Wells – Screens – Concentric pipes
Reexamination Certificate
2001-03-19
2003-06-24
Bagnell, David (Department: 3672)
Wells
Screens
Concentric pipes
C166S228000
Reexamination Certificate
active
06581683
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of water well filters.
2. Description of Prior Art
In certain geographical areas, aquifer layers containing water exist beneath the surface layers of the earth. Wells may be provided to access the aquifer layers and a filtering device may be inserted into the well to extract and filter the water in the aquifer layers. Water from the aquifer layers naturally contain a substantial amount of particulate matter. Such water when satisfactorily filtered and extracted can be used for a number of beneficial purposes.
Screened metal pipes have been used to filter water in wells. Metal pipes, however, tend to be heavy which presents a problem for workers who have to manually insert and lower the pipes into the wells. Metal pipes also deteriorate quickly in the water well environment, which can lead to weakness in the vertical pipe column. As a result of prolonged contact with water, detritus may develop and cause the metal to rust, allowing bacteria to develop and contaminate the water.
Screened plastic pipes have also been used to filter water in wells. However, both plastic and metal filters consist of pipes attached end to end to form a single conduit having only a single wall between the exterior and the interior of the conduit. Thus, the single-walled filters tend to allow particulate matter in the water which are smaller than the size of the screen to pass through into the water distribution system inside the filter.
Significant water flow into the pipe is important since the water will have to be moved up along the pipe. Typically, this is accomplished with a pump disposed inside and at the bottom of the pipe. If insufficient water flows into the pipe, the pump will be unable to move the water up along the pipe to its intended destination. To increase water flow, more screens can be formed into the pipes. However, increasing the number of screens or casings adds further weight to the total pipe column. The weight of the column may cause certain pipes, such as plastic pipes, to break as the tensile strength capability of the pipe is exceeded. Thus, adding more screens weakens the pipe and decreases its longevity. While increasing the thickness of the pipe wall might slightly increase its tensile strength capability, it reduces the cross-sectional area of the pipe's passageway, thereby reducing flow. Furthermore, increasing the wall thickness also adds weight which increases difficulties in handling such a pipe. At a given depth, the increased weight of the pipe will exceed the pipe's tensile strength, causing the pipe to break.
In addition, as the depth of a well increases, the temperature of water found inside the well also increases.
BRIEF SUMMARY OF THE INVENTION
The invention is a water well filter. An outer pipe is concentric with an inner pipe. The outer pipe has an outer plurality of water passage apertures, or slots, while the inner pipe has an inner plurality of water passage apertures, or slots. Both the inner and outer plurality of water passage apertures extend from an outer surface to an inner surface of their respective pipe. The outer pipe has a length that is shorter than that of the inner pipe, but long enough to cover the entire inner plurality of water passage apertures. The inner pipe has an internally threaded portion at either the upper or lower end, and an externally threaded portion at an opposite end. Therefore, the upper end of the inner pipe may be attached to the lower end of another inner pipe of another water well filter, or at least the lower end of another pipe. The outer pipe is attached to non-apertured portions of the inner pipe by upper and lower sealing rings disposed at upper and lower ends of the outer pipe, respectively. The outer pipe is attached to the inner pipe so as to form an annular gap between the outer surface of the inner pipe and the inner surface of the outer pipe.
A permeable, granulated filter material fills the gap. Thus, the sealing rings serve to close the gap and seal the granulated filter material. The granulated filter material may include a bonding mechanism so that the filter granules are bonded together. The filter granules may also be bonded to the outer surface of the inner pipe and the inner surface of the outer pipe. A permeable cover comprising nylon mesh is disposed on the outer surface of the inner pipe. The permeable cover has openings with an opening cross-dimension less than the granule cross-dimension of the filter granules so that the filter granules cannot reach the inner plurality of water passage apertures.
The outer pipe, inner pipe, sealing rings and granulated filter material all comprise unplasticized polyvinyl chloride (“UPVC”). Therefore, the sealing rings may be welded onto the outer and inner pipes.
The invention also comprises a method for filtering out particulate matter from water in a well, the method comprising: passing the water through a first plurality of apertures in a first barrier; blocking an initial portion of the particulate matter with the first barrier; passing the water through filter granules; blocking a first intermediate portion of the particulate matter with filter granules; passing the water through a second plurality of apertures in a second barrier; and blocking a final portion of the particulate matter with the second barrier. The method may further comprise: disposing a permeable cover with a plurality of openings onto the second barrier; passing the water through the plurality of openings in the cover; and blocking a second intermediate portion of the particulate matter with the cover.
A conduit is provided for filtering water in a well. The conduit comprises an inner layer comprising a first plurality of polymers, a middle layer comprising a second plurality of polymers, an outer layer comprising a third plurality of polymers, slots defined in the inner layer, middle layer, and outer layer, a first end portion, and a second end portion opposite to the first end portion and adapted to mate with the first end portion.
The inner layer, middle layer and outer layer each comprise acrylic butadiene styrene and unplasticized polyvinyl chloride. The middle layer comprises a greater proportion of acrylic butadiene styrene than the inner layer and the outer layer. In a preferred embodiment, the inner layer and outer layer each comprise 10% to 20% acrylic butadiene styrene and 80% to 90% unplasticized polyvinyl chloride whereas the middle layer comprises 20% to 50% acrylic butadiene styrene and 50% to 80% unplasticized polyvinyl chloride. The middle layer has a thickness greater than a thickness of the inner layer and a thickness of the outer layer.
The first end portion comprises an externally threaded portion. The second end portion comprises an internally threaded portion. The externally threaded portion and the internally threaded portion are molded. The conduit further comprises a shoulder adjacent to the externally threaded portion. The slots are arranged into groupings, each grouping comprising an array of slots spaced closely together, each grouping spaced apart from the other.
In another aspect, a dual conduit filter apparatus is provided for use in a water well. The apparatus comprises an inner conduit, an outer conduit and filter granules disposed in a gap between the conduits. The inner conduit has a first inner layer, a first middle layer, and a first outer layer, a plurality of inner conduit slots, a first end portion, and a second end portion opposite to the first end portion and adapted to mate with the first end portion. The first inner layer, first middle layer and first outer layer each comprise a plurality of polymers. The first inner layer, first middle layer and the first outer layer each comprise acrylic butadiene styrene and unplasticized polyvinyl chloride. The first end portion comprises an externally threaded portion. The second end portion comprises an internally threaded portion. The externally threaded portion and the internally threaded portion are mo
Bagnell David
Dougherty Jennifer R.
Lin, Esq. Vic Y.
Myers Dawes Andras & Sherman
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