System disconnector

Abstract

A system disconnector (10) for physically disconnecting an upstream liquid system from a downstream liquid system by means of an outlet valve (48) provided in a housing (16), the disconnecting being effected depending on the pressure drop between the upstream and the downstream liquid system, and wherein the housing (16) is provided with a bore (28) and an opening (26) in alignment with said bore (28), said opening adapted to be closed, includes a pressure reducer (66, 36) in the form of a cartridge provided in said bore (28), which is adapted to be removed in one piece from the housing (16). The system disconnector (10) is provided with an upstream backflow preventer (40), a downstream backflow preventer (42), and an outlet valve body in the form of a piston (44) biased by a spring, said outlet valve body disposed between said backflow preventers, wherein the pressure reducer cartridge (34, 36), the backflow preventers (40, 42), and the outlet valve body (44) are disposed in alignment inside the bore (28).

Description

TECHNICAL FIELD

The invention relates to a system disconnector for physically disconnecting an upstream liquid system from a downstream liquid system by means of an outlet valve which is provided in a housing and the disconnecting being effected depending on the pressure drop between the upstream and the downstream liquid system.

System disconnectors or pipe disconnectors serve the purpose to safely prevent the backflow of liquid from a downstream liquid system to an upstream liquid system. The upstream liquid system may be a drinking water system. The downstream liquid system may be, for example, a heating system. It must be prevented under all circumstances that contaminated water from the heating system flows back into the drinking water system when it is filled or re-filled, for example due to a pressure drop in the drinking water system for some reason. So called backflow preventers are known in the art. They are spring biased valves allowing a liquid flow only in one direction, i.e. from the upstream to the downstream system. Such backflow preventers, however, can leak. Therefore, it is not permitted, for example with drinking water and heating water, to separate the liquid systems only by backflow preventers. A physical separation of the liquid systems must be effected in such a way that, in the case of a defect between the systems, a connection to an outlet and the atmosphere is established.

Prior Art

System or pipe disconnectors comprise an upstream backflow preventer connected to the upstream liquid system and a downstream backflow preventer connected to the downstream system. A pressure controlled outlet valve is positioned between the backflow preventers, establishing the passage from the upstream liquid system to the downstream liquid system, so if there is a sufficient pressure difference between the two liquid systems, the liquid can flow only from the upstream to the downstream liquid system. If there is no such pressure difference, the outlet valve connects the space between the backflow preventers to the atmosphere and an outlet.

A system disconnector is, for example, described in DE 10 2005 031 422.8 or in DE 10 2005 049 110.3. In the disclosed assembly, the outlet valve is a piston adapted to be shifted in the casing of a fitting. This piston is provided with a central passage and an annular valve seat at its downstream end face, the valve seat axially abutting a fitting-fixed seat sealing. The passage establishes a connection closed to the atmosphere between the upstream and the downstream liquid system. The upstream backflow preventer is positioned in the passage. Thereby a pressure difference between the inlet pressure in the upstream liquid system and a medium pressure occurring in a medium pressure space between the piston and the downstream backflow preventer acts on the piston against a spring power in the opening direction. In order to achieve a flow towards the downstream system, this pressure difference must exceed a given level determined by the spring power.

If, for example, a heating system shall be filled from a drinking water system through the system disconnector, at first the piston of the outlet valve is pushed by the inlet pressure of the drinking water system into its operating position against the power of the spring acting thereon, where it interrupts the connection to the atmosphere and to the outlet and establishes a connection between the drinking water system and the heating system. The upstream and downstream backflow preventers are then pushed open. Drinking water flows into the heating system for filling or re-filling. The heating system is filled up to an outlet pressure which is lower than the inlet pressure. During normal operation the difference between the inlet pressure and the outlet pressure is determined by the pressure drop at the backflow preventers, i.e., by the power of the springs of the backflow preventers. According to the pressure drop at the upstream backflow preventer and the pressure drop at the downstream backflow preventer, the medium pressure is at a level therebetween. The pressure difference between the inlet pressure and the medium pressure must be larger than a threshold value determined by the spring power of the valve body of the outlet valve.

