Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
1999-11-03
2001-04-24
Rivell, John (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S527800, C137S315110, C137S454200
Reexamination Certificate
active
06220282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains generally to devices, assemblies and systems for backflow prevention. More particularly, the present invention pertains to a compact, light weight, low maintenance double check valve backflow prevention apparatus of modular construction which is easily assembled and disassembled, which does not require a side port extension or flange, and which does not require a separate cover or lid for a side port.
2. Description of the Background Art
Backflow prevention devices are widely used to prevent undesirable flow reversal under low flow, static or backpressure situations wherein clean upstream fluid sources can be contaminated by downstream fluid. Backflow prevention devices typically comprise one or two check valves, housed within a valve body, which undergo closure under backflow, backpressure or back siphonage conditions. The use of backflow prevention devices is generally required by law for cross-connected water supplies where potable water could undergo contamination due to flow reversal or back pressure conditions.
Currently used double check valve backflow preventers have proved deficient in various respects. Particularly, such back flow preventers are prone to relatively high flow losses due to the valve configurations and closure mechanisms employed, especially under low flow conditions. Further, back flow preventer assemblies typically require a bulky, heavy cast housing with a side port tube or extension and a separately cast port cover. This type of housing is expensive to manufacture and requires a substantial amount of space to accommodate the side port tube and cover. The check valves are typically bolted to seats within the housing, and can only be reached through the side port tube, which hinders access to the check valves. Maintenance and replacement of the check valves requires a person to reach through the side port tube and loosen bolts, compression rods or other internal hardware in order to remove the check valves, and thus tends to be a difficult and expensive operation.
Accordingly, there is a need for a backflow prevention apparatus which is compact and light weight, which is easy and inexpensive to manufacture, which does not have a side port tube, and which provides easy access to internal check valves. The present invention satisfies these needs, as well as others, and generally overcomes the deficiencies found in the background art.
SUMMARY OF THE INVENTION
The invention is a double check valve backflow prevention apparatus of lightweight, compact, modular construction which eliminates the bulky side port and cover of conventional check valve assemblies. In general terms, the invention comprises a primary housing component having a lateral opening, a first check valve module which fits within the lateral opening a second check valve module which also fits within the lateral opening a central housing component, said central housing fitting within the lateral opening between the first check valve module and second check valve module, a first seal means for maintaining a fluid tight seal positioned between the first check valve module and central housing component, and a second seal means for maintaining a watertight seal positioned between the second check valve module and central housing component, with the primary housing component, first and second check valve modules and central housing component defining a complete, fluid-tight valve body or assembly.
By way of example, and not of limitation, the first and second check valve modules each preferably include an outer housing section, portion or wall, with the housing sections being generally structured and configured to fit adjacent the edges of the lateral opening in the primary housing component. The outer housing sections may be detachable from the check valve assemblies. The central housing component also includes an outer housing section, and is structured and configured to fit between the housing sections on the first and second check valve modules. A conventional check valve assembly is also associated with each of the check valve modules. The assembled primary housing component, check valve modules and central housing component define a complete, fluid-tight valve body which can be incorporated directly into a fluid flow system. Preferably, the lateral opening in the primary housing component is flangeless, so that the assembled primary housing component, check valve modules and central housing component provide a smooth, compact, cylindrical valve body with no lateral extensions or protrusions.
Preferably, a third seal means for maintaining a fluid tight seal is positioned between the first check valve module and the primary housing component, and a fourth seal means for maintaining a fluid tight seal is positioned between the second check valve module and the primary housing component.
The apparatus of the invention is assembled by placing the upstream and downstream check valve modules into the lateral opening of the main housing component, and respectively positioning the upstream and downstream check valve modules so that the housing sections on the modules are respectively adjacent the upstream and downstream edges of the lateral opening. The check valve modules are structured and configured such that, once positioned adjacent the upstream and downstream edges of the lateral opening, the check valves are properly located within the main housing component in generally the center of the flow stream. The central housing component or module is then placed within the lateral opening between the upstream and downstream check valve modules. The central housing module is held in place by a single bolt which extends laterally through the main housing component and into the central housing module.
The central housing module, check valve modules and main housing component are structured and configured such that, when assembled, each component or module is held securely in place by the adjacent component or module. The central module and check valve modules may additionally be secured together by a bolt. The central housing component and the housing sections on the upstream and downstream check valve modules effectively cover or fill the lateral opening and define a part of the overall housing or body of the apparatus. The seal means are preferably provided by o-rings or other elastomeric seals positioned between the central housing component the check valve modules, and between the check valve modules and the primary housing component or body so that the assembled structure is fluid-tight. The modular nature of the apparatus of the invention allows for small, light weight construction and easy manufacture and assembly, and provides a compact, portless valve body when fully assembled.
The check valve modules are held in position with respect to the main housing component by the interposed central housing component, and additional hardware is not needed to hold the check valves in place in the main housing body. In order to repair or replace the check valves, one need only unfasten and remove the central housing component from the main housing component in order to remove or access the check valve modules. Since the lateral opening does not have a side extension or flange, the check valves are easier to reach than in conventional double check valve backflow prevention devices. Also, since the check valve modules are held in place by the central housing component itself, no further disassembly is need to detach and remove the check valves. The present invention thus eliminates the difficulty of accessing check valves through a side port extension which occurs in conventional, previously available backflow prevention devices.
An object of the invention is to provide a backflow prevention apparatus which is compact and light weight.
Another object of the invention is to provide a backflow prevention apparatus which is easy and inexpensive to manufacture.
Another object of the invention is to provide a backflow prevent
Hunter Innovations, Inc.
Rivell John
Sierra Patent Group Ltd.
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