JP2005291407A - Backflow preventive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow anybody to make a periodic inspection, by confirming whether or not the function of a backflow preventive device operates by a simple method, by examining to confirm whether or not the backflow preventive device normally operates, by making the periodic inspection, due to having the problem of being unable to confirm whether or not the backflow preventive device is normally operated from an external part. <P>SOLUTION: A conductive passage for conducting a primary side flow passage and an intermediate chamber partitioned by a first check valve of the backflow preventive device, is formed by bypassing the first check valve. An opening-closing device openable-closable from the external part is arranged in its conductive passage. The valve is usually closed. When confirming operation, the primary side flow passage is conducted to the intermediate chamber. The first check valve artificially leaks, and a pressure difference between the primary side flow passage and the intermediate chamber reduces, and a relief valve is put in an operating state. The relief valve operates, and fluid of the intermediate chamber is drained from a drain port, and the operation of the relief valve can be confirmed. Since the operation of the relief valve can be confirmed by confirming drain from the drain port by opening the opening-closing device, anybody can confirm the operation. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a backflow prevention device that prevents backflow of a flow that flows from upstream to downstream. In particular, the present invention relates to a decompression-type backflow prevention device that prevents backflow of tap water in a water supply facility.

Conventionally, the decompression-type backflow prevention device is the most reliable backflow prevention device used as a device for preventing backflow to the water main, mainly incorporated in a direct connection type pressurized water supply device, etc. A first check valve is provided that allows flow from the passage to the intermediate chamber and prevents flow from the intermediate chamber to the primary flow path, and includes a primary flow path and an intermediate chamber defined by the first check valve. When the pressure difference is larger than the set value, the valve is closed, and when the pressure difference is smaller than the set value, the valve is opened, and a relief valve is provided to open the intermediate chamber to the atmosphere. Recently, the automation of household equipment has progressed, and the number of equipment connected directly to the water supply has increased, so that reduced pressure backflow prevention devices have also been incorporated into household equipment, making it easier to incorporate reduced pressure backflow prevention devices. It has also been made.

As the number of equipment connected directly to the water supply increases, the number of backflow accidents also increases. The safety of the backflow prevention device built into household equipment is studied, and even the backflow prevention device built into the equipment works regularly. The necessity of confirmation is recognized, and it is desired to provide an inspection device that can easily confirm the operation of the backflow prevention device.

An inspection port for checking the pressure reducing backflow prevention device used for a directly connected pressurized water supply device is provided with an inspection port for inspection by a specialist. However, it is unsuitable for the confirmation device for the backflow prevention device incorporated in the household equipment that the user must regularly check, and most other backflow prevention devices must be removed, disassembled and inspected.
JP 2003-240146 A JP 2003-239334 A Japan Water Works Association "Maintenance Guidelines for Water Supply Equipment 2004"

The problem to be solved is that there is no backflow prevention device that allows the user to check the operation periodically by a simple method.

In order to solve the above-described problem, the present invention is provided with a first check valve that allows the flow from the primary flow path to the intermediate chamber and prevents the flow from the intermediate chamber to the primary flow path, When the pressure difference between the primary flow path partitioned by the first check valve and the intermediate chamber is larger than the setting, the valve is closed, and when it is smaller than the setting, the relief valve is opened to open the intermediate chamber to the atmosphere. A conduit that connects the primary flow path and the intermediate chamber defined by the first check valve of the backflow prevention device is formed by bypassing the first check valve, and an opening / closing device that opens and closes the conduit is provided. Normally, the valve is closed and shut off, and the valve is opened when the operation is confirmed, and the primary side flow path and the intermediate chamber are electrically connected. It is characterized in that the safety of the backflow prevention device is confirmed by checking whether or not the relief valve operates in a state where the pressure difference is reduced.

A first check valve that allows a flow from the primary flow path to the intermediate chamber and prevents a flow from the intermediate chamber to the primary flow path is provided in the flow path, and is divided by the first check valve. When the pressure difference between the flow path and the intermediate chamber is larger than the set value, the valve is closed. When the pressure difference is smaller than the set value, the backflow prevention device equipped with a relief valve that opens the intermediate chamber to the atmosphere is free from leakage of the first check valve. Regardless of the presence or absence, if the pressure difference between the primary flow path and the intermediate chamber becomes small, the relief valve opens and the intermediate chamber is opened to the atmosphere to prevent backflow to the primary flow path. If the relief valve is opened, backflow is prevented and safety is ensured. In the present invention, a conduit that connects the primary flow path and the intermediate chamber of the backflow prevention device is formed by bypassing the first check valve, and an opening / closing device that opens and closes the conduit is provided, and is normally closed. When the operation is confirmed, the valve is opened so that the primary flow path and the intermediate chamber are connected, the pressure difference between the primary flow path and the intermediate chamber is reduced, and the first check valve is leaked in a pseudo state. Check whether the valve operates, and when the first check valve becomes abnormal and the pressure in the intermediate chamber approaches the pressure in the primary flow path, the relief valve operates normally to prevent backflow Therefore, anyone can check the operation of the backflow prevention device if the switching device can be easily opened or closed manually or electrically.

