EP1793176A2 - Pipe disconnector with enhanced sealing force - Google Patents

Abstract

A spring (60) biases release valve (34) along opening direction of release valve and counteracts a pressure difference between inlet pressure and middle pressure. A hollow space is connected to the middle pressure space (66) and is arranged between the release valve and casing (10). A shiftable seat is located in hollow space and moved along opening or closing direction of release valve. A casing fixed stop is provided in upstream side of valve seat (32) in casing. The shiftable seat is moved with respect to release valve and contacted with casing fixed stop.

Description

Technical area

The invention relates to a system separator for physically separating an upstream liquid system from a downstream liquid system by means of a drain valve depending on the pressure drop between upstream and downstream liquid system, with an upstream backflow preventer, a downstream backflow preventer and a piston designed as a discharge valve body, which is arranged between the fluid flow between the backflow preventer wherein upstream of the upstream backflow preventer an inlet pressure of the upstream liquid system, between the drain valve body and the downstream backflow preventer a mean pressure in a medium pressure space and downstream of the downstream backflow preventer an outlet pressure of the downstream liquid system, and wherein on the drain valve body the pressure difference between inlet pressure and mean pressure Counteracts the closing direction of a force acting in the opening direction on the discharge valve body loading spring, wherein the discharge valve body on the downstream side has an effective for the medium pressure pressure surface, which is smaller than the effective pressure for the input pressure surface, whereby a cavity is formed by the Ablaßventilkörper, and the cavity communicates with the medium-pressure space.

System separators or pipe dividers serve to safely prevent backflow of liquid from a downstream liquid system into an upstream liquid system. The upstream fluid system may be a drinking water system. The downstream fluid system may e.g. to be a heating system. It is essential to prevent contaminated water from the heating system from flowing back into the drinking water system when the heating system is being refilled or refilled, for example by the pressure in the drinking water system collapsing for some reason. There are so-called. Backflow preventer. These are spring-loaded valves which allow fluid flow in only one direction, namely from the upstream to the downstream system. However, such backflow preventers can become leaky. Therefore, e.g. For drinking water and heating water, a separation of the liquid systems alone by backflow preventer not allowed. There must be a physical separation of the fluid systems so that in case of failure between the systems a connection to a drain and to the atmosphere is made.

System or pipe dividers include an upstream backflow preventer connected to the upstream liquid system and a downstream backflow preventer connected to the downstream system. Between the backflow preventers is disposed a pressure controlled dump valve which establishes a passage from the upstream liquid system to the downstream liquid system when there is a sufficient pressure differential between the two liquid systems so that the liquid can safely flow only from the upstream to the downstream liquid system. If this pressure drop does not exist, the drain valve establishes a connection of the space between the backflow preventer with the atmosphere and a drain.

In known pipe separators, the drain valve is a displaceable in a fitting housing piston. This piston has a central passage and at its downstream end face an annular valve seat, which comes to a valve-tight ring seal axially to the plant. The passage then establishes an atmosphere-closed connection between the upstream and downstream fluid systems. The upstream backflow preventer sits in the passage. As a result, the pressure difference between the inlet pressure in the upstream fluid system and a mean pressure acting in a medium pressure space between the piston and the downstream non-return valve acts on the piston against an opening-acting spring. For a flow to the downstream system can take place, even this pressure difference must exceed a predetermined, determined by the spring force measure.

If - as an example - a standing under low water pressure heating system from a drinking water system to be filled through the system separator, the piston of the drain valve is first pressed against the action of the spring acting thereon in its operating position by the input pressure in the drinking water system, in which he the connection to Atmosphere and interrupts the process and establishes a connection between drinking water system and heating system. Then, the upstream and downstream backflow preventers are pressed. It streams drinking water to the heating system and fill it up or down. The heating system is then filled to an outlet pressure that is below the inlet pressure. In normal operation, the difference between inlet pressure and outlet pressure is determined by the pressure drop across the backflow preventers, that is, by the strength of the return valve springs. The intermediate pressure is in accordance with the pressure drop across the upstream backflow preventer and the pressure drop across the upstream backflow preventer. The pressure difference between the inlet pressure and the mean pressure must be greater than a limit determined by the loading spring of the valve body of the drain valve.

