JP2000074236A - Pressure reducing type reverse flow preventing drain valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate draining of water, by arranging a first/second check valve in the up/down stream of an operating piston, receiving in an intermediate chamber thereof a relief valve operated by a primary differential pressure in the upstream of the first check valve, pressing the second check valve by the operating piston, and draining water. SOLUTION: Water in a side of a primary chamber 5, reducing a pressure by opening a faucet in a first check valve 16, goes into an intermediate chamber 6, flows into a secondary chamber 8 by press opening a second check valve 20, and leads to the faucet from a flow outlet 3. The check valves 16, 20, pressed by check springs 19, 21 by closing the faucet, are closed, a relief valve 29 stops leak of water to a side of a drain port 4 by a differential pressure of the primary chamber 5 and the intermediate chamber 6. In winter when water in a pipe is drained, an operating piston 23 is lowered down by a motor in a drive box 27, an annular packing 25 adheres to a water stop cylinder 11 to interrupt water in a side of a flow inlet 2, the operating piston is further lowered down, a tapered surface 37 presses a protrusion 22 and an escape protrusion 36 to press open the check valve 20 and the relief valve 29, and water in an outflow side pipe is discharged from the drain port 4. In this way, water in the pipe can be easily drained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-reducing backflow prevention type drain valve in which a drain valve used in a cold region has a function as a pressure-reducing backflow prevention device.

[0002]

2. Description of the Related Art Conventionally, in cold regions, in order to prevent freezing, a drain valve is installed at an unfreezing portion at the base of a pipe to drain water from a water pipe in a building, and the drain valve is manually operated or remotely operated by electric motor. The drain valve is operated to shut off the water from the inflow port, open the outflow port and the drain port, and discharge the water in the outlet pipe downstream of the drain valve from the drain port. In the case of electric remote control, it is often used on high floors. In particular, in the case of direct water supply, it is desirable to use a highly reliable pressure-reducing backflow preventer to maintain the safety of water supply.

This is because a relief valve operated by water pressure and a spring is provided between two check valves, and a pressure difference generated between the primary side and the secondary side due to the strength of the spring of the check valve is caused by a reverse pressure and a reverse siphon. When the pressure decreases to a certain value, the water on the secondary side is released from the relief valve to form a space, and its reliability is said to be comparable to that of the spout space.

[0004] However, in winter, there has been no material suitable for use in a cold region where water may freeze, and when it is absolutely necessary to use the device in such an atmosphere, as a measure to prevent freezing, heat insulation such as a heater is required. There is a disadvantage in that the cost must be increased because measures must be taken.

[0005] Therefore, the applicant has filed a Japanese Patent Application No. 8-32 as a pressure-reducing backflow preventer which can be used sufficiently even in severe cold regions.
No. 6617 has been disclosed. This is because the two check valves are forcibly opened with two operation rods from the outside of the valve box at the time of drainage, and the check valves are tilted as far as possible to the downstream side so that the position of the valve seat can be adjusted. It is designed to lower the residual water during drainage.

However, on the other hand, drain valves used on high floors are often operated electrically, so that the water can be easily drained with a single switch in a room.
There is an irrationality that the water cannot be drained from the pipe unless the depressurization type backflow preventer installed on the basement is operated.

[0007]

In view of the above, in the present invention, the drain valve itself is provided with a performance as a pressure-reducing backflow preventer, so that water can be easily drained from the piping. It is an object of the present invention to provide a decompression type backflow prevention type drain valve which is as compact as possible, inexpensive, and has a low head loss.

[0008]

Therefore, in the present invention, a first check valve, which is pressed by a first check spring generating a large differential pressure, is provided on the upstream side of the operating piston of the valve box on the downstream side. A second check valve pressed by a second check spring for generating a small differential pressure and having an axial center different from that of the operating piston is provided, and an intermediate chamber is formed between the two. Receiving the differential pressure between the secondary pressure of the intermediate chamber and the primary pressure upstream of the first check valve,
A release valve operated by a release spring is housed, and an outlet pipe and a drain port for water from the intermediate chamber are formed in the lower part of the valve box. The water in the side pipe is discharged.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first check valve is a lift valve of a valve seat type which operates in a direction perpendicular to an inflow port and an outflow port in consideration of ease of repair and compactness. The present invention is not limited to this. For example, the head may be installed in an oblique outflow direction to further reduce the head loss. Further, the valve seat itself can be removed for repair.

The second check valve is installed so as to intersect the operating piston from an oblique direction, but may intersect at right angles.

[0011] Although an example of a motor that opens and closes electrically is illustrated, it is needless to say that it may be manually operated, and it is common to select the water passing and draining state by moving the operating piston up and down. The rotation can be performed only.

