Fluid handling – Liquid level responsive or maintaining systems – By float controlled valve
Reexamination Certificate
2000-12-21
2001-11-20
Walton, George L. (Department: 3753)
Fluid handling
Liquid level responsive or maintaining systems
By float controlled valve
C137S409000, C137S448000, C405S096000
Reexamination Certificate
active
06318404
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a backflow valve and, in particular, a backflow valve with a side mounted closure gate.
BACKGROUND OF THE INVENTION
A backflow valve, also known as a backwater valve, is used to prevent a reversal of flow in a flow line. An example of a backflow valve is disclosed in Canadian Patent 2,114,602 and corresponding U.S. Pat. No. 5,406,972 granted to Coscarella et al.
The Coscarella et al reference discloses a backflow valve that has a pivoting closure gate with an open position to accommodate flow in a desired flow direction and a closed position to close off the flow line when there is a reversal of flow. The closure gate is hinged to the bottom of the valve housing. In the open position, flow passes over the closure gate with the closure gate serving as a spillway. Secured to the closure gate is a float. When the level of liquid rises, the float causes the closure gate to rise and the reversed direction of flow pushes the closure gate into the closed position.
The disadvantage of the backflow valve disclosed in the Coscarella et al reference is that when in the open position the liquid flow is always passing over the closure gate. In some applications, it would be advantageous to have a side mounted closure gate with the closure gate positioned to one side of the flow stream in order to reduce the exposure of the closure gate to the liquid flow. The closure gate disclosed in Coscarella et al, however, would not operate if the valve body of Coscarella et al were positioned on its side.
SUMMARY OF THE INVENTION
What is required is an alternative configuration of backflow valve in which there is a side mounted closure gate.
According to the present invention there is provided a backflow valve which includes a valve body adapted for use in a substantially horizontal orientation. The valve body has a top, a bottom, and opposed sides. A flow passage extends through the valve body. The flow passage has a longitudinal axis. A closure gate is pivotally mounted along an offset substantially vertical pivot axis to one of the opposed sides of the valve body for movement between an open position in which the closure gate is positioned on a plane substantially parallel to the longitudinal axis of the flow passage and a closed position in which the closure gate is positioned transverse to the longitudinal axis. A closure gate engaging profile is positioned in the bottom of the valve body along the one of the opposed sides to which the closure gate is pivotally mounted. The closure gate is locked in the open position by the closure gate engaging profile. The closure gate is capable of limited axial movement along the vertical pivot axis. The closure gate has a float which causes the closure gate to float free of the closure gate engaging profile in the bottom of the valve body as water rises. Means are provided for biasing the closure gate into the closed position. The closure gate moves to the closed position upon floating free of the closure gate engaging profile in the bottom of the valve body.
With the backflow valve, as described above, the closure gate is held in the open position to one side of the flow passage by the closure gate engaging profile. When liquid starts to rise, the closure gate moves to the closed position upon floating free of the closure gate engaging profile in tile bottom of the valve body.
Although beneficial results may he obtained through the use of the backflow valve, as described above, for improved performance it is preferred that the side closure gate be further removed from the liquid flow. Even more beneficial results may, therefore, be obtained when the valve body has a closure gate accommodating cavity in one of the opposed sides and the closure gate is positioned in the closure gate accommodating cavity when in the open position.
Although beneficial results may be obtained through the use of the backflow valve, as described above, debris floating behind the closure gate could potentially adversely affect the opening and closing of the closure gate. Even more beneficial results may, therefore, be obtained when the valve body has a baffle which restricts flow behind the closure gate when the closure gate is locked in the open position.
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Product information for the ZURN Z-1091 Backwater Valve, Zurn Industries Limited, 1 page, dated at least as early as Dec. 2000.
Davis & Bujold P.L.L.C.
Walton George L.
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