In the valve seat of the drain valve, a seat seal is arranged. This is acted on the one hand by the medium pressure. On the other hand, with the drain valve closed, the force of the drain valve body acts on the seal. If this force is not large enough, there is a risk of insufficient gasket.

The force of the discharge valve body acting on the seal corresponds to the force exerted by the upstream liquid system minus the force exerted on the discharge valve body in the medium pressure space and the constant spring force of the spring acting on the discharge valve.

If the effective areas of the discharge valve are changed with unchanged pressure conditions in the inlet and in the medium-pressure space, the respective forces also change. By reducing the seat diameter of the valve seat of the drain valve so a greater sealing force can be achieved. At an effective for the inlet pressure area, which is greater than for the medium pressure, another effect occurs: the force acting in the closing direction force is so high at high pressures that the valve does not open.

State of the art

In the DE 20 2005 008 021 U1 a system separator is described in which a stepped piston is guided as a drain valve body in a two-part housing. The stepped piston forms with a seat edge and an annular valve seat a drain valve. The valve seat has a smaller diameter than the input-side outer diameter of the stepped piston. The formed between the piston outer side and the housing, hollow annular space is limited on the side of the medium-pressure space with a housing-fixed, clamped between the input-side and output-side housing, annular housing partition. About a hole in the mantle of the stepped piston, the hollow annulus is hydraulically connected to the medium-pressure chamber. The loading spring acting on the bleed valve body is disposed around the outside of the stepped piston. The housing partition wall forms the spring abutment. This arrangement is complex and bulky.

Disclosure of the invention

It is an object of the invention to provide a system separator of the type mentioned with improved sealing force.

According to the invention the object is achieved in that a movable in the direction of movement of the Ablassventilkörpers sliding seat is provided in the cavity, which is opposite the Ablassventilkörper movable up to a housing fixed stop, which is arranged in the flow direction in front of the valve seat of the drain valve.

In this way, a smaller valve seat for the drain valve can be realized with a correspondingly higher sealing force without the drain valve no longer functioning at high inlet pressures. A reduced diameter valve can be used which works well at both high and low inlet pressures.

As the inlet pressure increases, the drain valve is first closed. Subsequently, the backflow preventer opens. Then prevails in the medium pressure chamber compared to the prevailing atmospheric pressure increased pressure. Via the connection between the cavity and the medium-pressure space, an increased pressure is built up in the cavity. This pressure acts on the movable sliding seat. The sliding seat is moved in the direction of the valve seat to the stop fixed to the housing. Conversely, the pressure in the cavity between the sliding seat, the housing and the drain valve body also acts "from the back" on the protruding part of the drain valve body. The effective area for the medium pressure is not reduced in this way despite smaller valve seat. Thus, the balance of forces on the drain valve body remains the same with reduced valve seat size. However, the sealing force is greater because the seal has a smaller area. Accordingly, the contact pressure and the quality of the seal increases.

Preferably, the outlet-side diameter of the discharge valve body is smaller than the inlet-side diameter, and the sliding seat is formed by an annular sleeve, which is movably guided in the cavity formed by the difference in diameter between the drain valve body and housing. The discharge valve body thus forms a cavity between the housing and the piston between the inlet-side, thicker end and the outlet-side end. In this cavity, the sleeve can move. The housing-fixed stop can be formed by an annular step inside the housing. At medium pressure in the cavity, the sleeve is pressed against the stop. The housing then absorbs part of the pressure. In this way, a particularly compact arrangement is achieved.

In one embodiment of the invention, the annular sleeve has an L-shaped cross-section, one leg of which comes to rest with the inside when exposed to medium pressure on the stop.

A channel may be provided for connecting the interior of the discharge valve body with the cavity, which is formed in the region between the housing, the drain valve body and the sliding seat. This channel can be made, for example, by a simple bore or annulus with lands. The channel of the cavity may initially extend radially inwardly and then in the axial direction downstream of the medium-pressure space.

In a preferred embodiment of the invention, a first seal is provided, which is arranged in an annular groove on the outside in the drain valve body in the region of larger diameter and a second seal, which is arranged in the cavity between the channel and the movable sliding seat. In a particularly compact embodiment of the invention, the backflow preventer, the drain valve body, the loading spring, the housing and the sliding seat are arranged coaxially.

