KR0181711B1 - Fluid pump apparatus and valve device - Google Patents

Abstract

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Description

Fluid press-

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an embodiment of a fluid press-feeding device according to the present invention;

FIG. 2 is a partially enlarged cross-sectional view of the recess of FIG.

FIG. 3 is an enlarged cross-sectional view showing a second embodiment of the fluid press-feeding device according to the present invention. FIG.

FIG. 4 is a cross-sectional view showing a third embodiment of the fluid press-feeding device according to the present invention. FIG.

FIG. 5 is a sectional view showing a fourth embodiment of the fluid press-feeding device according to the present invention. FIG.

6 is an enlarged view of a passage portion of the fluid pressure feeding device according to the present invention.

7 is a cross-sectional view of the fluid press-feeding device according to the present invention used for an ultra-high pressure pump.

FIG. 8 is an enlarged cross-sectional view of the valve device used in FIG. 7; FIG.

FIG. 9 is an exploded perspective view of the valve device of FIG. 8; FIG.

FIG. 10 is a top view of the valve housing of the valve device of FIG. 8; FIG.

FIG. 11 is a sectional view taken along line A-A in FIG. 10; FIG.

FIG. 12 is a valve seat plan view of an eighth valve device; FIG.

FIG. 13 is a sectional view taken along line A-A of FIG.

Figures 14 and 16 are cross-sectional views showing a known valve device.

15 and 17 are exploded perspective views showing a known valve device.

DESCRIPTION OF THE REFERENCE NUMERALS

1: valve chamber 2: valve box

3: plunger 4: plunger box

5: Box 5a: Pressure acting chamber

6: entrance passage 7: exit passage

8: inlet valve 9: outlet valve

10: Fluid passage 11: Valve seat

12: valve body 13: spring

14: Fluid 15: Valve support

16: valve cover 17: passage

18: Groove 19: Selector

20: passage 21: cylinder

22: v- packing 23: elastic membrane

24: Oil passage 25: Working medium

27: selector 28: liquid

29: selector 30: storage room

32: second liquid 80: inlet side valve

81: outlet side valve 82: valve seat surface

83: toilet seat 84: valve seat

85: valve body 86: spring

87: valve housing 88: fluid passage

89: fluid passage 90: edge

91,92: Through hole

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a fluid pressure feeding apparatus for feeding fluid at ultra high pressure.

BACKGROUND ART [0002] Reciprocating pumps that pump a fluid such as water by opening and closing a valve by reciprocating motion of a piston are already known. Such a reciprocating pump is classified into a bucket type, a plunger type, and a piston type according to the shape of the piston. And it is selected and used in a specific form suitable for the purpose. A common problem with these pumps is that the sliding parts wear out easily. Therefore, in order to prevent wear of the sliding parts, it has been conventionally proposed to install a pipe in front of the piston to prevent the fluid passing through the valve from directly contacting the sliding part of the reciprocating pump, To thereby transmit the force of the piston (Japanese Patent Publication No. 48-35405).

However, according to this conventional configuration, since the diaphragm is in contact with the fluid, the diaphragm itself wears easily and the diaphragm must be replaced at any time. In particular, pumps used in cement plants frequently had to replace diaphragm.

For example, when the plunger pump is used for a cement mill, the pressure of the packing is limited to 200 kgf / cm ² or less because the cement particles rapidly wear on the packing.

The flow of fluid through the fluid pressure pump is controlled and adjusted by various valves. 14 and 15 show valves used in a plunger pump, which is a kind of high-pressure pump, which includes a tubular valve seat 100, a valve body 102 having an outer peripheral flange 101, And a valve spring 103 for pressing the valve body 102 toward the valve seat 100.

In the conventional plunger pump, the solids contained in the fluid can be sandwiched between the valve body 102 and the seat of the valve seat 100. The valve seat 100 used in such a conventional valve device is made to be easy to pass through solids and the valve seat 100 and the valve body 102 are made of metal, so that the gap between the valve seat 100 and the valve body 102 The valve opening / closing operation is not reliably performed. As a result, it is difficult to pump a certain amount of fluid at a constant speed, resulting in a reduction in work efficiency due to the use of the pump. Moreover, if the solids are sandwiched between the valve seat 100 and the valve body 102, there is a drawback that the valve seat and the surface of the valve body are damaged and the fluid leaks.

