Backflow Preventer
A reduced pressure zone backflow preventer comprising a body 12 entirely made of plastic material, formed with an inlet port (14) accommodating an inlet check valve assembly 120 and an outlet port accommodating an outlet check valve assembly 122. The check valve assemblies extend along a coaxial axis coinciding with a longitudinal axis of the body. A central space 60 formed between the check valves is accessible through a service opening in the body. A relief valve assembly 70 is received within the central space and a drain port extends from the space. The relief assembly is responsive to pressure differential between the inlet port and the space by a flow passage extending between the inlet port and an upper side of a pressure diaphragm of the relief valve assembly.
The present invention relates to fluid backflow preventers and more particularly it is concerned with Reduced Pressure Zone backflow preventers, often referred to as RPZ. Even more specifically, the present invention is concerned with structural features of an RPZ.
BACKGROUND OF THE INVENTIONBackflow preventers are well known and are typically used for allowing flow of water (or other fluid) from a source (such as a municipal water supply) to an end user (consumer). A backflow preventer is used to prevent flow of the fluid (e.g. water) in the reverse direction (e.g., for avoiding contamination of a municipal potable water supply, by contaminated water, chemicals, fertilizers, and pesticides and the like which may be supplied through an automatic dosing device, etc.). Such systems are often obligatory under different municipal and other codes and requirements.
A number of configurations are known in the art for avoiding backflow including vacuum breaker systems, Reduced Pressure Zone backflow preventers—RPZs, and double check valve systems. In a double check valve system, the fluid, in normal use, flows through a first check valve, into a zone between the two check valves and then flows through a second check valve. The check valves are of either a normally closed or a normally open type, depending on the configuration of the device. Further provided there is a relief valve in flow communication with the zone for discharge of water (or other fluid), in case of reverse flow, due to change in the pressure system and malfunction of the device. Such a relief valve is of either a normally closed or a normally open type, depending on the configuration of the device.
During normal use, the zone is maintained at a pressure lower than the inlet pressure. If there is a pressure at the outlet port which is not at least a predetermined amount lower than the pressure at the inlet port, the check valves will close, thus preventing backflow. According to another arrangement, the first and second check valves are normally closed and displace into their respective open position under fluid pressure.
If abnormal conditions arise, in which there is no flow, or reverse flow, and the second check valve is in a failed state (e.g. is arrested in an open/closed position), the differential release valve will open and discharge liquid to the environment, so as to avoid backflow to the source supply.
Backflow preventer valves must often withstand high pressures (such as about 150 psi or more), thus requiring the use of a massive and reinforced body structure.
In some prior art backflow preventers the inlet and outlet ports are non-parallel and/or non-coaxial and/or provide flow in opposite directions with respect to one another resulting in the need for additional fittings for installation in a so called ‘in-line’ installation (which is common in point-of-use applications), undesirably adding to the cost of design, installation, maintenance and the like, as well as potentially increasing the size or volume of the device as installed.
Some prior art backflow preventers are configured such that servicing and maintenance is performed through different openings of the body of the device. Such configurations are believed to be inconvenient in many situations, in particular at point-of-use installations, where the available space for accommodating access to the device is restricted.
In several prior art backflow prevention devices, at least some of the components are received within a separate or enclosure, thus requiring installation of bolts through flanges or other coupling devices in order to achieve the desired total assembly. Such coupling devices typically add to the volume, length and/or weight of the total assembly, as well as to the general labor and costs involved.
Furthermore, many backflow preventers require for installation or removal of some or all components special tools and devices which generally require hand and/or power tools (wrenches, screwdrivers, nut-drivers etc. and in some lo cases specially designed tools), typically involving inserting or removing bolts, nuts, screws and the like.
This necessarily leads to relatively high costs of fabrication, assembly, maintenance and repair, and is further not suitable at tight space installations, as mentioned hereinabove. Prior art preventer backflow devices are disclosed, for example, in the following list of U.S. Pat. Nos. 4,489,746, 6,021,805, 6,346,736, 6,513,543, 6,546,946, and further in Patent Applications US 2002/0062868A1, EP 0964104A2 and WO 02/21029A1.
It is an object of the present invention to provide a reduced pressure zone backflow prevention device in which substantially all components, at least the first and second check valves and the relief valve, are enclosed within a single housing without the need for a coupling device and are easily accessibly, wherein a plurality of its components, and in particular both check valves, can be accessed for repair or maintenance from a single location.
It is a further object of the invention to provide a backflow prevention device with minimal components and where hardly any tools are required for fabrication, assembly, servicing, and maintenance.