In the present invention, the flow path is provided with a first check valve that allows the flow from the primary flow path to the intermediate chamber and prevents the flow from the intermediate chamber to the primary flow path, and is partitioned by the first check valve. The reverse flow prevention device was installed with a relief valve that closed when the pressure difference between the primary flow path and the intermediate chamber was larger than the set value, and opened when the pressure difference was smaller than the set value to open the intermediate chamber to the atmosphere. A resistance such as a valve is provided in the path instead of a check valve, the relief valve is opened and closed by the pressure difference of the resistance, and the resistance is bypassed even if it is a backflow prevention device that prevents the backflow by opening the flow path to the atmosphere. A similar effect can be obtained by providing a guiding path that opens and closes the guiding path.

FIG. 1 is a longitudinal sectional view of an embodiment of a backflow prevention device according to the present invention. An intermediate chamber 3 is provided between the primary channel 1 and the secondary channel 2. Between the primary channel 1 and the intermediate chamber 3, the flow from the primary channel 1 to the intermediate chamber 3 is allowed, and the flow from the intermediate chamber 3 to the primary channel 1 is prevented. The first check valve 4 is attached to partition the primary side flow path 1 and the intermediate chamber 3. Similarly, the flow from the intermediate chamber 3 to the secondary flow path 2 is allowed between the intermediate chamber 3 and the secondary flow path 2, and the flow from the secondary flow path 2 to the intermediate chamber 3 is blocked. As shown, the second check valve 5 is attached to partition the intermediate chamber 3 and the secondary side flow path 2.

A DP lower chamber 8 communicating with the intermediate chamber 3 through the intermediate chamber guide path 9 is provided with a relief valve 6 that opens the intermediate chamber 3 to the atmosphere. The relief valve 6 is attached to a diaphragm 7 interposed between the DP upper chamber 11 and the DP lower chamber 8 communicated by the primary channel 1 and the primary conduit 12, and the pressure of the primary channel 1 is reduced. The force in the valve closing direction and the pressure in the intermediate chamber 3 become the force in the valve opening direction and are configured to open and close by the pressure difference. The relief valve 6 is pressed in the valve opening direction by a relief spring 6a. The discharge port 10 is a port for discharging the fluid discharged from the relief valve 6 to the outside.

An opening / closing device A is provided in which a communication hole 14 is formed in a partition wall 13 separating the intermediate chamber side and the primary flow path side, and the communication hole 14 can be opened and closed in a watertight manner from the outside.

FIG. 2 is an enlarged view of the switchgear A section. A communication hole 14 is formed in a part of the partition wall 13 partitioning the intermediate chamber side and the primary flow path side that partitions the DP lower chamber 8 and the primary conduit 12, and a valve seat 15 surrounding the communication hole 14 is formed on the primary conduit side. A valve rod 17 having a valve 16 formed on the end surface facing the valve seat 15 is inserted into a hole provided in the outer wall 21 of the primary channel 1 so that the valve 16 faces the valve seat 15 and is slidable in a watertight manner. The presser spring 19 presses the valve 16 against the valve seat 15 so that the communication hole 14 is closed in a normal state. The valve rod 17 is protruded to the outside, the opening / closing ring 18 is attached, the pulling of the opening / closing ring 18 pulls the valve rod 17 against the presser spring 19, the valve 16 is separated from the valve seat 15, and the communication hole 14 is opened. to enable. The presser plate 20 is used to hold the presser spring 19 and prevent the valve rod 17 from coming off.

When the primary flow path 1 is pressurized, the fluid in the primary flow path 1 opens the first check valve 4 against the first spring 4 a of the first check valve 4, It flows into the chamber 3, further opens the second check valve 5 against the second spring 5 a of the second check valve 5, and flows into the secondary flow path 2. When the primary-side flow path 1 of the fluid begins to flow into the intermediate chamber 3, the pressure P ₂ of the intermediate chamber 3, an amount corresponding to the valve opening against the first check valve 4 to the first spring 4a, primary ΔP is lower than the pressure P ₁ of the side channels 1. Accordingly, the relief valve 6 is pressed and closed in the valve closing direction by the difference between the product of the pressure receiving area of the diaphragm 7 and the pressure difference ΔP and the force of the relief spring 6a.