When the valve seat or the valve body is damaged in this way, the operation is interrupted and the valve unit is replaced.

Japanese Patent Application No. 62-237996 discloses a valve device which prevents the inflow of solids contained in the fluid and improves the durability of the valve. The valve device that is electrically powered includes a toilet seat 104 having a hemispherical entry surface 105 and a valve seat 107 having a hemispherical entry surface 105. The valve seat 107 described above A plurality of connected fluid passages 106 were formed. The valve device also includes a spherical valve body 108 having an outer circumferential surface corresponding to the shape of the concave surface 105 of the valve seat 107 and a spherical valve body 108 which urges the valve body 102 toward the concave surface 105 of the valve seat 107 And a spring retainer 111 for supporting both ends of the spring 109 to be engaged with the spring 109. [ In such a valve device, at least one of the valve seat 107 and the valve body 102 may be made of a hard elastic material or may be coated with an elastic material. For example, one of the valve seat and the valve body may be made of a hard elastic material and the other may be coated with a hard elastic material. It can also be made of wood instead of hard elastic material.

In the valve device having such a configuration, the fluid passage 106 formed in the valve seat 107 has a small diameter so as not to allow the solids to pass therethrough. Even if the solid matter passes through the fluid passage 106 and is sandwiched between the valve seat 107 and the valve body 108, the valve seat and / or the valve body are resilient so as not to interfere with the valve opening / closing function . However, in the conventional valve device described above, it is known that when the pressure of the pump is increased, the valve body 108 vibrates when the fluid is introduced, and therefore, it is not suitable when the pressure is transmitted to the high pressure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluid pressure feeding device for ultra-high pressure feeding of fluid.

One aspect of the present invention for achieving the object of the present invention is to provide a fluid press-feeding device for sucking fluid into a valve chamber by reciprocating motion of a piston provided in a cylinder and discharging the fluid from the valve chamber, And the valve chamber side is provided with a pressure reacting body for accommodating the working medium for transmitting the operation of the piston to the cylinder side divided by the pressure reacting body and the passage of the particles between the pressure reacting body and the valve chamber And a valve device provided with a separator.

According to another aspect of the present invention, there is provided a fluid press-feeding device for sucking fluid into a valve chamber by reciprocating movement of a piston provided in a cylinder and discharging the fluid from the valve chamber, wherein a pressure acting chamber is formed between the cylinder and the valve chamber, A liquid having a specific gravity different from that of the fluid is injected into the valve chamber so that the liquid discharged from the pressure chamber and the valve chamber can not flow out due to the difference in specific gravity between the liquid and the fluid, And a fluid press-feeding device.

The valve device includes a valve seat having a plurality of seats in the form of a hemispherical recess formed at regular intervals on the peripheral surface of the valve, a plurality of fluid passages formed in the seat to penetrate the valve seat, A valve body having a spherical surface corresponding to a semi-spherical recessed surface of the seat, and a valve housing provided with a pressing device for pressing the valve body toward the valve seat of the valve seat.

According to the present invention, when the piston performs the suction action, the pressure-applying body is contracted, so that a fluid having a volume corresponding to the volume change of the pressure-applying body flows into the valve chamber. At this time, the particles in the fluid exceeding the predetermined size are removed from the separator, so that they are not in contact with the pressure reactant. Subsequently, during the extrusion operation of the piston, the pressure acting body is expanded and the fluid in the valve chamber is extruded. The liquid contained in the pressure action chamber moves in the passage connecting the pressure action chamber and the valve chamber in accordance with the volume change of the pressure action body and the flow of the fluid. At this time, since the liquid in the pressure action chamber is different in specific gravity from the fluid, it moves only between the pressure action chamber and the liquid passage and does not flow into the valve chamber, and the fluid entering the valve chamber is discharged from the valve chamber without contacting the piston . In addition, in the case where the valve according to the present invention is composed of several toilet seats and a valve body, the operation of the valve is made to operate several times with a small amplitude, so that vibration due to opening and closing of the valve is prevented.

The present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a press-feeding device according to the present invention applied to a plunger pump used for feeding a fluid including fine particles such as cement powder.