Embodiments of the invention are the subject of the dependent claims. An embodiment is explained below with reference to the accompanying drawings.

Brief description of the drawings

Fig.1

is a cross section through a system separator with two backflow preventer and a drain valve

Fig.2

shows a section of the system separator of FIG. 1 with the inlet-side backflow preventer and the open drain valve.

Figure 3

shows the detail of Figure 2, in which the discharge valve is closed, but with closed backflow preventer no pressure in the medium-pressure zone has been established.

Figure 4

shows the detail of Figures 2 and 3, in which the discharge valve is closed and in the medium-pressure zone with the backflow preventer open, there is an increased pressure.

Description of the embodiment

In Fig.1, 10 denotes a tubular fitting housing. The fitting housing 10 has an inlet 12 and at the opposite end an outlet 14. In the fitting housing 10, a cylindrical chamber 16 is formed. In the chamber 16, a piston-shaped valve body 18 is guided. From the chamber 16 is a Ablas 20, which has a connected to the atmosphere outlet pipe 22.

The valve body 18 is sealingly guided in the cylindrical chamber 16 on its lateral surface 24 with a seal 26. At its downstream end face 28, the valve body 18 forms an annular valve seat 30. The valve seat 30 abuts a seat seal 32 in the downstream end position shown in FIG. With the lateral surface 30 of the valve body 18 covers the Ablas 20. This is a drain valve 34th

The valve body 18 has a central passage 36. On the valve body 18, an inwardly projecting, annular disk-shaped edge 38 is formed at the upstream end. In the passage 36 sits an upstream backflow preventer 40. In the housing 42 of the backflow preventer sits a valve seat 44. The valve seat 44 cooperates with a valve closing body 46. The valve closing body 46 has a head 48 and a shaft 50. The shaft 50 is guided in an opening 61 of the housing 42. The shaft 50 is surrounded by a coil spring 52. The coil spring 52 is guided with one end 54 in an annular groove 56 in the housing 42 and abuts the head 48 with the other end 58.

A coil spring 60 is supported on a shoulder 62 on the inside of the fitting housing 10 and abuts upstream on the downstream, rear side of the valve body 18. As a result, the valve body 18 of the discharge valve is loaded by the spring 60. The spring 60 ensures that the drain valve is always open without further forces.

Downstream of the arrangement described, a backflow preventer 64 is seated in the fitting housing. The backflow preventer 64 is basically similar in structure to the upstream backflow preventer 40 and therefore not described in detail. Both backflow preventers 40 and 64 open only in the direction from the inlet pressure to the outlet pressure. Between the valve body 18 and the downstream backflow preventer 64, a medium-pressure space 66 is formed.

The coil spring 52 of the backflow preventer 40 is stronger than the coil spring 60 acting on the valve body 18. Therefore, the backflow preventer 40 opens only when the valve body 18 is moved to its downstream end position by the pressure difference between inlet pressure and the mean pressure prevailing in the medium-pressure space. In this way, when the passage to the outlet port with respect to the outlet 14 and the atmosphere is completed, the backflow preventer is pressed by the water pressure. The heating system is filled to an outlet pressure slightly below the inlet pressure.

2, the drain valve body 18 is shown in detail with the drain valve open. The upstream backflow preventer 40 is closed. There is no input pressure to the drain valve body 18. The spring 60 is relaxed. In this state, the drain valve body is in a stopper position at a distance from the seat seal 32.

In Figure 3, the situation is shown, in which the inlet pressure in the inlet of the valve body increases. Then, the drain valve body 18 moves against the spring force of the spring 60 to the right in Fig.3. In this case, the valve body 30 abuts against the seat seal 32 in its end position. With the lateral surface 30 of the valve body 18 covers the drain 20. There is no water drain.

The discharge valve body 18 has a diameter on the input side, which is designated by "D" in FIG. The diameter corresponds to the inner diameter of the tubular fitting housing 10. The drain valve body 18 further forms an annular step 70, so that the downstream side has a smaller diameter. This smaller diameter is designated by "d" in FIG.

The inlet pressure thus acts on a surface which is determined by the diameter D. The seat seal 32 and the downstream side of the drain valve body 18, however, have a smaller diameter.

