JP2020026844A - Forcible on-off valve mechanism for main valve - Google Patents

Abstract

To forcibly control opening of a main valve adaptively to various situations which cannot be coped with by normal functions of a normal pilot type back pressure valve and other pilot type automatic control valves.SOLUTION: A pilot type automatic control valve which has a main body 1 composed of a diaphragm valve is characterized in that: an upright pipe 21 having a predetermined height into which an upper part of a valve rod 18 projecting upward from a diaphragm 10 is inserted to be supported in a watertight state is projected on the main body 1; a nut 22 into which the valve rod 18 projecting outward from an upper-end opening part 21a of the upright pipe 21 is threadably inserted is detachably provided on an end face 21b of the upper-end opening part 21a; a cap 23 having a height higher than an upper-limit position of the valve rod 18 is detachably fitted to the upright pipe 21; and an adjusting screw 24 is threadably inserted into the inside of the cap 23 from an upper end face thereof so that its lower end is attached to and detached from an upper end of the valve rod 18 inside the cap 23.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a forced opening / closing valve mechanism of a main valve used for a pilot back pressure valve and other pilot type automatic control valves.

  For example, in countries with severe shortage of water resources, a sufficient water distribution network is not established, so that the desired amount of water supply can be secured in upstream water distribution areas such as near water purification plants and distribution towers, but away from upstream water distribution areas. Water supply pressure tends to be insufficient in the distribution area and high elevation areas, and a certain amount of water supply cannot be secured.

  Therefore, a pilot-type back pressure valve (see, for example, Patent Document 1) is provided at a key point in the piping route, and the distribution pressure on the upstream side of the water supply is controlled to evenly distribute the water supply amount from the upstream to the downstream end. It is possible.

Japanese Patent No. 3334198

However, if the water distribution network is not sufficiently prepared as described above, the water distribution pressure and the water distribution volume tend to be insufficient, and it is assumed that the situation cannot be controlled by the function of the pilot back pressure valve alone.
Such a problem is not limited to the above-mentioned pilot-type back pressure valve, but also has a problem that other pilot-type automatic control valves cannot be dealt with only by the original function of the valve.

  Therefore, in the present invention, forcibly opening and closing the main valve, the opening of the main valve can be forcibly controlled so as to cope with various situations that cannot be dealt with by the normal function of the pilot type back pressure valve and other pilot type automatic control valves. It is intended to provide a valve mechanism.

  In view of the above problems, the main valve forced opening / closing valve mechanism according to the present invention has an inlet and an outlet on the main body side, a primary flow path communicating with the inlet, and a secondary flow communicating with the outlet. The flow path and the inside of the main body are partitioned and the primary flow path and the secondary flow path are communicated through a valve port, and a main valve provided to open and close the valve port is closed by a valve spring. Energized in the valve direction, the inside of the main body is partitioned into a pressure chamber provided on the back side of the diaphragm and a primary flow path side by a diaphragm provided in connection with the main valve to form a diaphragm valve, and a diaphragm valve is provided. The pressure chamber is provided with a pilot valve port that communicates with the secondary flow path, and a pilot valve that opens and closes the pilot valve port is formed by applying an elastic force of a pressure setting spring to an upper surface and applying a primary pressure to a lower surface. Pilot-type back pressure valve connected to the response member and connected to the pressure chamber through the primary flow path via a throttle Alternatively, in a pilot-type automatic control valve that controls the power required to operate the main valve of the diaphragm valve by a pilot valve and opens and closes the main valve, the upper part of a valve rod projecting upward from the center of the diaphragm is inserted in a watertight manner. An upright pipe having a predetermined height to be supported protrudes from the upper part of the main body, and a nut into which a valve stem protruding outward from an upper end opening of the upright pipe is screwed is provided on an end face of the upper end opening so as to be detachable and attachable. A cap having a height higher than the upper limit position of the cap is detachably covered with the upright pipe, and an adjusting screw is threaded into the cap from the upper end face so that the lower end can be detached from the upper end of the valve rod inside the cap. It is characterized by the following.