1, the fluid pressure feeding device includes a valve box 2 in which a valve chamber 1 is formed, a plunger box 4 provided with a plunger 3, And a valve box 5 having a seal 5a.

The valve box 2 has an inlet passage 6 and an outlet passage 7 which are connected to the valve chamber 1 and passages 6 and 7 are provided with an inlet valve 8 and an outlet valve 9) was installed.

The inlet valve (8) and the outlet valve (9) each have a hemispherical recessed surface and a valve seat (11) having a plurality of fluid passages (10) in the form of a small hole formed in the axial direction from the recessed surface, A valve body 12 having a spherical surface corresponding to a hemispherical recessed surface and a valve spring 13 for urging the valve body 12 toward the valve seat 11. The fluid passage 10 of the valve seat 11 prevents solids particles exceeding a certain size present in the fluid 14 from entering the valve chamber 1.

The valve body 12 of the inlet side valve 8 is opened to the inside of the valve chamber 1 and the valve seat 15 connected to the valve spring 13, which is coupled to the inner wall of the valve chamber 1, And the valve body 12 of the outlet valve 9 is opened toward the outside of the valve chamber 1 and the valve spring 12 installed between the valve box 2 and the valve cover 16 13 to the valve seat 11 side.

The side wall 2a of the valve box 2 is provided with a passage 17 for connecting the pressure action chamber 5a and the valve chamber 1. The passage 17 is formed in the valve box 2 and the side wall 2a inwardly thereof. The groove (18) constitutes a part of the passage (17).

A selector 19 is provided between the groove 18 on the inside of the valve box 5 constituting the pressure acting chamber 5a and the pressure acting chamber 5a. This sorting device 19 may be constituted by a mesh screen or the like and the passage 20 composed of a plurality of fine holes is provided in the separator 19 to prevent particles exceeding a predetermined size from entering into the pressure action chamber 5a . The passage 20 may be formed directly on the side wall of the valve box 5 or may be inclined at a predetermined angle toward the passage 17.

A V-shaped packing 22 is provided in the cylinder 21 of the plunger box 4 and a plunger 3 is installed inside the cylinder 21. The plunger 3 has its inner end protruding into the pressure acting chamber 5a And was made to reciprocate at a high speed by a driving device (not shown).

The elastic membrane 23 divides the pressure acting chamber 5a into the cylinder 21 side A and the valve chamber 1 side B. The pressure acting chamber 5a is provided with an elastic membrane 23 inside the pressure acting chamber 5a. A working medium 25 such as oil is filled from the oil passage 24 of the plunger box 4 on the side 21 of the cylinder 21 divided by the elastic membrane 23.

The elastic membrane 23 is contracted by the suction operation of the plunger 3 so that the volume of the pressure acting chamber 5a on the side of the cylinder 21 side is reduced and a corresponding amount of fluid 14 Is introduced into the interior of the valve chamber 1. At this time, the solid particles having a particle size of a certain size or more are removed from the valve seat 11 and are not introduced into the valve chamber 1. Among the particles contained in the fluid 14 having passed through the valve, the solid particles having a particle size of a predetermined size or more are not filtered by the separator 19, and the particles in the fluid 14 flow into the valve chamber 1 Even if it flows into the valve chamber 1B of the pressure acting chamber 5a. The fluid 14 introduced into the chamber 1 is discharged to the outside of the valve chamber 1 while the elastic membrane 23 is expanded in accordance with the extrusion operation of the plunger 3 that follows.

FIG. 3 shows another example of the present invention. For convenience of explanation, the same reference numerals are used for the same components as those shown in FIG. In this example, the elastic membrane 23 was directly caught at the end of the plunger 3, and the plunger 3 was made to reciprocate while pushing the elastic membrane 23 directly. In this example as well, the passage 20 formed in the selector 27 is not disposed directly opposite the passage 17, but the passage 17 is disposed above the passage 17 so that any solid particles in the fluid 14 are discharged from the pressure- (5a). In the case of feeding a fluid containing large particles such as in a cement mill, liquid not containing solids particles such as water is injected into the valve chamber 1 side B of the pressure acting chamber 5a before starting the operation It is possible to prevent large solids particles in the fluid 14 from entering into the side of the valve chamber 1 side.