After the first check valve 4 and the second check valve 5 are closed, the pressure in the primary channel 1 is reduced or the pressure in the intermediate chamber 3 is increased to reduce the pressure difference ΔP, and the pressure received by the diaphragm 7 When the force of the product of the area and the pressure difference ΔP becomes smaller than the force of the release spring 6a, the release valve 6 is opened, the fluid in the intermediate chamber 3 is discharged from the discharge port 10, and the intermediate chamber 3 is opened to the atmosphere.

Therefore, regardless of the presence or absence of leakage of the first check valve 4, the second check valve 5, the diaphragm 7, etc., due to the pressure difference ΔP between the primary channel 1 and the intermediate chamber 3 and the force relationship between the release spring 6a, The relief valve 6 is opened, the intermediate chamber 3 is opened to the atmosphere, and the primary-side flow path 1 and the secondary-side flow path 2 are separated, so that the backflow of fluid to the primary-side flow path 1 is prevented. Therefore, the operation of the relief valve 6 is the most important, and if the relief valve 6 is activated, backflow is prevented. Further, when the relief valve 6 is opened and the fluid flows out from the discharge port 10, it is possible to know the abnormality of the first check valve 4, the second check valve 5, and the like.

When the primary flow path 1 is pressurized and closed downstream of the secondary flow path 2, the first check valve 4 and the intermediate flow chamber 1 correspond to the force of the first spring 4a. Therefore, the relief valve 6 is kept in the closed state. When the opening / closing device A is opened by pulling the opening / closing ring 18 of the opening / closing device A to bring the communication hole 14 into a conducting state, the primary flow passage 1 and the intermediate chamber 3 are conducted, and the leakage of the first check valve 4 is the same. As a result, the pressure difference ΔP between the primary flow path 1 and the intermediate chamber 3 is reduced, and the relief valve 6 is opened by the force of the relief spring 6 a, and the fluid in the intermediate chamber 3 flows out from the discharge port 10. If the relief valve 6 is abnormal such as sticking, the opening / closing ring 18 of the opening / closing device A is pulled to open the opening / closing device A and the communication hole 14 is made conductive. It is possible to know the failure of the relief valve 6 without flowing out from the discharge port 10.

FIG. 3 is a longitudinal sectional view of an embodiment of the backflow prevention device according to the present invention, which is an embodiment in which the opening / closing device A is installed in a clamping portion for interposing the diaphragm 7. FIG. 4 is an enlarged view of the opening / closing mechanism A part. A guide path 24 that communicates with the DP upper chamber 11 is provided in the sandwiching portion 22 of the DP upper chamber 11, a communication hole 14 is formed in a side wall that sandwiches the diaphragm 7 of the guide path 24, and a valve seat 15 that surrounds the communication hole 14 on the inner wall. A valve rod 17 penetrating the valve seat 15 so that the valve 16 faces the valve seat 15 and is slidably penetrated outside is assembled to form the switchgear A in the same manner as in the previous embodiment. On the clamping surface of the clamping part 23 of the DP lower chamber 8, a groove 25 facing the communication hole 14 of the clamping part 22 and continuing to the DP lower chamber 8 is excavated. A portion corresponding to the communication hole 14 of the diaphragm 7 is formed with a hole 27 so that the groove 25 and the communication hole 14 communicate with each other.

An opening / closing mechanism A is formed on the DP upper chamber side, and a conducting path for conducting the DP upper chamber 11 and the DP lower chamber 8 simply by collating and assembling the communication hole 14, the hole 27 of the diaphragm 7, and the groove 25 of the DP lower chamber 8 Is formed via the opening / closing mechanism A, and the DP upper chamber 11 and the DP lower chamber 8 are electrically connected by opening the opening / closing mechanism A. The operation is the same as in the first embodiment.

FIG. 5 is a longitudinal sectional view of an embodiment of another type of backflow prevention device according to the present invention, which is an embodiment in which an opening / closing device A is installed in a clamping portion for interposing a diaphragm 7. FIG. 6 is an enlarged view of the opening / closing mechanism A part. This backflow prevention device has a structure in which the first check valve 4 and the relief valve 6 operate in conjunction with each other. When the primary channel 1 is pressurized, the fluid in the primary channel 1 pushes down the diaphragm 7 against the A spring 28 and the B spring 29 and opens the first check valve 4. Then, the air flows into the intermediate chamber 3 and further opens the second check valve 5 against the second spring 5 a of the second check valve 5 and flows into the secondary flow path 2. When the fluid in the primary channel 1 starts to flow into the intermediate chamber 3, the pressure P _{2 in} the intermediate chamber 3 pushes down the diaphragm 7 against the first check valve 4 against the A spring 28 and the B spring 29. The pressure P is lower than the pressure P ₁ of the primary flow path 1 by the amount of valve opening. Therefore, the relief valve 6 is pressed and closed in the valve closing direction by the force of the product of the pressure receiving area of the diaphragm 7 and the pressure difference ΔP and the force of the A spring 28 and B spring 29. The A spring 28 presses the relief valve 6 toward the opening side, and the B spring 29 is biased to close the first check valve 4.