The relief valve is normally operated by receiving a pressure difference between the primary pressure and the secondary pressure by the diaphragm, and is surely, but not necessarily, an essential component.

[0013]

FIG. 1 shows an embodiment of the present invention.
Is a valve box having an inflow port 2 at the left end, an outflow port 3 at the right end, and a drain port 4 at a lower portion. An upward first check valve seat 7 is formed between the primary chamber 5 and the intermediate chamber 6, and a second check valve seat 9 inclined downward 45 ° is formed between the intermediate chamber 6 and the secondary chamber 8. Two water stop cylinders 10 and 11 are provided. A relief valve seat 12 and an intermediate chamber bypass 13 are provided in the intermediate chamber 6, and a primary side bypass 15 is provided between the pressure receiving chamber 14 and the primary chamber 5.
To form

The first check valve 16 has a check piece packing 1 at its lower end.
7 is mounted, and the inside of the hood 18 is pressed by the first check spring 19 so as to freely move up and down. The second check valve 20 has substantially the same shape.
And the bonnet 1 is pressed by the second check spring 21.
8 can be freely moved up and down. Although the small-diameter projection 22 is formed at the distal end portion, the projection 22 may also be provided on the first check valve 16 so as to serve as both.

The operation piston 23 has the water stop cylinder 1
Two annular packings 24 and 25 that slide on 0 and 11 are mounted, and the upper end is connected to the drive shaft through a control shaft 26 in a drive box 27 via an operation shaft 26. Driven by a motor via The valve box 1 and the drive box 27 are connected by an upper lid 28.

The relief valve 29 accommodated in the intermediate chamber 6 has a relief piece packing 30 for closing the relief valve seat 12.
A relief ring 33 of the same diameter as the relief valve seat 12 is mounted, and the relief spring 33 locked on the relief valve seat 32 is provided.
Is always receiving a downward force. Further, a diaphragm 35 fastened to the valve box 1 by a diaphragm holder 34 separates the pressure receiving chamber 14 that receives the primary pressure and the intermediate chamber 6 that receives the secondary pressure. Reference numeral 36 denotes a small-diameter relief projection, which together with the projection 22 of the second check valve 20 operates the operating piston 23.
The lower end taper surface 37 receives a pressing force.

The figure shows a water-stop state in which the operation piston 23 is open and the faucet at the end is stopped. In this state, the relationship between the pressures P1 and P2 in the primary chamber 5 and the intermediate chamber 6 is P1-P2. =
In order to generate a large differential pressure of about 35 to 50 KPa, the second check valve 20 opens at a pressure as low as 710 mm or more above the water column from the upstream side, that is, so as to generate a small differential pressure. The strength of the second check spring 21 is determined in advance. The relief valve 29 is provided by a force obtained by multiplying the pressure difference between P1 and P2 acting on the diaphragm 35 through the intermediate chamber bypass passage 13 by the effective pressure receiving area of the diaphragm 35.
Presses the release spring 33, keeps the release piece packing 30 in close contact with the release valve seat 12 and stops water leakage to the drain port 4 side, and P2 is at least one more than P1.
When the pressure is lower by 4 KPa, the relief spring 3 starts to open the valve.
Determine the strength of 3.

When the faucet is opened from this state, the water in the primary chamber 5 is reduced in pressure by the first check valve 16 and enters the intermediate chamber 6, and the second check valve 20 is pushed open to further open the secondary chamber 8. , And reaches the faucet through an outflow pipe connected to the outlet 3 (not shown). If the faucet is closed, the check spring 19, 2
1, the check valves 16 and 20 return to the state shown in FIG. 1, and the check piece packing 17 comes into close contact with the first check valve seat 7 and the second check valve seat 9.

When the pressure on the outlet 3 side becomes higher than the pressure on the inlet 2 side, that is, when a so-called back pressure phenomenon occurs, as long as the second check valve 20 is working normally, the pressure in the secondary chamber 8 is maintained. Although the water does not flow back into the intermediate chamber 6, if foreign matter gets stuck in the second check valve 20 and water leaks, the pressure difference between P1 and P2 becomes small, and at least 14 KPa Is reached, the relief valve 29 is pressed by the relief spring 33, the relief piece packing 30 is released from the relief valve seat 12, and the backflow water is discharged from the drain port 4.

When the water is cut off due to the main pipe work and the pressure in the primary chamber 5 drops below the atmospheric pressure, the water in the outflow pipe tries to flow back to the primary chamber 5 due to the reverse siphon phenomenon. Backflow is prevented by the check valve 16 and the second check valve 20, and at the same time, the relief valve 29 is fully opened by the relief spring 33 and the negative pressure. At this time, if there is a leak due to the failure of the first check valve 16, air is sucked from the drain port 4 to reduce the negative pressure in the pipe.