FIG. 4 shows a third embodiment of the pressure feeding device according to the present invention, wherein like reference numerals are used for the same parts as in FIG. In the third embodiment shown in Fig. 4, a passage 17 connecting the pressure acting chamber 5a and the valve chamber 1 is formed in the side wall 2a of the valve box 2. As described below, the position of the passageway 17 is determined by the specific gravity difference between the liquid 28 and the fluid 14. When the specific gravity of the liquid 28 is larger than the fluid 14, the passage 17 should be formed at a higher position in the pressure acting chamber 5a and when the specific gravity of the liquid 28 is lower than that of the fluid 14, The passage 17 should be formed at a lower position as in the case of FIG.

In the example shown in FIG. 4, the end of the passage 17 opened by the width of the pressure acting chamber 5a is located at a position higher than the inlet of the valve chamber 1. The position of the passage 17 is determined in consideration of the height of the valve chamber 1 of the pressure acting chamber 5a and the specific gravity of the liquid 28 and the fluid 14. [

A V-shaped packing 22 is provided in the cylinder 21 of the plunger box 4 and a plunger 3 is installed inside the cylinder 21. The plunger 3 has its inner end protruding into the pressure acting chamber 5a And is reciprocated at a high speed by a driving device (not shown).

The elastic membrane 23 divides the pressure acting chamber 5a into the cylinder 21 side A and the valve chamber 1 side B. The pressure acting chamber 5a is provided with an elastic membrane 23 inside the pressure acting chamber 5a. A working medium 25 such as oil is filled from the oil passage 24 of the plunger box 4 on the side 21 of the cylinder 21 divided by the elastic membrane 23. The side of the valve chamber 1 side B and the passage 17 of the pressure acting chamber 5a is filled with a liquid 28 such as oil which has a lower specific gravity than the fluid 14 but is not mixed with the fluid 14 . This liquid 28 is in contact with the fluid 14 in the passageway 17. This configuration is particularly useful for cement mills.

A separator 29 such as a mesh screen is provided between the pressure action chamber 5a and the passage 17 to prevent particles exceeding the particle size of a predetermined size from entering into the pressure action chamber 5a. This separator 29 was formed in the valve box 5 forming the pressure action chamber 5a and the passage 20 was formed to be inclined downward toward the passage 17.

The elastic membrane 23 is contracted by the suction operation of the plunger 3 so that the volume of the pressure acting chamber 5a on the side of the cylinder 21 is decreased and the pressure in the side of the valve chamber 1 . As the level of the liquid 28 in the passage 17 rises and the inlet valve 8 opens, a positive quantity of fluid 14 corresponding to the volume change enters the valve chamber 1 ≪ / RTI > The elastic membrane 23 is expanded together with the working medium 25 so that the volume of the valve chamber 1 side B is reduced and the valve chamber 1 of the pressure acting chamber 5a The liquid 28 on the side B is discharged through the passage 20. The discharged liquid 28 lowers the level of the liquid 28 in the passage 17 so that the outlet valve 9 is opened and a corresponding amount of the fluid 14 is extruded.

The liquid 28 is discharged only to the passage 17 and is not introduced into the valve chamber 1.

FIG. 5 shows a fourth embodiment of the fluid press-feeding device according to the present invention, wherein the same reference numerals are used for the same parts as in FIG. In this example, the valve box 5 is provided with the storage chamber 30 filled with the liquid 28. This storage chamber (30) is connected to the passage (17) by a branch tube (31). The contact point between the liquid 28 and the fluid 14 is prevented from moving upward beyond the storage chamber 30 so that the liquid 28 in the storage chamber 30 is replaced with a new liquid, (28) can always be kept fresh.

6 shows the relationship between the specific gravity of the liquid 28 and the fluid 14 between the liquid 28 and the fluid 14 in the pressure feeding device in which the liquid 28 is filled in the valve chamber 1 side B of the pressure acting chamber 5a. And a second liquid 32 as a separation medium which is not mixed with the liquid 28 and the fluid 14 while having a specific gravity in the middle of the specific gravity. According to this configuration, the liquid 28 and the fluid 14 are not in direct contact with each other. Other separation media which separate the liquid 28 and the fluid 14 may be used in place of the second liquid 32. [

According to the present invention described above, the liquid 28 may have a specific gravity lower than that of the fluid 14, or may have a specific gravity larger than that of the fluid 14. In this case, a passage connecting the pressure action chamber 5a and the valve chamber 1 may be formed above the pressure action chamber 5a. In this case, the premise is to adjust the positional relationship with respect to the height of the pressure acting chamber 5a and the valve chamber 1.