System disconnectors must be, depending on its application, of type “BA”. This means that they must be provided with test sockets allowing the testing of the pressure conditions. This is especially the case if particularly contaminated water must be separated from the drinking water supply.

The filling of heating systems is effected with an inlet pressure which is reduced according to the system disconnector which occurrs when an upstream shut-off valve is opened. Such an inlet pressure typically is in the range of 4 bar and corresponds to the pressure which is set at the drinking water supply by, for example, a pressure reducer for the building. There are applications where the filling or re-filling is desired with a small pressure. In such applications a pressure reducer can be disposed downstream of the system disconnector. The downstream pressure reducer is then adjusted to a lower pressure. Such a pressure reducer prevents water being fed after the desired heating system pressure is reached, i.e., when the filling or re-filling process is finished. The arrangement having a downstream pressure reducer requires a lot of space, and many components. Its production is, therefore, very expensive. The installation is also very time consuming.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a compact system disconnector of the above mentioned kind with an effective pressure control.

According to the invention, this object is achieved in that the housing is provided with a bore and an opening in alignment with said bore, said opening adapted to be closed, and in that a pressure reducer in the form of a cartridge is provided in said bore, which is adapted to be removed in one piece from the housing. In other words: the system disconnector and the pressure reducer assembly are disposed in the same bore. Thereby the assembly is particularly small. Only one component must be installed. The opening in the housing is opened in order to carry out necessary services and the components of the system disconnector and the pressure reducer cartridge are readily accessible.

Preferably the system disconnector is provided with an upstream backflow preventer, a downstream backflow preventer and an outlet valve body in the form of a piston biased by a spring, said outlet valve body disposed between said backflow preventers and wherein the pressure reducer cartridge, the backflow preveters, and the outlet valve body are disposed in alignment inside the bore. Thereby a particulary small, coaxial assembly is achieved. All components can be accessed through the same opening in the housing.

In an embodiment of the invention the the pressure reducer is provided with a valve seat body cooperating with a fixed valve disc, said valve seat body being adjustable by a lifting member exposed to the outlet pressure in the closing direction against the effect of a helical spring. The valve seat body with the valve seat forms the moveable portion. The valve disc is fixed. With an axial bore the valve seat body is slidably guided on a valve spindle which is connected to the valve disc. The outlet of the downstream backflow preventer extends to the axial bore in the valve spindle and the bore is connected to the space upstream of the valve seat. This means that the downstream backflow preventer is directly integrated in the pressure reducer cartridge.

In a particularly preferred embodiment of the invention the valve spindle is integrated in a cartridge housing which is adapted to be inserted into the bore up to a stop and the downstream backflow preventer is adapted to be inserted into the cartridge housing. Consequently, the valve spindle and the backflow preventer can be pulled out of the bore together with the cartridge housing. The valve spindle can be provided with a valve disc at its downstream end, said valve disc extending into the inner space of the pot-shaped valve seat body, the valve spindle having a thickened portion in a radial direction in the range of the inner space of the valve seat body, said thickened portion serving as a dog for removing the cartridge housing from the bore. The valve seat body is then also pulled out of the bore in the housing together with the cartridge housing.

Preferably, test sockets are provided enabling a pressure control at the inlet, at the outlet and in the medium pressure chamber between the backflow preventers of the system disconnector. Such BA-System disconnectors may also be used for the separation of particularly contaminated water.

Further modifications of the invention are subject matter of the subclaims. A preferred embodiment of the invention is described below in greater detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which show the best mode currently contemplated for carrying out the invention:

FIG. 1 is a perspective view of a system disconnector with a pressure reducer.

FIG. 2 shows the system disconnector of FIG. 1 with its inner parts in an exploded view.

FIG. 3 is a cross sectional view of the system disconnector with pressure reducer of FIG. 1 and FIG. 2.

