Fluid handling – Systems – Flow path with serial valves and/or closures
Reexamination Certificate
2000-01-11
2001-11-06
Lee, Kevin (Department: 3753)
Fluid handling
Systems
Flow path with serial valves and/or closures
C251S264000, C277S308000, C184S006180
Reexamination Certificate
active
06311726
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to stuffing box packing systems used in industrial pumps, most notably, process or centrifugal pumps. More particularly, the invention controls the rate of water flow, as a function of pressure, to process pump stuffing boxes, in order to optimize the functioning and increase the longevity of the packing around the pump shaft.
2. Description of Related Art
To maintain in good working order the packing or braided, rope-type, packing squares, in the stuffing box around the shaft of an industrial pump has been a persistent problem in the food service, milling, chemical, injection molding, mixing, refinery (grinding) and other industries that move large volumes of material. The packing around the shaft of the pump must be kept moist with water so that the stuffing box serves its intended function to properly cool, lubricate and seal the pump shaft, and protect surrounding parts.
One of the biggest problems in the past has been caused by over-flushing of the packing material, which results in outward migration of elasticizers from the fibers of the packing material. As a result, the packing becomes brittle, loses its own lubricant and ultimately, the packing itself can tear away at the shaft, and must be replaced.
Another problem caused by the over-flushing of water into the packing is that when water leaks out from the packing, it can travel to the gear box, cause bearing failure, with the result that the pumps must then be rebuilt.
Finally, over-flushing of the stuffing box raises economic and ecological considerations, both of which remain a concern with respect to those methods used today for providing water flow to industrial pumps.
Patents directed towards the control of the flow and pressure of water or other fluids, among others, include: U.S. Pat. No. 787,327 issued to G. H. Dworzek, U.S. Pat. No. 1,837,001 issued to J. C. White, U.S. Pat. No. 5,282,493 issued to Schwartz et. al, U.S. Pat. No. 5,771,921, issued to Johnson, U.S. Pat. No. 5,831,158 issued to Schloetterer et. al. and Great Britain Pat. No. 1,565,649.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the invention to increase the useful life of the shaft of a process pump or centrifugal pump or, any pump that maintains a stuffing box with standard packing material, e.g. braided, rope-type, etc. The application may also include stuffing boxes associated with hydropower.
It is another object of the invention to maintain the packing with a steady drip-flow of water to keep the packing moist and elastic, but not so moist that the elasticizers migrate out of the packing, causing it to become brittle. Optimal moisture content of the packing lubricates the pump shaft, keeps the shaft at the proper temperature, and maintains the packing for a proper shaft seal, so as to prevent moisture from entering the gear box or other locations that would cause permanent damage to the pump machinery. Furthermore, limiting the flow of water to the stuffing box of an industrial pump, to a rate no greater than that which is required to insure its proper functioning, has both economic and ecological benefits rooted in conservation.
It is a further object of the invention to employ a pressure-sensitive adjustment screw, having a “soft-touch adjustment” gasket at the screw end, so as to optimize the flow rate of the packing water as a function of the pressure differential between the inlet pressure and the stuffing box pressure. A tough rubber gasket on the adjustment screw end also prevents damage to the bore, such as that which may be found in connection with the use of a needle valve, or a mechanical seal.
Still another object of the invention is to provide proper seals throughout the adjustment screw housing assembly.
Finally, it is an object of the invention to maintain additional safety features such as a check valve to stop the back flow when the inlet pressure decreases or shuts off; and two corresponding ball valves which enable an operator to change the pressure gauges while the machinery is still running.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
REFERENCES:
patent: 787327 (1905-04-01), Dworzek
patent: 1837001 (1931-12-01), White
patent: 2067335 (1937-01-01), Pardee
patent: 3530891 (1970-09-01), Welland
patent: 5282493 (1994-02-01), Schwartz et al.
patent: 5598902 (1997-02-01), Lin
patent: 5771921 (1998-06-01), Johnson
patent: 5831158 (1998-11-01), Schloetterer et al.
patent: 5992444 (1999-11-01), Junttila
patent: 453531 (1927-12-01), None
patent: 1 565 649 (1980-04-01), None
Lee Kevin
Litman Richard C.
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