In the above-described examples of the present invention, the case where the elastic membrane 23 is provided in the pressure action chamber 5a has been described. However, the liquid 28 may be an oil-like material that is lubricant and is not mixed with the fluid 14 The elastic membrane 23 may be omitted.

FIG. 7 shows a fifth embodiment of the present invention applied to an ultra-high pressure feeding apparatus such as that used for cement mill, wherein the same reference numerals are used for the same components as in FIG. This type of ultrahigh pressure pressure feeding device includes a valve box 2 having a valve chamber 1, a plunger box 4 including a plunger 3 and a pressure acting chamber 4 provided between the valve box 2 and the plunger box 4, And a valve box 5 having a valve body 5a.

The valve box 2 has an inlet passage 6 and an outlet passage 7 connected to the valve chamber 1 and having an inlet valve 80 and an outlet valve 81. 8 and 13, the inlet valve 80 and the outlet valve 81 are each provided with a plurality of hemispherical recessed surfaces 83 spaced apart from each other at the surface 82 of the outer peripheral edge, A valve seat 85 having a spherical surface corresponding to the recessed surface of the seat 83 and a valve body 85 provided on the seat 83 having a spherical surface corresponding to the recessed surface of the seat 83, And a valve housing 87 provided with a spring 86 to be brought into close contact with the seat 83 of the valve seat 84.

A plurality of fluid passages 88 are formed in the respective seat 83 of the valve seat 84 so as to pass through the valve seat 84 in the axial direction. For convenience of illustration, three fluid passages 88 are shown in the respective seats 83. A fluid passage 89 in which the valve body 85 is installed is formed in the valve housing 7 at a position corresponding to the toilet seat 83 of the valve seat 84.

A flange-like edge portion 90 is formed at an outlet-side end of each of the fluid passages 89, and one end of the valve spring 86 is supported by the edge portion 90. The valve housing 87 and the valve seat 84 are formed with bolt holes 91 and 92 in a central portion thereof to receive a bolt 93 and a nut 94 inserted through the bolt holes 91 and 92, The valve housing 87 and the valve seat 84 are coupled and fixed.

The valve body 85 and / or the valve seat 84 may be made of a metal or other hard material, an elastic material such as synthetic resin, or an elastic material.

A passage 17 connecting the pressure action chamber 5a and the inside of the valve chamber 1 is formed in the side wall 2a of the valve box 2. The pressure action chamber 5a connected to the end of the passage There is provided a screen screen 29 or a similar structure of a mesh screen adapted to prevent the inflow of particles having a particle size larger than a predetermined size.

A cylinder 21 having a V-shaped packing 22 is provided in the plunger box 4 and a plunger 3 is provided in the cylinder 21 so as to protrude into the pressure acting chamber 5a. Is reciprocated at a high speed by a driving device (not shown).

The elastic membrane 23 dividing the pressure action chamber 5a into the cylinder 21 side A and the valve chamber 1 side is provided in the pressure action chamber 5a. The side of the cylinder 21 of the pressure acting chamber 5a is filled with a working medium 25 such as oil and the side B of the pressure acting chamber 5a on the side of the valve chamber 1 is filled with an oil The same liquid is filled so that the fluid can not enter the pressure acting chamber 5a.

According to this configuration, the elastic membrane 23 is contracted during the suction operation of the plunger 3, so that the volume of the pressure acting chamber 5a on the cylinder 21 side A is reduced. As a result, the valve body 85 of the inlet side valve 80 is opened while compressing the spring 86, so that the fluid 14 flows into the valve chamber 1. At this time, the valve body 85 of the outlet-side valve 81 is sucked toward their closed position, so that the outlet-side valve 81 is closed. The solid particles having a particle size of a certain size or larger when the fluid 14 flows into the valve chamber 1 are removed from the fluid passage 88 and are prevented from entering the valve chamber 1, Large particles of solid particles are removed from the separator 29, so that large particles can not enter into the pressure action chamber 5a. The elastic membrane 23 is expanded during the extrusion operation of the plunger 3 so that the fluid 14 introduced into the valve chamber 1 is extruded while opening the outlet port side valve 81. [

When the inlet-side valve 80 and the outlet-side valve 81 used in the present invention are formed in plural numbers, the opening and closing operations are performed even if the amplitude of the valve bodies 85 is small.

