Liquid purification or separation – Diverse distinct separators – Including a filter
Reexamination Certificate
2000-02-08
2001-05-15
Simmons, David A. (Department: 1724)
Liquid purification or separation
Diverse distinct separators
Including a filter
C210S393000, C210S416100, C210S532200
Reexamination Certificate
active
06231764
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to systems for pumping effluent out of septic tanks.
BACKGROUND OF THE INVENTION
Certain wastes introduced into a septic tank tend to separate into distinct layers: a bottom sludge layer, a top scum layer, and a noticeably distinct intermediate liquid layer that is to a large extent free of scum and sludge. U.S. Pat. No. 5,531,894 describes a septic tank and a system for pumping effluent out of the tank. An electricmotor-operated effluent pump is disposed generally upright and coaxially within an upright main tube that extends downward from a top wall of the tank to a location at or near a bottom wall of the tank. Hence, the tube will pass through the top scum layer, through the intermediate liquid layer, and into the bottom sludge layer. Operation of the pump is controlled by sensors that sense the level of waste in the tank. When the level rises beyond an upper limit, the pump operates to pump fluid out of the tank until the level drops to a lower limit at which the pump shuts off.
Because of the nature of certain electric-motor-operated effluent pumps, it is important that liquid flows along the exterior of the pump/motor when the motor operates the pump so that heat generated by the electric motor is transferred to the liquid. Hence, a known electric-motor-operated pump for a septic tank comprises a tubular sleeve within which the pump and motor are coaxially disposed, and it is this sleeve that is disposed coaxially within the aforementioned upright main tube that extends downward from the top wall of the tank.
For various reasons, it is desirable to maintain the waste level within the tank between the upper and lower limits by pumping liquid from the intermediate zone, rather than drawing from either the sludge or scum layers. Accordingly, it is known to provide openings through the side wall of the main tube at the intermediate layer so that liquid from that layer can enter the main tube and pass downward through the main tube to the bottom of the pump/motor sleeve where it can then be drawn upward through the sleeve by operation of the pump. As the pump operates, liquid is drawn upward across the exterior of the electric motor that operates the pump and enters the pump inlet. The pump pumps the liquid out through an effluent pipe connected to the pump outlet, thereby conveying the effluent out of the tank. The liquid passing along the exterior of the motor serves to provide some cooling of the motor.
Because the intermediate layer may contain materials that are other than pumpable liquid, the intermediate layer liquid is filtered before it reaches the pump. It is known to use stationary screens for such filtering, as shown by the aforementioned and other U.S. Patents such as U.S. Pat. Nos. 5,635,064 and 5,492,635.
SUMMARY OF THE INVENTION
The present invention relates to a novel system and device for pumping effluent from a septic tank, including a rotary self-cleaning strainer for filtering non-liquid materials from the intermediate waste layer of a septic tank. The present invention utilizes certain principles of the commonly owned U.S. Pat. No. 5,215,656, the entire disclosure of which is incorporated herein by reference.
Several embodiments of the invention are disclosed, and each possesses certain unique features within the generic scope of the invention. The various embodiments possess various constructional and functional attributes endowing them with certain advantages. Certain tubes may be conventional PVC plastic which is readily available, and may be cut to desired lengths at an installation site. The strainers use materials that are suited to provide long service life. Should service be needed, the system, and various parts may be conveniently removed and/or disassembled.
A general aspect of the invention relates to a system for pumping effluent from a septic tank comprising a tube having an open end adapted to be disposed upright within a septic tank so that effluent can enter the tube. A strainer strains effluent entering the tube, and includes a cylindrical filter screen disposed coaxial with the tube to separate a cylindrical interior of the strainer circumscribed by the filter screen from an exterior surrounding the interior and constrain flow of effluent through the strainer to pass radially through the filter screen. An electric pump unit is disposed coaxially within the tube and comprises an inlet port which, along the direction of effluent flow through the system, is disposed downstream of the strainer and through which effluent enters the pump unit, and an outlet port at which effluent pumped by the pump unit exits the pump unit. An outlet pipe is communicated to the pump unit outlet port and conveys effluent pumped by the pump unit is conveyed out of the septic tank. A nozzle communicated to the pump unit outlet port is arranged to emit effluent pumped by the pump unit in a direction toward the cylindrical filter screen opposite the effluent flow through the filter screen so as to cause the filter screen to be acted upon by both radial and circumferential flow components. A journal mounts one of the screen and the nozzle for rotation relative to the other such that effluent emitted from the nozzle is effective both to turn the screen and nozzle relative to each other and to dislodge debris from the filter screen.
In certain embodiments the journal journals the screen for turning, and the nozzle is stationary while in others, the nozzle is journaled for turning and the screen is stationary.
In some embodiments, the nozzle is disposed within the interior of the strainer and arranged to emit effluent in a radially outward direction, and the flow of effluent through the filter screen is radially inward toward the interior of the strainer. In others, the nozzle is disposed in the exterior of the strainer and arranged to direct effluent radially inward toward the interior of the strainer, and the flow of effluent through the filter screen is radially outward toward the exterior of the strainer.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which are accompanied by drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.
REFERENCES:
patent: 3443696 (1969-05-01), Schutte
patent: 5215656 (1993-06-01), Stoneburner
patent: 5492635 (1996-02-01), Ball
patent: 5531894 (1996-07-01), Ball et al.
patent: 5635064 (1997-06-01), Bovington
patent: 5690824 (1997-11-01), Stuth
patent: 5904847 (1999-05-01), Bovington
patent: 5985139 (1999-11-01), Zoeller
Boller George L.
Lawrence Frank M.
Perfection Sprinkler Co.
Simmons David A.
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