After the first check valve 4 and the second check valve 5 are closed, the pressure in the primary channel 1 is reduced or the pressure in the intermediate chamber 3 is increased to reduce the pressure difference ΔP, and the pressure received by the diaphragm 7 When the force of the product of the area and the pressure difference ΔP becomes smaller than the force of the A spring 28, the relief valve 6 opens, the fluid in the intermediate chamber 3 is discharged from the discharge port 10, and the intermediate chamber 3 is opened to the atmosphere. Accordingly, a difference corresponding to the force of the B spring 29 is maintained in the pressure difference between the first check valve 4 and the relief valve 6 so that the relief valve 6 does not malfunction. The other operations are the same as those of the backflow prevention device described above.

This embodiment assumes that it is produced by plastic molding, except that the conduit 24 is formed by excavating a groove and butting the valve seat plate 26 provided with the communication hole 14 and the valve seat 15 from the diaphragm clamping surface side. This is the same as the previous embodiment. FIG. 7 shows an embodiment in which the guide path 24 is provided on the DP lower chamber side in the same manner as described above, and the rest is the same as the above embodiment.

FIG. 8 is a longitudinal sectional view of an embodiment of the backflow prevention device according to the present invention. In this embodiment, the switchgear A is formed independently, and the switchgear A can be attached at a position away from the backflow prevention device. is there. The primary side flow path 1 and the intermediate chamber 3 are respectively provided with connection ports 30 and 31 and connected to the connection ports 34 and 35 of the switchgear A through the pipes 32 and 33, respectively. 3 is formed so that the primary side flow path 1 and the intermediate chamber 3 are in a conductive state by forming a conducting path that conducts 3 and opening the switch A. Other operations and the like are the same as those in the above-described embodiment.

1 is a longitudinal sectional view of an embodiment of a backflow prevention device according to the present invention (Example 1). Enlarged view of the switchgear A part of the longitudinal section mentioned above 1 is a longitudinal sectional view of an embodiment of a backflow prevention device according to the present invention (Example 2). Enlarged view of the switchgear A part of the longitudinal section mentioned above Vertical sectional view of one embodiment of another type of backflow prevention device according to the present invention (Example 3) Enlarged view of the switchgear A part of the longitudinal section mentioned above The longitudinal cross-sectional enlarged view of the switchgear A part in the Example which changed a part of switchgear A of the above-mentioned Example. Longitudinal sectional view of an embodiment of a backflow prevention device according to the present invention (Example 4)

Explanation of symbols

1 --- Primary flow path 2--Secondary flow path 3--Intermediate chamber 4--1st check valve 5--2nd check valve 6--Relief valve 7- -Diaphragm A--Opening and closing device 14-Communication hole 15-Valve seat 16-Valve 17-Valve rod 26-Valve seat plate 28-A spring 29-B spring 32-Pipe 33- -tube

Claims (2)

A first check valve that allows a flow from the primary flow path to the intermediate chamber and prevents a flow from the intermediate chamber to the primary flow path is provided in the flow path, and is divided by the first check valve. When the pressure difference between the flow path and the intermediate chamber is larger than the set value, the valve closes, and when the pressure difference is smaller than the set value, the reverse flow prevention device equipped with a relief valve that opens the intermediate chamber to the atmosphere. The primary flow path and the intermediate chamber can be in a conductive state by forming a conducting path that bypasses the first check valve, providing an opening / closing device that opens and closes the conducting path, and opening the opening / closing device. Backflow prevention device A first check valve that allows a flow from the primary flow path to the intermediate chamber and prevents a flow from the intermediate chamber to the primary flow path is provided in the flow path, and is divided by the first check valve. When the pressure difference between the flow path and the intermediate chamber is larger than the set value, the valve is closed. When the pressure difference is smaller than the set value, the backflow prevention device is provided with a relief valve that opens the intermediate chamber to the atmosphere. By opening a communication hole that opens and closes the communication hole by opening a communication hole that connects the primary flow path and the intermediate chamber in the partition wall that partitions the primary flow path side and the intermediate chamber side. Backflow prevention device that enables the primary flow path and the intermediate chamber to be in a conductive state.

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