It is still an object of the invention to provide a backflow prevention device with inlet and outlet openings which are parallel, and still preferably coaxial with on another and defining flow in the same direction with respect to one another.
According to the present invention there is provided a reduced pressure zone backflow preventer, herein the specification and claims referred to in short as an ‘RPZBP’ wherein the above disadvantages are substantially reduced or overcome and where the above advantages are exploited.
SUMMARY OF THE INVENTIONA backflow prevention device according to the present invention offers the above features and other objects which are achieved by an assembly wherein significant components thereof are made of elastomeric materials.
Accordingly, the invention calls for a reduced pressure zone backflow preventer (RPZBP) comprising a body made of plastic material formed with an inlet port accommodating an inlet check valve assembly and an outlet port accommodating an outlet check valve assembly, said check valves extending along a coaxial axis coinciding with a longitudinal axis of the body, and a central space formed between said check valves accessible through an opening, with a relief valve assembly received within the central space and a drain port extending from said space; said relief assembly is responsive to pressure differential between the inlet port and the space by a flow passage extending between the inlet port and upper side of a pressure diaphragm of the relief valve assembly.
The space further accommodates a retention member fixedly receivable within the space and extending between the check valves so as to bear axial loads applied by said check valves, though without transferring axial loads between said check valves.
The structure of the RPZBP is such that the inlet check valve assembly, the outlet check valve assembly, the relief valve assembly and the retention member are slidingly introduced through the service opening and are retained at their respective locations without the need for any fixtures such as screws and bolts, etc. important note is made to the fact that the body is a uniform solid structure made of plastic material, optionally of composite material for reinforcement thereof.
The central space within the body has a longitudinal axis intersecting the longitudinal axis of the body at an essentially right angle. Typically, the body assumes a shape of two cylindrical bodies intersected at a right angle.
The RPZBP according to the present invention has many unique features which are possible owing to the structure thereof, stating for example the following:
-
- Both the inlet check valve assembly and the outlet check valve assembly are modular, easy replaceable and designed for foolproof assembly so as to prevent reverse assembly;
- Essentially no tools are required for assembly/disassembly and servicing of the device, apart for a tool for opening the service opening, such as a screwdriver;
- The entire device, apart for some screws and springs is made of molded (injected) plastic material, optionally reinforced by composite material technology;
- Several test cocks are provide for calibration and testing, as may be required under different codes and standards;
- In the inadvertent case of failure of the inlet check valve, even if the piston stem is arrested at a position projecting into the space, the retention member can nevertheless be removed from the space for servicing;
- The retention member is biased in its location within the space by a spring of the relief valve assembly, whilst the retention member supports and guides the spring and stem member.
In order to understand the invention and to see how it may be carried out in practice, an embodiment will now be described, by way of a non-limiting example only, with reference to the accompanying drawings, in which:
FIGS. 4 are directed to the inlet check valve assembly, wherein:
Attention is first directed to
The body 12 further comprises an upright extending cylindrical portion 18 extending at a right angle with respect to the longitudinal axis of the body 12 and formed with an opening (29 in
Three test cocks 28A (being in flow communication with the inlet port through aperture 59; see
Clear indications in the form of arrows 32A, 32B, 32C and 32D are marked at various locations of the housing to provide correct guidance for direction of installation of the device.
With further reference made now also to
The end pieces 40 (see also
As can further be seen (best in
Received within the central space 60 is a relief valve assembly generally designated 70 (
Mounted on stem 78 there is a coiled spring 102 which at the assembled position is supported at its upper end by an annular support wall 106 of the lower disc 76 and bearing at its lower end over an annular support portion 110 of the retention member 68 (
As can best be seen in
Introduced through the space 60 and snugly received within the housing 12 there is an inlet check valve assembly 120 and an outlet check valve assembly 122, the structure and operation thereof will be explained in detail with reference to
It is appreciated that insertion and extraction of the inlet check valve assembly 120 and the outlet check valve assembly 122 obviates the use of any tools as these assemblies are merely introduced through the central space 60 (prior to introducing the retention member 68) whilst extraction thereof is facilitated either by pushing each check valve assembly through its respective port towards the central space 60 or by a leverage tool (any available tool) applying force on the tabbed wall portion 130 and 132, respectively.