As described above, the fluid press-feeding device according to the present invention can be modified into various forms.

According to the fluid press-feeding device of the present invention, since the solid particles having a particle size of a predetermined size or larger are prevented from entering the valve chamber 1 or into the pressure acting chamber 5a, when the large particles come into contact with the valve parts The wear that can be exhibited and the damage caused thereby are reduced, so that the life of the pressure feeding device is prolonged. Further, when the present invention is applied to a pump, the pressure can be increased to 500 kgf / cm ² or more, so that the efficiency is greatly increased when it is used as a pressurizing operation in an ordinary engineering project. And the use of elastic membranes has the advantage of making the piston motion more comfortable.

Further, when a liquid having a specific gravity different from that of the fluid is injected into the pressure action chamber, it is possible to prevent the liquid from flowing into the valve chamber from the pressure action chamber and prevent the fluid from flowing into the pressure action chamber, There is an advantage that wear and cracks of the parts can be prevented.

In addition, when the reservoir for liquid storage is formed, the fresh liquid can always be contained in the pressure action chamber. When the separation medium is interposed between the liquid and the fluid, the liquid and the fluid are prevented from being mixed with each other. There is an advantage that the solid particles or dust in the fluid can be prevented from flowing into the pressure acting chamber. According to the above-described configuration, the sorter may be omitted. The use of a lubricant such as a piston lubricant on the cylinder side of the pressure action chamber has the advantage of extending the service life of the piston wear parts.

Particularly, in the present invention, if the valve is composed of a plurality of valve bodies and a valve seat, it is possible to prevent vibration due to the opening and closing operation of the valve and to improve the extrusion performance of the valve.

Claims (8)

The fluid to be pressure-fed by the reciprocating operation of the piston provided in the cylinder is sucked from the inlet passage 6 through the inlet valve 8 into the valve chamber 1 and is discharged through the outlet valve 9 to the outlet passage 7 In the fluid press-feeding device thus extruded, a pressure action chamber 5a is formed between the cylinder 21 and the valve chamber 1 to provide elastic membranes 23 and 26 in the pressure action chamber, (19) provided with a plunger (3) for transferring the operation of the piston to the inside of the cylinder side (A), and a passage (20) in which a solute larger than a predetermined size is not passed is formed in the passage (17) formed between the pressure action chamber and the valve chamber. 27, 29). The valve system according to any one of claims 1 to 3, wherein a liquid (28) having a different specific gravity from the fluid (14) to be pressure-fed is accommodated in the valve chamber side (B) of the pressure action chamber (5a) Characterized in that the passage (20) of the fluid is arranged at a different height so that the liquid (28) can not flow into the valve chamber due to the specific gravity difference between the liquid and the fluid to be fed. The fluid press-feeding device according to claim 2, wherein the device has a reservoir (30) for receiving the reserve liquid (28) and the reservoir (30) is connected to the passage (17) by the passage (31). 2. A method according to claim 2 wherein a second liquid (32) not mixed with the liquid (28) and the fluid (14) described above is received at the interface between the liquid (28) Characterized in that the liquid (32) is caused to move in accordance with the relative level fluctuation of the liquid (28) and the fluid (14). The fluid press-feeding device according to claim 1, wherein the working medium (25) for transmitting the operation of the piston to the cylinder side (A) of the pressure acting chamber (5a) is accommodated. The fluid press-feeding device according to claim 1, wherein the plunger (3) is provided so as to protrude into the pressure acting chamber (5a), and the elastic membrane (26) is seated to contact the outer circumferential surface of the plunger (3). The fluid press-feeding device according to claim 1, wherein the valve (8) provided in the inlet side passage (6) of the valve chamber is configured to inhibit the inflow of solids in the fluid exceeding a predetermined size. Characterized in that the passage (17) and the passage (20) are connected by a vertically formed recess (18) and the interface between the liquid (28) and the fluid (14) Pressure feeding device.

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