In the winter, when it is desired to drain water from the pipes, although not shown, when a switch provided in the indoor control box is turned on, the motor in the drive box 27 rotates, and the drive shaft is driven via the reduction gear. At the same time, the operating piston 23 is also lowered via the operating shaft 26. At that time, first, the annular packing 25 comes into close contact with the water stop cylinder 11 to shut off the water on the inflow port 2 side, and further descends, and the tapered surface 37 presses the projection 22 and the relief projection 36 to perform the second check. The valve 20 and the relief valve 29 are pushed open, and the water in the outlet pipe is discharged from the drain port 4.

FIG. 2 is a sectional view of a main part of another embodiment of the present invention. In this embodiment, a small-diameter drain cylinder 38 is formed below the water stop cylinder 11 and the drainage cylinder 38 is provided to the operating piston 23. A small-diameter annular packing 39 that slides on the cylinder 38 is mounted. The upper lid 28 is extended downward to form a small-diameter water stop cylinder 10 therein. The relief valve 29 is not provided with the relief projection 36 of FIG. 1 so as not to be linked with the operating piston 23. Furthermore, the relief valve 29
Although the drain port 4 opened to the side and the lower end of the valve box 1 communicates with the drain side bypass passage 40, two drain ports may be provided without communication.

Although the figure also shows the water stopped state, when the operating piston 23 is lowered to the drained state, first, the annular packing 25 is in close contact with the water stopping cylinder 11 to shut off the water on the inflow side. Later, the annular packing 39 separates from the drain cylinder 38 while the tapered surface 37
, And the second check valve 20 is pushed open, so that the water in the outflow side pipe is discharged from the drain port 4.

At this time, since the water stop cylinder 11 has a larger diameter than the water stop cylinder 10, a downward water pressure acts on the operating piston 23 when the second check valve 20 is pushed open. There is an advantage that operation becomes easy. Further, in the water stop state shown in the drawing, the upward water pressure acting on the operation piston 23 is smaller than that in FIG. 1, which is advantageous in the durability of the device.

[0025]

As described above, in the present invention, the drain valve itself has the function of a pressure-reducing backflow preventer, so that drainage of piping can be easily performed, and a large differential pressure The first check valve that causes
At the time of drainage, the operation check piston is pushed open to open the drainage passage, and the second check valve that generates a small differential pressure is located, and a relief valve is provided in the intermediate chamber between them, making it very compact and conventional. Since the span is almost the same as that of the pressure-reducing backflow preventer, and there is no need to connect with joints, the head loss is small and the cost is low.
It is possible to provide a decompression type backflow prevention type drain valve for a cold district which has a large economic effect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a water stop state according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a main part of another embodiment of the present invention, also showing a water stop state.

[Explanation of symbols]

1 valve box 2
Inlet 3 Outlet 4
Drain port 5 Primary room 6
Intermediate chamber 7 First check valve seat 8
Secondary chamber 9 Second check valve seat 10, 11
Water stop cylinder 12 Relief valve seat 13
Intermediate chamber bypass 14 Pressure receiving chamber 15
Primary side bypass passage 16 First check valve 17
Check piece packing 18 Bonnet 19
First check spring 20 Second check valve 21
Second check spring 22 Projection 23
Operating piston 24, 25 Annular packing 26
Operation axis 27 Drive box 28
Top lid 29 relief valve 30
Release piece packing 31 Release annular packing 32
Release valve seat 33 Release spring 34
Diaphragm holding 35 Diaphragm 36
Relief projection 37 Tapered surface 38
Drain cylinder 39 Annular packing 40
Drain side bypass

Claims (2)

[Claims] 1. A first check valve, which is pressed by a first check spring for generating a large differential pressure, is provided upstream of an operation piston of a valve box. A second check valve pressed against a second check spring for generating a small differential pressure is provided to form an intermediate chamber therebetween, in which the secondary pressure of the intermediate chamber and the second pressure are set. 1 Receives the differential pressure of the primary pressure upstream of the check valve and accommodates a relief valve operated by a relief spring, and forms an outlet pipe and a drain port for water from the intermediate chamber in the lower part of the valve box. A pressure-reducing type backflow prevention type drain valve in which an operation piston presses a second check valve to discharge water in an outflow side pipe. 2. The pressure-reducing backflow prevention type drain valve according to claim 1, wherein at the time of drainage, the operating piston presses the relief valve together with the second check valve.