In short, since the forced open / close valve mechanism of the main valve in the pilot type back pressure valve of the present invention has the above-described configuration, usually, a portion corresponding to the end face of the upper end opening portion of the upright pipe in the valve rod in the closed state of the main valve or the valve. By disposing the nut above the part and disposing the lower end of the adjusting screw at a height higher than the upper limit of the upper end of the valve rod with the main valve fully open, the fluid pressure on the primary side is maintained at a certain constant pressure. Then, the upstream water can be discharged to the secondary side in accordance with the change in the primary side pressure to function as a general back pressure valve for adjusting the primary side pressure.
When it is assumed that the primary side pressure drops below the set pressure due to excessive use of water on the secondary side at once, a part corresponding to the end face of the upper end opening of the upright pipe in the valve stem with the main valve closed. Or, by disposing a nut above the part and disposing the adjusting screw lower end at the valve stem upper end position corresponding to the opening degree smaller than the fully opened state of the main valve, the opening degree which should be fully opened is smaller than the full opening state. By controlling the flow rate appropriately, it is possible to prevent the exhaustion of the upstream (primary) water amount.
In addition, when a sufficient amount of water for operating the back pressure valve is not supplied to the primary side, a nut corresponding to the end face of the upper end opening of the upright pipe or a nut above the corresponding portion in the valve stem with the main valve closed. At the same time, the adjusting screw is screwed forward and the lower end of the valve rod is pressed until the main valve closes to shut off the primary and secondary sides to cut off water or to screw the nut. The main valve is forcibly held at a desired opening by pulling up the valve stem until the main valve properly holds an opening smaller than the full opening, and screwing the upper end of the valve stem so as to be pressed with the lower end of the adjusting screw. Or to secure a predetermined amount of water supply.
Furthermore, according to the present invention, the nut is screwed forward and the valve stem is pulled up only until the main valve is fully opened, and the back pressure function does not work. Because water can be passed through the flow path to the side flow path, for example, at the time of piping work, if a back pressure valve is interposed in the pipe, the back pressure valve functions, causing trouble to the piping work, In order to prevent the back pressure valve from malfunctioning, install a bypass pipe in parallel with the back pressure valve or attach a substitute pipe only for water flow by removing the back pressure valve once so that the back pressure valve in the piping does not function. After the plumbing work, the need for pre-work such as removing the bypass pipe and replacing the substitute pipe with a back pressure valve became unnecessary. Above, which cannot be dealt with with the normal back pressure valve function It can cope with seed situation.

  Further, the forced on-off valve mechanism according to the present invention forcibly controls the opening of the main valve by using a pilot-operated valve other than the pilot-type back pressure valve, such as a pilot-type pressure reducing valve or a pilot-type constant water level valve. Since the control can be performed, the flow rate can be adjusted in response to various situations that cannot be dealt with by the normal function of the pilot type automatic control valve.

1 is a longitudinal sectional view showing a closed state of a main valve in a normal use of a pilot-type back pressure valve equipped with a forced opening / closing valve mechanism according to the present invention. It is a longitudinal cross-sectional view which shows a full open state same as the above. It is an expanded sectional view of a pilot valve. It is an expanded sectional view of a stop. It is a principal part enlarged view of FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. It is a principal part expanded sectional view which shows the half open state when the upper limit of a main valve is set to half open by a forced opening / closing valve mechanism. It is a principal part expanded sectional view which shows the forcible closing state of the main valve by a forced opening / closing valve mechanism. It is a principal part expanded sectional view which shows the forced half-open state of the main valve by a forced opening / closing valve mechanism. It is a principal part expanded sectional view which shows the forced full open state of the main valve by a forced opening / closing valve mechanism.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The pilot type back pressure valve shown in the figure has a main body 1 composed of a diaphragm valve mainly composed of a valve box 2 and a bonnet 3, and is necessary for the operation of a main valve 13, which will be described later, housed in the diaphragm valve (main body) 1. This is a pilot (operating) type valve configured to open and close the main valve 4 by controlling the power (pressure difference between the primary side pressure and the secondary side pressure) by a pilot valve 27 described later.

  An inlet 4 and an outlet 5 are formed on the left and right sides of the valve box 2 on the same horizontal axis, and inside the valve box 2, a primary flow path 6 communicating with the inlet 4 and a communication with the outlet 5. A secondary channel 7 is provided, and the secondary channel 7 is partitioned by a partition wall 8 so that the secondary channel 7 is disposed inside and the primary channel 6 is disposed outside the secondary channel 7.

  The partition 8 has an upwardly opening valve port 9 whose axis is orthogonal to the axis of the inflow port 4, and the primary channel 6 and the secondary channel 7 communicate with each other through the valve port 9.