In the area 72 of the smaller diameter of the discharge valve body, an annular cavity 74 is formed between the discharge valve body and the inside of the fitting housing 10. In the cavity 74, a sliding seat 76 is guided. The sliding seat 76 has an L-shaped cross-section with legs 78 and 80. The sliding seat 76 is movably guided in the axial direction. Furthermore, a sealing ring 82 is provided in the cavity 74. Via a channel 82, the cavity 74 is hydraulically connected to the medium-pressure chamber. In the area in which the drain valve body 18 has a reduced diameter, a seal 88 is provided between the step 70 and the slide seat 76.

The medium pressure prevailing in the medium-pressure chamber 66 is also present in the cavity 74. With the drain valve 34 open, as shown in FIG. 2, the mean pressure corresponds to the atmospheric pressure. When the bleed valve 34 is closed, the medium pressure increases with increasing inlet pressure. This situation is shown in FIG. The sliding seat 76 moves to the right in the illustration.

In Figure 4, the situation is shown at high inlet pressure with open backflow preventer. The drain valve body 18 is against the spring force of the spring 60 in its right stop position. The drain valve is closed. The backflow preventer is opened. The medium pressure is also in the cavity 74. Due to this medium pressure, the sliding seat 76 is brought to the leg 78 against an annular shoulder in the valve body to stop. The pressure in the However, cavity 74 is also exerted on the rear, protruding part of the pressure surface of the valve body 18. This ensures that the effective area for the medium pressure is the same as for the inlet pressure. As a result, the forces on the valve body 18 remain independent of the inlet pressure.

In the described arrangement, the valve seat seal 32 has a reduced diameter. Since the forces on the valve body remain unchanged under unchanged pressure conditions, the contact pressure on the seat seal 32 but larger. This increases the sealing force.

Claims (8)

A system separator for physically separating an upstream fluid system from a downstream fluid system by means of a drain valve (34) in response to the pressure differential between upstream and downstream fluid systems, comprising an upstream backflow preventer (40), a downstream backflow preventer (64), and a dump valve body (18) formed as a piston. upstream of the upstream backflow preventer (40), an inlet pressure of the upstream liquid system, between the drain valve body (18) and the downstream backflow preventer (64), a mean pressure in a medium pressure space (66). and downstream of the downstream backflow preventer (64) is an outlet pressure of the downstream liquid system, and wherein at the bleed valve body (18), the pressure difference between Ei counteracts the inlet pressure and medium pressure in the closing direction of a loading spring (60) acting in the opening direction on the Ablaßventilkörper, the Ablaßventilkörper (18) on the downstream side has a reduced area (d), which is smaller than the effective pressure for the input pressure surface, thereby a cavity (74) is formed in the drain valve body, and the cavity communicates with the medium pressure space (66),
characterized in that
a sliding seat (76) movable in the direction of movement of the discharge valve body is provided in the cavity (74) facing the discharge valve body up to a housing-fixed stop (84) is movable, which is arranged in the flow direction in front of the valve seat (32) of the drain valve (34). System separator according to claim 1, characterized in that the outlet-side diameter of the Ablassventilkörpers is smaller than the inlet-side diameter and the sliding seat is formed by an annular sleeve which is movably guided in the cavity formed by the difference in diameter between Ablassventilkörper and housing. System separator according to claim 2, characterized in that the housing-fixed stop is formed by an annular step in the housing interior. System separator according to claim 3, characterized in that the annular sleeve has an L-shaped cross-section, one leg of which comes into contact with the inside when exposed to medium pressure at the stop. System separator according to one of the preceding claims, characterized by a channel for connecting the interior of the drain valve body with the cavity, which is formed in the region between the housing, the drain valve body and the sliding seat. System separator according to claim 5, characterized in that the channel from the cavity initially extends radially inwardly and then in the axial direction downstream of the medium-pressure space. System separator according to claim 5 or 6, characterized by a first seal, which is arranged in an annular groove on the outside in the drain valve body in the region of larger diameter and a second seal, which is arranged in the cavity between the channel and the movable sliding seat. System separator according to one of the preceding claims, characterized in that the backflow preventer, the drain valve body, the loading spring, the housing and the sliding seat are arranged coaxially.

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