FIGS. 4a & 4b show the valve seat body of the pressure reducer in greater detail.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows a type BA system disconnector which is generally denoted with numeral 10. The system disconnector 10 is provided with an inlet 12 and an outlet 14. Upon its installation the inlet 12 is connected to a water supply pipe (not shown). The device which must be filled, such as, for example, a heating system, is provided on the outlet side.

A housing, generally denoted with 16, is provided between the inlet 12 and the outlet 14. An outlet funnel 18 for an outlet valve described below is provided on the lower side of the housing. Three test sockets 20, 22 and 24, which can be shut-off, are provided on the upper side of the housing for testing pressures.

The longitudinal axis of the housing 16 is not in alignment with the inlet 12 and the outlet 14, but forms an angle. This enables to provide an opening at the end of the housing which can be closed by a lid 26.

FIG. 2 shows an exploded view with the components provided inside a bore 28 in the housing. An outlet valve body 30 is provided on the inlet side. The outlet valve body is subjected to the spring power of a spring 32. If the lid 26 is opened, the spring 32 pushes the outlet valve body out of the bore together with the components described below which are connected thereto. Thereby, it is easily accessible. A cartridge housing 34 is shown behind the spring which, in an assembled state, surrounds the spring. The cartridge housing comprises a pressure reducer assembly. A valve seat body 36 belonging to the pressure reducer assembly can be removed from the bore 28 in the housing together with the cartridge housing 34. It can be seen that all components are inserted in alignment with the bore of the housing and can be removed. The cartridge housing 34 is designed in a way that it can be easily pulled out of the opening 28 with a suitable tool.

FIG. 3 shows a cross sectional view of the system disconnector 10 with an integrated pressure reducer. It can be seen that the test socket 20 is connected to the inlet 12. The test socket 24 is connected to the outlet 14. The test socket 22 is connected to the medium pressure chamber 38 of the system disconnector.

The medium pressure chamber 38 is provided between an upstream backflow preventer 40 and a downstream backflow preventer 42 (not shown in cross section). The upstream backflow preventer 40 is disposed inside an outlet valve body 44 similar to known system disconnectors. Together with the seat sealing 46, the outlet valve body forms the outlet valve 48. The outlet valve 48 operates with a compensation piston and sealing power amplification, as they are described in DE 10 2005 031 422.8 and DE 10 2005 049 110.3 and which are incorporated herein by reference. The backflow preventers 40 and 42 and the outlet valve 48 form a small system disconnector which is arranged in alignment with the bore 28 in the housing.

The seat sealing 46 of the outlet valve 48 is disposed in a shoulder 50 in the inner wall of the cartridge housing 34. The cartridge housing 34 is an elongated component engaging the outer wall at the inside of the bore 28 in the housing. It is sealed with sealing rings 54 and 56. The cartridge housing can be inserted into the bore 28 of the housing up to a stop 52.

The cartridge housing 34 forms an open collar 58 at its downstream end. A spring 60 is disposed inside this collar. The inside of the collar 58 defines a spring abutment for the spring 60. The spring 60 acts upon a two-portion valve seat body 36.

With its inside the pot-shaped valve seat body 36 is slidably guided on a valve spindle 62. The valve spindle 62 is provided with an axial bore 64. The valve spindle 62 is integrated in the cartridge housing 34 at the inner side of the collar. In such a way the spring 60 surrounds the valve spindle 62. On the inlet side, the downstream backflow preventer 42 is disposed in the widened end of the bore 64 in the valve spindle 62. A valve disc 66 with a sealing ring 70 is disposed on the outlet side end of the valve spindle 62. The sealing ring 70 is housed in a housing body 72 having a larger diameter than the valve spindle. The valve disc 66 closes or opens the opening 68, respectively, on the plane end of the valve seat body 36. A connection is established to the outlet 14 through an opening 68. The valve disc 66 and the valve seat body 36 form a pressure reducer valve.