At the upper end of the valve box 2, an opening 2a communicating with the primary flow path 6 and the valve port 9 is provided, and the opening 2a is provided between the valve box 2 and the bonnet 3 covering the upper part thereof. It is closed by the intervening diaphragm 10.
In the opening 2a, a strainer 11 is provided around the valve port 9.

  The bonnet 3 is provided with a concave space defined inside the valve box 2 (primary side flow path 6 side) by a diaphragm 10, and the concave space corresponding to the rear surface (upper surface) side of the diaphragm 10 is pressurized. It has room 12.

  The diaphragm 10 has, on its lower surface, a main valve 13 having an annular lower surface protruding from the lower surface of the diaphragm 10 so as to correspond to a valve seat 9a provided around the valve port 9. In this manner, the main valve 13 is integrated with the diaphragm 10. By forming, the main valve 13 and the diaphragm 10 are connected.

  Diaphragm holders 14 and 14a are joined to the lower surface of the diaphragm 10 inside the main valve 13 and the upper surface of the diaphragm 10 corresponding to the main valve 13, respectively, and the valve opening 9 is provided in the cross direction of the lower diaphragm holder 14a. The four guide vanes 15 whose outer edges slide on the inner wall of the wing are suspended.

  Then, a coil-shaped valve spring 16 is interposed between the upper part of the pressure chamber 12 and the upper disk-shaped diaphragm retainer 14 by compression, and the main valve 13 is urged by the valve spring 16 in the valve closing direction. I have.

  Note that the upper end of the valve spring 16 is supported by being fitted to a flat inverted truncated cone-shaped convex portion 17 hanging down from the center of the upper portion (bonnet 3) of the pressure chamber 12.

  Further, a valve stem 18 penetrating through the center of the convex portion 17 of the bonnet 3 through the diaphragm retainer 14 at the center of the diaphragm 10 to protrude upward, and by controlling the position and state of the valve stem 18 on the bonnet 3, A forced opening / closing valve mechanism 19 for forcibly controlling the opening of the main valve 13 is provided.

  The forced opening / closing valve mechanism 19 has an upright pipe 21 having a predetermined height, which is inserted and supported in a watertight manner above the valve rod 18 by an O-ring 20 so as to protrude above the main body 1 (bonnet 3).

  A nut 22, into which a valve stem 18 projecting outward from an upper end opening 21a of the upright pipe 21 is screwed, is provided on the end face 21b of the upper end opening 21a so as to be detachable, and the valve stem 18 when the main valve 13 is fully opened is provided. A cap 23 having a height higher than the upper limit position is detachably covered on the upright tube 21.

  The cap 23 can be attached to and detached from the upright tube 21 by screwing and unscrewing a female screw threaded on the inner periphery of the lower end opening of the cap 23 to a male screw threaded on the outer periphery of the upright tube 21. The screw 22 is advanced and retracted with the cap 23 removed.

  An adjusting screw 24 is screwed into the upper end face of the cap 23 from the upper end face to the inside of the cap 23, and the lower end of the adjusting screw 24 can be attached to and detached from the upper end of the valve stem 18 inside the cap 23. A lock nut 24a is screwed onto the adjustment screw 24.

  A projecting port 25 communicating with the pressure chamber 12 projects upward from the outlet 5 side (right side in the figure) of the bonnet 3, and the projecting port 25 is provided with an inlet 28 of a pilot valve 27 through a throttle pipe 26. They are connected in a watertight manner.

  The pilot valve 27 is provided with an angle-shaped valve box 30 in which a flow path between an inlet 28 and an outlet 29 is at a right angle.In the valve box 30, a pilot valve port 31 is provided above the inlet 28 on the same axis as this, The pilot valve port 31 communicates with the secondary flow path 7 connected to the outlet 29 via the secondary communication path 32.

  A pilot valve seat 31a made of an annular ridge is provided on the upper end surface of the pilot valve port 31, and a child valve 33 which is detachably attached to the pilot valve seat 31a to open and close the pilot valve port 31 is provided at a lower end of the valve shaft. I have.

  The valve shaft 34 is provided at the center of the lower part of the funnel-shaped recess 35 provided in the upper part of the valve box 30, and is provided with an O-ring in a valve stem guide hole 36 formed on the same axis as the pilot valve port 31 below the recess 35. And is supported so as to slide in a watertight manner.