Turning now to
As already mentioned, the check valve assemblies are in the form of cylindrical capsules 140; 140′, with their facing ends (i.e. ends facing the central space 60 within the body) formed with a projecting tab 130; 132. In accordance with a typical embodiment, there is an inscription at said facing ends reading “inlet” and “outlet”, respectively. The arrangement is such that only upon correct and complete insertion of the inlet check valve assembly 120 and the outlet valve assembly 122, the retention member 68 may then be inserted and seated within the space 60, as will become apparent herein later with further reference to
The check valve assemblies slidingly accommodate a sphere-like piston body 150; 150′ fitted with a stem member 152; 152′ supporting a coiled spring 154; 154′ biasing the piston member into sealing engagement against a sealing seat surface 158; 158′ (position seen in
The assembly is packed into the housing 140; 140′ by a cover member 166; 166′ snappingly engaged with the housing 140 and fitted with a sleeve portion 168; 168′ (best seen in
The arrangement is such that in their normal position the inlet check valve assembly 120 is closed and will open only upon water pressure at its inlet side to facilitate flow in the predetermined position, i.e. from the inlet port 14 towards the central space 60, as indicated by the arrows in FIGS. 1 to 3, and the outlet check valve assembly 122 is normally closed and will facilitate water flow there-through only upon water pressure at the space 60 to allow water flow in the direction from the central space 60 towards the outlet port 16 as indicated.
Turning now to
Further noticed, the central path 180 of the retention member 18 has a conical cross-section (
Further noticed, the retention member 68 is fitted with two circumferential ribs 194 and 196, which ribs are not equally spaced from the respective ends of the retention member 68. This arrangement is deliberate and is to ensure that the retention member 68 is correctly introduced into the central space 60, whereby said ribs 194 and 196 are securely received within the corresponding grooves 66 and 64 formed in said substantial space 60. Furthermore, a pair of longitudinal ribs 200 extend between said circumferential ribs 194 and 196, serving both to strengthen the structure of the retention member 68 and further, to bear against the wall portions 63 in the central cavity 60 of the body 12, in the assembled position.
An arrow 197 marked on the retention member 68 indicates the flow direction through the device 10, so as to provide indications for correct and easy assembly.
When in the assembled position, top opening 184 of the retention member 68 and the bottom opening 186, axially coincide with the discharge outlet 86 of the housing 12 (
With further particular reference made to
The arrangement is such that at a normal position of the backflow preventer 10, when there is no water flow therethrough, both the inlet check valve assembly 120 and the outlet check valve assembly are at their normally closed position. At this state, backflow pressure applied to the outlet check valve assembly 122 (represented by arrow 130 in
When water pressure is applied at the inlet port 14 in direction of arrow 136 in
As can further be seen, for example in
It is further noted in
It is further seen, best in
The embodiment of
As further seen in
Attention is now directed to
While it has been shown an embodiment of the invention, it will be appreciated by a person of the art that many modifications and changes may be is made therein without departing from the spirit and the scope of the invention, mutatis mutandis.
Claims
1. A reduced pressure zone backflow preventer comprising a body formed with an inlet port accommodating an inlet check valve assembly and an outlet port accommodating an outlet check valve assembly, said check valve assemblies extending along a coaxial axis coinciding with a longitudinal axis of the body, a central space formed between said check valves accessible through a service opening in the body, a relief valve assembly received within the central space and a drain port extending from said space; said relief assembly is responsive to pressure differential between the inlet port and the space by a flow passage extending between the inlet port and an upper side of a pressure diaphragm of the relief valve assembly; and wherein the entire body is made of plastic material.
2. A backflow preventer according to claim 1, wherein the space accommodates a retention member fixedly receivable within the space and extending between the check valve assemblies so as to bear axial loads applied by said check valves, though without transferring axial loads between said check valve assemblies.
3. A backflow preventer according to claim 1, wherein the inlet check valve assembly, the outlet check valve assembly, the relief valve assembly and a retention member are slidingly introduced through the service opening.
4. A backflow preventer according to claim 1, wherein the inlet check valve assembly, the outlet check valve assembly, the relief valve assembly and a retention member are made of plastic material.
5. A backflow preventer according to claim 1, wherein the body is made of reinforced composite plastic material.
6. A backflow preventer according to claim 1, wherein the central space within the body has a longitudinal axis intersecting the longitudinal axis of the body at an essentially right angle.
7. A backflow preventer according to claim 1, wherein the body assumes a shape of two cylindrical bodies intersecting at a right angle.
8. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly are replaceable modular elements.
9. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly are designed for foolproof assembly so as to prevent reverse assembly thereof within the body.
10. A backflow preventer according to claim 1, wherein one or more test cocks are fitted to the body, each of which being in flow communication with a respective zone of the preventer and being selectively opened.
11. A backflow preventer according to claim 2, wherein the retention member can be removed withdrawn for servicing the preventer even if a piston stem of the inlet check assembly is arrested at a position projecting into the central space.