A hollow space 74 is formed in the outlet side ranging between the valve spindle and the valve seat body. When the pressure reducer valve is opened, outlet pressure is present in this hollow space 74. A connection passage 76 connects the bore 64 in the valve spindle 62 with an annular space 78 in the casing of the valve seat body 36. FIG. 4 separately shows the valve seat body 36 with the connection passage. During the filling or re-filling process, an inlet pressure which is slightly reduced due to the system disconnector is present in the connection passage 76 and the annular space 78. If the outlet pressure is higher than the inlet pressure the valve seat body 36 is shifted towards the left side in FIG. 3 towards the valve disc against the spring power of the spring 60. The pressure reducer valve is then closed. If the outlet pressure in the outlet 14 drops, the spring and the inlet pressure will push the valve seat body 36 towards the right side in FIG. 3. The valve is open until the outlet pressure reaches the desired value.

The valve seat body 36 is made in two-portion form so that it can be mounted around the thickened end of the valve spindle 62. When it is pulled out, this end is caught in the valve seat body 36 and pulls it out of the bore 28 of the housing also.

Whereas the invention is here illustrated and described with reference to embodiments thereof presently contemplated as the best mode of carrying out the invention in actual practice, it is to be understood that various changes may be made in adapting the invention to different embodiments without departing from the broader inventive concepts disclosed herein and comprehended by the claims that follow.

Claims

1. A system disconnector (10) for physically disconnecting an upstream liquid system from a downstream liquid system by means of an outlet valve (48) provided in a housing (16) said disconnecting being effected depending on a pressure drop between said upstream and said downstream liquid system wherein said housing (16) is provided with an inlet (12), an outlet (14), a bore (28) and an opening (26) in alignment with said bore (28), said opening adapted to be closed and in that a pressure reducer (66, 36) in the form of a cartridge is provided in said bore (28), which is adapted to be removed in one piece from said housing (16).

2. A system disconnector (10) according to claim 1, wherein said system disconnector is provided with an upstream backflow preventer (40), a downstream backflow preventer (42) and an outlet valve body in the form of a piston (44) biased by a spring, and wherein said outlet valve body is disposed between said backflow preventers and wherein said pressure reducer cartridge (34, 36) said backflow preveters (40, 42) and said outlet valve body (44) are disposed in alignment inside said bore (28).

3. A system disconnector according to claim 2, wherein

(a) said pressure reducer is provided with a helical spring (60), a lifting member, a fixed valve disc (66) and a valve seat body (36) cooperating with said fixed valve disc (66) thereby defining a closing and an opening direction, said valve seat body being adjustable by said lifting member exposed to an outlet pressure in said closing direction against the effect of said helical spring (60),

(b) a valve spindle (62) is provided, said valve spindle having an axial bore (64); and wherein said valve seat body (36) is slidably guided on said valve spindle (62) connected to said valve disc (66) with an axial bore (64), and

(c) said outlet of said downstream backflow preventer (42) ends in said axial bore (64) in said valve spindle (62) and said bore (64) is connected to said space upstream of said valve seat.

4. A system disconnector (10) according to claim 3, wherein said valve spindle (10) is integrated in a cartridge housing (34) which is adapted to be inserted into said bore (28) up to a stop (52) and said downstream backflow preventer (42) is adapted to be inserted into said cartridge housing (34).

5. A system disconnector (10) according to claim 4, wherein said valve spindle (62) is provided with a valve disc (66) at its downstream end, said valve disc extending into an inner space of said pot-shaped valve seat body (36), and wherein said valve spindle (62) is provided with a thickened portion (72) in a radial direction in a range of said inner space (74) of said valve seat body (36), said thickened portion (36) serving as a dog for removing said cartridge housing (34) from said bore (28).

6. A system disconnector (10) according to claim 1, wherein test sockets (20, 22, 24) are provided enabling a pressure control at said inlet (12), at said outlet (14) and in said medium pressure chamber (38) between said backflow preventers (40, 42) of said system disconnector.