  Then, the flange provided around the upper open end of the concave portion 35 and the flange provided around the lower open end of the spring cover 37 covering the concave portion 35 are joined via a pressure responsive member 38 formed of a pilot diaphragm. The lower surface of the pressure responsive member 38 is fixed to the upper end of the valve shaft 34 to connect the slave valve 33 to the pressure responsive member 38, and the internal space of the concave portion 35 defined by the pressure responsive member 38 is used as a pilot pressure chamber. It is 39.

  A substantially disk-shaped spring receiver 40 joined to the upper surface of the pressure responsive member 38 and also serving as a diaphragm holder, and a lower end of an adjustment bolt 41 screwed into the inside of the spring cover 37 from the upper surface of a flat circular step portion 37 a protruding from the upper end of the spring cover 37. A pressure setting spring 42 is compressed and interposed between the spring member 40a and the abutting spring receiver 40a, whereby the elastic force of the pressure setting spring 42 acts on the upper surface of the pressure responsive member 38. Adjusted by moving.

  A lock nut 41a is screwed onto the adjusting bolt 41, and the adjusting bolt 41 is covered by a top cap 43 whose lower end opening can be externally screwed onto the flat circular step portion 37a.

  The pilot pressure chamber 39 connects a primary communication path 44 with the primary flow path 6 so as to apply a primary pressure to the lower surface of the pressure responsive member 38. The opening desired for the road 6 is covered with a strainer 45 (see FIGS. 1 and 2).

Further, the primary side flow path 6 and the pressure chamber 12 are separately communicated with each other through a primary side communication path 46, and a throttle 47 formed of a spiral narrow path is interposed in the primary side communication path 46. The fluid is gradually supplied to the pressure chamber 12 while controlling the pressure of the pressure chamber 12 when the valve port 9 is closed to eliminate the impact of a water hammer or the like when the valve is closed.
The opening desired for the primary side flow path 6 of the primary side communication path 46 is covered with a strainer 48 (see FIGS. 1 and 2).

In the pilot-type back pressure valve configured as described above, usually, a portion corresponding to the end face 21b of the upper end opening 21a of the upright pipe 21 in the valve rod 18 in the closed state of the main valve 13 or a portion thereof. A nut 22 is disposed above (in the illustrated example, seated on the upper end opening end face 21b, see FIGS. 1 and 5), and a height position equal to or higher than the upper limit of the upper end of the valve rod 18 when the main valve 13 is fully opened (the upper limit in the illustrated example). Position, see FIGS. 2 and 6), the lower end of the adjusting screw 24 is arranged.
By setting the forced opening / closing valve mechanism 19 in this way, it is possible to function as a general back pressure valve as described below.

  That is, when the primary pressure becomes higher than the set pressure, the pressure responsive member 38 resists the elastic force of the pressure setting spring 42 by the (primary) pressure of the fluid flowing into the pilot pressure chamber 39 from the primary communication passage 44. It is displaced upward (in the valve-opening direction of the child valve 33), whereby the child valve 33 is separated from the pilot valve seat 31a via the valve shaft 34, and the pilot valve port 31 is opened.

By opening the valve, the pressure chamber 12 communicates with the secondary flow path 7 through the secondary communication path 32.
Further, the pressure fluid flowing into the pressure chamber 12 from the primary communication path 46 does not stay in the pressure chamber 12 but flows down from the secondary communication path 32 to the secondary flow path 7 and the outlet 5.

  Then, since the pressure in the pressure chamber 12 drops until it becomes equal to the secondary pressure, the diaphragm 10 is displaced by the primary pressure so as to push up the diaphragm 10 in the valve opening direction, so that the main valve 13 is moved from the valve seat 9a. The valve port 9 is opened.

  Thereby, the inflow port 4 (primary side flow path 6) and the outflow port 5 (secondary side flow path 7) communicate with each other through the valve port 9, and the primary-side pressure fluid flows down to the outflow port 5 side, The primary pressure drops.

  When the primary pressure on the primary flow path 6 side becomes lower than the set pressure, the elastic force of the pressure setting spring 42 lowers the pressure responsive member 38 against the primary pressure in the pilot pressure chamber 39 (closes the child valve 33). In the valve direction), and conversely, the slave valve 33 is seated on the pilot valve seat 31a, and the pilot valve port 31 is closed.

  As a result, the connection between the secondary flow path 7 and the pressure chamber 12 is shut off, the primary side pressure fluid from the primary side communication passage 46 is supplied into the pressure chamber 12, and the inside of the pressure chamber 12 is The pressure becomes substantially the same as the pressure, and the diaphragm 10 is displaced in the valve closing direction (downward) of the main valve 13 by the elastic force of the valve spring 16, whereby the main valve 13 is seated on the valve seat 9a and the valve port 9 is closed. I do.

