Fluid handling – Line condition change responsive valves – Direct response valves
Reexamination Certificate
2001-09-04
2003-07-01
Buiz, Michael Powell (Department: 3753)
Fluid handling
Line condition change responsive valves
Direct response valves
C137S514000, C251S054000, C251S065000
Reexamination Certificate
active
06585000
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to pressure relief valves for releasing pressure from a closed system and more particularly, to a pressure relief valve typically including a valve housing provided on a pressure relief conduit which receives the pressure from the system. A valve opening establishes communication between the valve housing and the pressure relief conduit, and a substantially arcuate valve body is pivotally mounted in the valve housing for sealingly and slidably engaging the valve opening. Accordingly, the valve body is capable of pivoting between a first position to close the pressure relief conduit and a second position to open the pressure relief conduit as the valve body slidably traverses the valve opening. A bias mechanism biases the valve body in the closed position in such a manner that the valve body pivots from the closed position to the open position against the bias mechanism and opens the pressure relief conduit, responsive to a threshold pressure impinging against the valve body in the pressure relief conduit.
A pressure relief device, which can be either a pressure relief valve or a rupture disk, is a mechanical device used to prevent a system such as a process unit, piping network, vessel or tank from over-pressurizing. When the system pressurizes to the maximum allowable working pressure or set pressure, the pressure relief device opens responsive to the pressure and relieves the system pressure down to a certain point, after which the pressure relief device closes to prevent further loss of pressure from the system
A variety of pressure relief valves have been developed for relieving buildup of pressure from a system Patents of interest in this regard include U.S. Pat. Nos. 3,482,603; 3,817,278; 4,253,489; 4,669,500; 5,145,005; 5,159,981; 5,236,009; 5,310,005; 5,794,655; and 6,152,173.
Many of the conventional, or balanced, pressure relief valves known in the art suffer from numerous disadvantages, including the requirement of a large pressure differential on opposite sides of the valve in order for the valve to stay opened and expel excess pressure. Most of the valves are designed to open at a fixed set pressure and cannot be adjusted to accommodate pressures of various magnitudes in other systems. The valves typically undergo excessive wear, particularly during high-performance operation. Moreover, the valve piston and valve seal are typically disposed directly in the flow path of the pressurized fluid, and this design subjects the piston and seal to continuous impact and accelerated wear when the valve is open. Many of the valves require complicated sizing calculations for installation. Finally, conventional balanced valves tend to close or reseat at about ten percent below the set pressure.
An object of the present invention is to provide a pressure relief valve which is capable of operating with a low pressure drop.
Another object of this invention is to provide a pressure relief valve which is characterized by high performance with low wear characteristics.
Still another object of the invention is to provide a pressure relief valve which can be easily installed and re-used in a variety of systems.
Yet another object of this invention is to provide a pressure relief valve which is capable of a variety of applications.
A still further object of this invention is to provide a pressure relief valve which can be set to open and close at predetermined pressures.
SUMMARY OF THE INVENTION
These and other objects of the invention are provided in a pressure relief valve for releasing pressure from a closed system when the pressure reaches a pretedermined magnitude in the system. The pressure relief valve typically includes a valve housing provided on a pressure relief conduit which receives the pressure from the system A valve opening establishes communication between the valve housing and the pressure relief conduit, and a substantially arcuate valve body is pivotally mounted in the valve housing for sealingly and slidably engaging the valve opening. Accordingly, the valve body is capable of pivoting between a first position to close the pressure relief conduit and a second position to open the pressure relief conduit as the valve body slidably traverses the valve opening. A bias mechanism biases the valve body in the closed position in such a manner that the valve body pivots from the closed position to the open position against the bias mechanism and opens the pressure relief conduit, responsive to a threshold pressure impinging against the valve body in the pressure relief conduit.
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Buiz Michael Powell
Harrison R. Keith
Krishnamurthy Ramesh
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