US3574509A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Backwash filter
Assignee: Zurn Industries LLC
•
Filing: 1969-02-14
•
Granted: 1971-04-13
•
Expires: 1989-02-14
Abstract
Abstract A filter for liquid and a control. The filter element is made up of two concentric perforated cylinders which restrain a very fine wire mesh between them, this assembly being supported in a hollow body. Liquid is fed into the inside of the filter element and flows to an outlet, by way of the perforations, through the mesh. The perforations form cavities which serve as reservoirs on the inside of the mesh. A backwash arm is rotated about an axis at the center of the filter element. The backwash arm has a slot defined by shaped members which sealingly sweep over the inner periphery of the filter element. Thus, debris which accumulates in the perforations is washed back through the slot in the arm and to a waste system by the impetus of the pressure on the downstream side of the filter element. The control is made to actuate the backwash arm at a rate of speed such that it will make a sweep around the inner periphery of the filter element only as required to clean the mesh and maintain flow. This is accomplished by a circuit that senses the fluid pressure drop across the filter. The motor which drives the backwash arm can be driven continuously or intermittently in response to this pressure drop to keep the cavities from filling with debris beyond a predetermined amount. A positive displacement device is connected to the outlet of the backwash arm, to meter the amount of backwash fluid. An interrupter is provided to stop this backwash device as the arm passes over unperforated spots in the filter element.
Inventors
- 👤 Ramon J Zentis
- 👤 John R Goode
- 👤 Donald F Durso
- 👤 John H Schmid
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:55
CPC Classifications
B; B01; B01D; B01D29/00; B01D29/11; B01D29/13; B01D29/23; B01D29/60; B01D29/606; B01D29/62; B01D29/66; B01D29/68; B01D29/682; B01D2201/00; B01D2201/04; B01D2201/0407; B01D2201/28; B01D2201/287
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
108 words
In combination, a backwash filter and a control for said backwash, said filter having an inlet and an outlet, a body and a filter element in said body in the flow path of liquid between said inlet and said outlet, a backwash element, means to move said backwash element over said filter element, said control comprising sensing means on said filter for sensing the pressure differential caused by debris accumulated on said filter element, said control means being adapted to control said backwash element whereby said backwash element backwashes said filter element at a rate proportional to the amount of said debris being accumulated on said filter element.
Claim 2
Dependent Claim
108 words
In combination, a backwash filter and a control for said backwash, said filter having an inlet and an outlet, a body and a filter element in said body in the flow path of liquid between said inlet and said outlet, a backwash element, means to move said backwash element over said filter element, said control comprising sensing means on said filter for sensing the pressure differential caused by debris accumulated on said filter element, said control means being adapted to control said backwash element whereby said backwash element backwashes said filter element at a rate proportional to the amount of said debris being accumulated on said filter element.
Claim 3
Dependent Claim
33 words
The combination recited in claim 1 wherein said sensing means comprises means to sense a pressure differential between the upstream side of said filter element and the downstream side of said filter element.
Claim 4
Dependent Claim
23 words
The combination recited in claim 1 wherein said filter element has openings therethrough having cavities at the upstream side of said filter element.
Claim 5
Dependent Claim
32 words
The combination recited in claim 1 wherein said means to move said backwash element comprises a variable speed motor, and means on said control unit to control the speed of said motor.
Claim 6
Dependent Claim
148 words
In combination, a backwash filter and control means for said backwash, said filter having a body having an inlet, an outlet, and a filter element in said body, a hollow backwash arm, drive means to provide relative motion of said backwash arm and said filter element, positiVe displacement means connected to said control means removing liquid through said arm at a predetermined rate, sensing means for sensing the pressure differential caused by debris on said element, said control means being connected to said displacement means and to said drive means, an adjustable control means sensitive to differential pressure across said filter element for controlling the speed of said backwash arm and said backwash flow control means, said sensing means being adapted to actuate said arm to remove said debris from said filter element at a rate determined by the rate of deposit of debris on said filter element.
Claim 7
Dependent Claim
148 words
In combination, a backwash filter and control means for said backwash, said filter having a body having an inlet, an outlet, and a filter element in said body, a hollow backwash arm, drive means to provide relative motion of said backwash arm and said filter element, positiVe displacement means connected to said control means removing liquid through said arm at a predetermined rate, sensing means for sensing the pressure differential caused by debris on said element, said control means being connected to said displacement means and to said drive means, an adjustable control means sensitive to differential pressure across said filter element for controlling the speed of said backwash arm and said backwash flow control means, said sensing means being adapted to actuate said arm to remove said debris from said filter element at a rate determined by the rate of deposit of debris on said filter element.