  Further, when it is assumed that the primary side pressure falls below the set pressure due to excessive use of water at once on the secondary side, when the main valve 13 is closed, the upper end opening 21a of the upright pipe 21 in the valve stem 18 is closed. A nut 22 is disposed (e.g., seated on the upper opening end surface 21b in the illustrated example) at a position corresponding to the end face 21b or above the same, and the opening degree of the main valve 13 is smaller than the fully open state (for example, a half open state in the illustrated example, FIG. 7)), the lower end of the adjusting screw 24 is arranged at the upper end position of the valve stem 18 so that the flow rate corresponding to the degree of opening smaller than the fully opened position can be achieved at the position that should be fully opened. Depletion can be prevented beforehand.

  Further, when a sufficient amount of water for operating the back pressure valve is not supplied to the primary side, it corresponds to the end surface 21b of the upper end opening 21a of the upright pipe 21 in the valve rod 18 in the closed state of the main valve 13. A nut 22 is arranged above the part or above the part (in the illustrated example, seated on the upper end opening end surface 21b), and the adjusting screw 24 is screwed until the main valve 13 closes the upper end of the valve rod 18 at the lower end. By pressing, the primary side and the secondary side are shut off to cut off the water (see FIG. 8), or the nut 22 is screwed up and the valve stem 18 is pulled up until the main valve 13 maintains an appropriate opening smaller than the full opening. At the same time, by screwing the upper end of the valve rod 18 so as to be pressed by the lower end of the adjusting screw 24, the main valve 13 is forcibly held at a desired opening and a predetermined amount of water is supplied (see FIG. 9).

  Further, according to the present invention, the nut 22 is screwed forward and the valve stem 18 is pulled up only until the main valve 13 is fully opened. Since water can be passed through the flow path from the flow path 6 to the secondary flow path 7 (see FIG. 10), for example, when a back pressure valve is interposed in the piping during piping work, the back pressure valve Function, which may hinder the piping work and cause the back pressure valve to malfunction.To prevent the back pressure valve in the piping line from functioning, connect a bypass pipe to the back pressure valve in parallel or remove the back pressure valve once. After installing the substitute pipe for the purpose of water flow only, and after the piping work, the preparatory work such as removing the bypass pipe and replacing the substitute pipe with the back pressure valve became unnecessary, the back pressure valve became unnecessary. Normal back pressure valve equipment, such as easy plumbing work while attached to piping It is possible to cope with the above various situations that cannot be dealt with by Noh.

  In the present embodiment, a pilot-type back pressure valve in which a forced opening / closing valve mechanism 19 is provided on the main body 1 composed of a diaphragm valve and the opening of the main valve 13 can be forcibly controlled in addition to the original back pressure function is shown. However, not only this pilot type back pressure valve, but also other pilot type pressure regulating valves (pressure reducing valves, differential pressure valves, etc.), pilot type solenoid valves, pilot type constant water level valves, and other pilot type automatic control valves, Similarly to the above, the forced opening / closing valve mechanism 19 can be applied to the main body 1, whereby the opening of the main valve 13 can be forcibly controlled according to various situations. It is also possible to respond to.

DESCRIPTION OF SYMBOLS 1 Main body 4 Inlet 5 Outlet 6 Primary flow path 7 Secondary flow path 9 Valve port
10 Diaphragm
12 Pressure chamber
13 Main valve
16 Valve spring
18 Valve stem
21 Upright pipe
21a Top opening
21b end face
22 nut
24 Adjustment screw
27 Pilot valve
31 Pilot valve port
38 Pressure responsive member
42 Pressure setting spring
47 Aperture