12. A backflow preventer according to claim 2, wherein the retention member is biased in its location within the central space by a spring of the relief valve assembly, whilst the retention member supports the spring and provide guidance for axial displacement of a stem member.
13. A backflow preventer according to claim 2, wherein one of the retention member and the body is formed with at least one radially projecting rib, asymmetrically extending along the longitudinal axis thereof, for engagement with a corresponding groove formed in the other one of the retention member and the body.
14. A backflow preventer according to claim 1, wherein the central space is fitted with a pair of parallel side walls.
15. A backflow preventer according to claim 14, wherein the side walls are interconnected at their bottom ends via an arced surface.
16. A backflow preventer according to claim 14, wherein the side walls constitute a double walled portion within the central space said parallel walls slidingly receive a retention member and reinforce the body.
17. A backflow preventer according to claim 1, wherein a cylindrical portion within the body receiving the inlet check valve assembly has a first diameter at a portion adjacent the central space which is slightly larger in diameter than an end portion thereof adjacent an inlet end.
18. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly differ from one another in the shape of their distinguishable outer casing.
19. A backflow preventer according to claim 1, wherein the central space is formed with a normally open discharge outlet, sealable by the relief valve assembly under liquid flow through the preventer.
20. A backflow preventer according to claim 19, wherein a plastic spout is attachable to the discharge outlet.
21. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly are each fitted with a retraction tab or grove to facilitate extraction thereof from the body.
22. A backflow preventer according to claim 1, wherein an inlet end and an outlet end of the body are fittable with a replaceable connecting member made of plastic material.
23. A backflow preventer according to claim 22, wherein the connecting member is fixable to the respective inlet end and an outlet end of the body by a bracing coupler clampingly bracing a flanged rim portion of the connecting member to the body.
24. A backflow-preventer according to claim 1, wherein the body is formed with a flow passage communicating between the inlet port and a control chamber of the relief valve assembly.
25. A backflow preventer according to claim 24, wherein the flow passage is in flow communication with a test cock of the preventer.
26. A backflow preventer according to claim 24, wherein the flow passage is formed by a bore extending from a flanged rim portion at an inlet end of the body, an opening of said bore being blocked by a plug.
27. A backflow preventer according to claim 26, wherein the plug is retained in place by forehead portion of a connecting member fixedly coupled to the body.
28. A backflow preventer according to claim 1, wherein all components of the preventer are fittable through the central space.
29. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly are modular assemblies each comprising a cylindrical capsule slidingly accommodate a sphere-like piston body fitted with a stem member supporting a coiled spring biasing the piston member into sealing engagement against a sealing seat surface thereof.
30. A backflow preventer according to claim 29, wherein the inlet check valve assembly and the outlet check valve assembly are packed by a cover member snappingly engaged to the cylindrical capsule.
31. A backflow preventer according to claim 1, wherein each of the body, the inlet check valve assembly, the outlet check valve assembly, and a retention member are formed with indicia corresponding to correct assembly and flow direction of the preventer.
32. A backflow preventer according to claim 1, wherein the relief valve assembly comprises a resilient diaphragm supported by rigid plastic disc with a stem member downwardly extending and supporting at its bottom end a sealing ring sealingly engageable with a discharge outlet of the body.
33. A backflow preventer according to claim 32, wherein sealing ring extends above a guiding portion sized so as to ensure smooth sliding within a tubular section at the discharge outlet.
34. A backflow preventer according to claim 32, wherein a coiled spring of the relief valve assembly bears at one end thereof against the rigid plastic disc and at an opposed end thereof against a seat of a retention member of the preventer.
35. A backflow preventer according to claim 1, wherein the inlet check valve assembly and the outlet check valve assembly comprise a piston body fitted with a sealing ring received in a circumferential grove of the piston body and retained by sealing ribs projecting between the seal ring and side walls of the groove in a watertight fashion.
36. A backflow preventer according to claim 35, wherein the sealing ribs are integral with the sealing ring.
37. A backflow preventer according to claim 35, wherein the sealing ribs are integral with walls of the groove.
38. A backflow preventer according to claim 1, devoid of any metal components apart for springs and screws.
Type: Application
Filed: Apr 7, 2005
Publication Date: Oct 18, 2007
Applicant: A.R.I. FLOW CONTROL ACCESSORIES AGRICULTURAL COOPE (D.N. Ramat Hagolan)
Inventors: Youval Katzman (Zichron Yaacov), Mordechai Kandanyan (D.N. Ramat Hagolan), Jacob Grinberg (Tel Aviv), Meir Shuval (D N Ramat Hagolan)
Application Number: 11/630,351
International Classification: E03C 1/10 (20060101);