Claim 8
Dependent Claim
45 words
The combination recited in claim 5 wherein said control comprises transducer means for sensing and controlling the differential pressure between said outlet and said inlet, and tachometer means for sensing and controlling the speed of said drive means and the speed of said displacement means.
Claim 9
Dependent Claim
103 words
A filter and control therefor comprising a filter body having an inlet and an outlet with a filter element therebetween, said filter element having openings therethrough for liquid to flow from said inlet to said outlet, debris collecting cavities formed on the upstream side of said filter, backwash means, said backwash means supported on said filter body comprising a backwash member adapted for relative movement over said cavities on the upstream side thereof, and positive displacement means connected to said backwash means, said positive displacement means being adapted to remove the amount of material from said openings necessary to maintain predetermined flow conditions.
Claim 10
Dependent Claim
103 words
A filter and control therefor comprising a filter body having an inlet and an outlet with a filter element therebetween, said filter element having openings therethrough for liquid to flow from said inlet to said outlet, debris collecting cavities formed on the upstream side of said filter, backwash means, said backwash means supported on said filter body comprising a backwash member adapted for relative movement over said cavities on the upstream side thereof, and positive displacement means connected to said backwash means, said positive displacement means being adapted to remove the amount of material from said openings necessary to maintain predetermined flow conditions.
Claim 11
Dependent Claim
25 words
The filter recited in claim 7 wherein means is provided on said filter to move said backwash means over said filter at a controlled rate.
Claim 12
Dependent Claim
26 words
The filter recited in claim 8 wherein said control means comprises means sensitive to the pressure differential created by the debris accumulated in said enlarged portions.
Claim 13
Dependent Claim
38 words
The filter recited in claim 9 wherein said filter element has portions thereof which have no perforated portions, and means on said filter to deactuate said positive displacement means when said backwash means passes over said unperforated areas.
Claim 14
Dependent Claim
130 words
A filter and control comprising a filter body having an inlet and an outlet with a perforated filter element therebetween, a backwash arm supported on said filter body, variable speed motor means connected to said backwash arm to rotate said backwash arm to move a backwash arm over said filter element, backwash flow control means connected to said backwash arm, backwash motor means to drive said backwash flow control means, an adjustable control means sensitive to differential pressure across said filter element for controlling the speed of said backwash arm and said backwash flow control means. 12. The filter recited in claim 11 wherein means is provided on said control to shut off said backwash flow control means when said backwash element passes over dead spots in said filter element.
Claim 15
Dependent Claim
96 words
In combination, a backwash filter and a control comprising a filter element and scanning means, said scanning means having a low-pressure area and means to move said scanning means over the upstream surface of said filter element, and a metering device on the backwash outlet of said scanning means, said metering device being adapted to pass a controlled volume of fluid independently of the pressure on the metering device, and an adjustable control means sensitive to differential pressure across said filter element for controlling the speed of said backwash arm and said backwash flow control means.
Claim 16
Dependent Claim
96 words
In combination, a backwash filter and a control comprising a filter element and scanning means, said scanning means having a low-pressure area and means to move said scanning means over the upstream surface of said filter element, and a metering device on the backwash outlet of said scanning means, said metering device being adapted to pass a controlled volume of fluid independently of the pressure on the metering device, and an adjustable control means sensitive to differential pressure across said filter element for controlling the speed of said backwash arm and said backwash flow control means.
Claim 17
Dependent Claim
16 words
The combination recited in claim 13 wherein the backwash metering device is a positive displacement pump.
Claim 18
Dependent Claim
27 words
The combination recited in claim 14 wherein means is provided to control the speed of the metering device at a fixed ratio to the speed of scanning.
Claim 19
Dependent Claim
34 words
The combination recited in claim 15 wherein means is provided to control the speed of the metering device at a fixed ratio to the speed of scanning and wherein the said ratio is adjustable.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-12 | 1974-10-12 | 1975-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-12 | 1978-10-12 | 1979-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-12 | 1982-10-12 | 1983-04-13 | $7700.00 | Window Closed / Lapsed |