end position are different. Is provided based on the result of actual measurement using a current meter (not shown).

With such a configuration, when the flow rate of the passing water flow F in FIG. 8 exceeds the set value and the flow sensor 11 starts rotating, the rotation of the flow sensor 11 follows the rotation of the flow sensor 11 and FIG. The sensor shaft 13, which is a component of the operation mechanism 60 in FIG. 2, rotates. When the sensor shaft 13 rotates, the small gear shaft 85b is amplified and rotated by the amplifying action of the rotation amplifying mechanism 85 composed of a gear train, and the hands 81 are largely rotated. The passing water flow F is displayed on the scale plate 82 of the flow velocity display device 80.
The flow velocity display scale 83 is provided so that the flow velocity of the pointer 81A can be checked.
By reading 3, the flow sensor 11 is located at two positions, a start position indicated by a solid line and an end position indicated by an imaginary line in FIG. Can be easily specified and confirmed.

Further, the flow rate of the passing water F when the flow sensor 11 starts rotating is equal to or greater than a set value, and the flow rate of the passing water flow F when the flow sensor 11 is at an intermediate position between the start position and the end position. The flow velocity, flow sensor 11 was rotated to near the end position, and the flow rate of the passing water flow F immediately before the emergency shutoff valve was shut off, and the flow sensor 11 was rotated to the end position, and the emergency shutoff valve was shut off. The flow rate of the passing water flow F at the time is also indicated by the indicator 81.
By reading the flow velocity display scale 83 corresponding to the stylus tip 81A, it can be easily confirmed. Therefore,
When the flow rate of the passing water flow F becomes equal to or higher than the set value, it is possible to accurately determine whether or not the emergency shutoff valve is shut off.

Next, another embodiment of the present invention will be described with reference to FIGS. In FIGS. 3 and 4, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the repeated description will be omitted.

3 and 4, a flow velocity display device 80 is provided corresponding to the latch lever 22 of the engaging / disengaging mechanism 20 constituting the operating mechanism 60. Even with such a configuration, the same operation and effect as those of the embodiment described with reference to FIGS. 1 and 2 can be obtained. 5 and 6
May be configured as shown in FIG. 5 and 6, the fulcrum 81B of the pointer 81 is rotatably attached to the hood 12.
Arc-shaped scale plate 82 having needle tip 81A fixed to hood 12
And the force point 81C of the pointer 81 is connected to the rod 21 of the engagement / disengagement mechanism 20 that constitutes the operation mechanism 60. Even with such a configuration, FIGS.
The same operation and effect as those of the embodiment described above can be obtained.

In each of the above embodiments, the scale plate 82
The flow sensor 11 is provided at two positions, a start position indicated by a solid line and an end position indicated by an imaginary line in FIG. A position display scale corresponding to the position of the flow sensor 11 and a position display scale corresponding to an arbitrary position between the start end position and the end position. You may make it possible to confirm.

[0026]

As described above, since the emergency shut-off valve of the present invention is constituted, the following special effects can be obtained.

That is, there is provided a flow rate display device including a pointer which operates in accordance with the operation of the operation mechanism, and a scale plate corresponding to the needle point of the pointer, and at least the scale plate of the flow rate display device has Since the flow velocity display scale that can check the flow velocity of the passing water flow is provided, by reading the corresponding flow velocity display scale with the needle point of the pointer, it is possible that the flow sensor is at two positions of the start end position and the end position. Of course, the position between the start position and the end position can be easily specified and confirmed, and the passing water flow when the flow sensor starts rotating is equal to or more than the set value. The flow velocity of the passing water flow when the flow sensor is at an intermediate position between the start end position and the end position, the flow velocity of the passing water flow immediately before the flow sensor rotates to near the end position and the emergency shutoff valve is shut off, and the flow rate
The sensor rotates to the terminal position, and the flow rate of the passing water flow when the emergency shutoff valve is shut off can be easily checked.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a main part of an emergency shutoff valve according to the present invention.

FIG. 2 is a view taken along the line AA of FIG. 1;

FIG. 3 is a side view showing another embodiment of the main part of the emergency cutoff valve according to the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a side view showing still another embodiment of a main part of the emergency shutoff valve according to the present invention.

FIG. 6 is a sectional view taken along line CC of FIG. 5;

FIG. 7 is a perspective view of a conventional self-powered emergency shutoff valve.

FIG. 8 is an enlarged longitudinal side view showing a relationship between a flow velocity detecting mechanism, an operating mechanism, and a linking mechanism.

FIG. 9 is a sectional view taken along line DD of FIG. 8;

FIG. 10 is a sectional view taken along line EE of FIG. 8;

FIG. 11 is an enlarged side view showing a relationship between a rotation mechanism and a link mechanism.

FIG. 12 is a sectional view taken along line GG of FIG. 11;

FIG. 13 is a longitudinal sectional side view showing the link mechanism in an enlarged manner.

FIG. 14 is a sectional view taken along line HH of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve box 2 Valve body 3 Valve rod 11 Flow sensor 40 Torque generating source 60 Operating mechanism 70 Linkage mechanism 80 Flow rate display device 81 Pointer 82 Scale plate 83 Flow rate display scale F Flowing water flow

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H052 AA02 BA35 CC01 CD01 CD09 DA06 EA02 3H061 AA02 BB06 CC30 EA04 EA08 EA12 EB04 EB10 EC02 ED01 FC06 GG02 GG15 3H065 AA02 BA01 BA05 BA06 BB01 BC01 BC03 BC11

Claims (1)

[Claims] 1. A cylindrical valve box having both ends opened in an axial direction, a valve stem having an axis intersecting the axial direction in the valve box and rotatably supported around the axis. A valve body that is fixed to the valve stem, is rotated around the axis of the valve stem at the same time as the valve stem inside the valve box, and is opened and closed to allow or block water flow in the valve box; A torque source fixed to the outlet portion and constantly energizing the valve body with its own weight torque in the valve closing direction via the valve rod, and detecting the flow velocity of the passing water flow inside the valve box to detect the flow velocity of the passing water flow. A flow sensor that rotates in a region equal to or greater than a set value, an operation mechanism that operates outside the valve box following the rotation of the flow sensor, and the operation mechanism and the valve rod out-of-valve outlet portion of the valve stem are connected. And when the flow rate of the passing water flow is less than a set value and the operation mechanism is stopped, the operation mechanism is engaged with the operation mechanism and the torque generation source is engaged. The rotation of the valve stem and the valve body in the valve closing direction due to its own weight torque is prevented so that the valve body is maintained in the fully open position, and the operation of the operation mechanism releases the engagement with the operation mechanism, thereby reducing the torque. An emergency shut-off valve including a linkage mechanism that allows the valve stem and the valve body to rotate in the valve closing direction by the weight torque of the source, and a guide that operates with the operation of the operating mechanism; An emergency shutoff valve, comprising a flow rate display device having a corresponding scale plate, and a flow rate display scale capable of confirming at least the flow rate of the passing water flow is provided on the scale plate of the flow rate display device. .