In view of the above problems, the main valve forced opening / closing valve mechanism according to the present invention has an inlet and an outlet on the main body side, a primary flow path communicating with the inlet, and a secondary flow communicating with the outlet. The flow path and the inside of the main body are partitioned and the primary flow path and the secondary flow path are communicated through a valve port, and a main valve provided to open and close the valve port is closed by a valve spring. Energized in the valve direction, the inside of the main body is partitioned into a pressure chamber provided on the back side of the diaphragm and a primary flow path side by a diaphragm provided in connection with the main valve to form a diaphragm valve, and a diaphragm valve is provided. The pressure chamber is provided with a pilot valve port that communicates with the secondary flow path, and a pilot valve that opens and closes the pilot valve port is formed by applying an elastic force of a pressure setting spring to an upper surface and applying a primary pressure to a lower surface. Pilot-type back pressure valve connected to the response member and connected to the pressure chamber through the primary flow path via a throttle Alternatively, in a pilot-type automatic control valve that controls the power required to operate the main valve of the diaphragm valve by a pilot valve and opens and closes the main valve, the upper part of a valve rod projecting upward from the center of the diaphragm is inserted in a watertight manner. the predetermined height standpipe of supporting projecting from the upper body, ChakuHanare capable provided nut screwed the valve stem to outward protrude from the upper opening of the standpipe to the end surface of the top opening, the valve stem Has a male screw having a length that can be pulled up by the screw advance of the nut until the main valve is fully opened, and a cap having a height higher than the upper limit position of the valve stem is detachably covered on the upright pipe, and the valve inside the cap is provided. An adjusting screw is screwed into and penetrated from the upper end surface of the cap so that the lower end can be attached to and detached from the upper end of the rod.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The pilot type back pressure valve shown in the figure has a main body 1 composed of a diaphragm valve mainly composed of a valve box 2 and a bonnet 3, and is necessary for the operation of a main valve 13, which will be described later, housed in the diaphragm valve (main body) 1. This is a pilot (operating) type valve that opens and closes the main valve 13 by controlling the power (pressure difference between the primary side pressure and the secondary side pressure) by a pilot valve 27 described later.

A nut 22 into which a valve stem 18 projecting outward from an upper end opening 21a of the upright pipe 21 is screwed is provided on an end surface 21b of the upper end opening 21a so as to be detachable therefrom. A cap 23 having a male screw (not shown) of a length that can be pulled up until the valve 13 is fully opened, and having a height higher than the upper limit position of the valve rod 18 when the main valve 13 is fully opened, is detachably attached to the upright pipe 21. It is crowned.

Claims (2)

  An inflow port and an outflow port are opened on the side of the main body, and a primary flow path communicating with the inflow port and a secondary flow path communicating with the outflow port are formed inside the main body, and the primary flow path and the secondary flow path are connected to each other. A main valve provided to open and close the valve port is urged in a valve closing direction by a valve spring, and a diaphragm provided in connection with the main valve is provided. The interior of the main body is partitioned into a pressure chamber and a primary flow path provided on the back side of the diaphragm, a pilot valve port communicating with the secondary flow path is provided in the pressure chamber, and a pilot valve for opening and closing the pilot valve port is provided. In a pilot type back pressure valve in which an elastic force of a pressure setting spring is applied to an upper surface and a lower surface is connected to a pressure responsive member that applies a primary pressure and a primary chamber is connected to a pressure chamber via a throttle, the diaphragm Upright of specified height to support the upper part of the valve stem protruding above the center in a watertight manner Is provided on the upper part of the main body, and a nut into which a valve stem projecting outward from the upper end opening of the upright pipe is screwed is provided on the end face of the upper end opening so as to be detachable, and has a height higher than the upper limit position of the valve stem. The main valve is characterized in that the cap is detachably covered with the upright pipe, and an adjusting screw is screwed through the upper end face of the cap so that the lower end is detachable from the upper end of the valve rod inside the cap. Forced on-off valve mechanism.   An inflow port and an outflow port are opened on the side of the main body, and a primary flow path communicating with the inflow port and a secondary flow path communicating with the outflow port are formed inside the main body, and the primary flow path and the secondary flow path are connected to each other. A main valve provided to open and close the valve port is urged in a valve closing direction by a valve spring, and a diaphragm provided in connection with the main valve is provided. In a pilot-type automatic control valve for partitioning the inside of the main body into a pressure chamber provided on the back side of the diaphragm and a primary flow path and controlling the power required for the operation of the main valve by a pilot valve to open and close the main valve, A nut in which a vertical pipe having a predetermined height is inserted at the upper part of the main body so as to penetrate and support the valve rod projecting upward from the center of the diaphragm in a watertight manner, and a valve rod protruding outward from an upper end opening of the vertical pipe is inserted. Is provided on the end face of the upper end opening so as to be detachable, and has a height higher than the upper limit position of the valve stem. A main valve characterized in that a cap is removably covered with an upright pipe, and an adjusting screw is screwed into and penetrated from the upper end surface of the cap so that the lower end can be detached from the upper end of the valve rod inside the cap. Forced on-off valve mechanism.

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