IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0314675
(1994-09-29)
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발명자
/ 주소 |
- Wasser James R.
- Volden Douglas J.
- Netzel James P.
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출원인 / 주소 |
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대리인 / 주소 |
Dorn, McEachran, Jambor & Keating
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인용정보 |
피인용 횟수 :
27 인용 특허 :
0 |
초록
▼
A double, back to back oriented mechanical end face seal arrangement for use in sealing pumps or other devices used in fluid transfer of toxic or corrosive fluid has an intermediate buffer fluid chamber into which a relatively inert gas, such as nitrogen, is provided for use as a buffer fluid, and i
A double, back to back oriented mechanical end face seal arrangement for use in sealing pumps or other devices used in fluid transfer of toxic or corrosive fluid has an intermediate buffer fluid chamber into which a relatively inert gas, such as nitrogen, is provided for use as a buffer fluid, and is maintained at a pressure which exceeds the process fluid pressure by at least 10 p.s.i. Each seal has a primary ring and a mating ring with gap maintaining means, such as spiral pumping grooves, formed in one of the rings which are shaped and dimensioned to pump the buffer gas through the first seal from the intermediate chamber into the process fluid chamber against the process fluid pressure and through the second seal from the intermediate chamber into the environment external to the housing and sealing area, thus avoiding the escape of the process fluid into the intermediate buffer chamber and thereby to the atmosphere. The inboard seal includes a first secondary sealing means disposed between one seal ring and the housing for sealing therebetween and a second secondary sealing means, disposed between the other seal ring and the shaft for sealing therebetween, the first and second secondary sealing means, which may comprise O-rings, each defining the boundary between the intermediate chamber and the process fluid chamber. The first and second secondary sealing means of the first rotary mechanical end face seal are sized and disposed to define radial walls in the back radial surfaces of each seal ring to thereby present essentially an equal area at an approximately identical radius, such that essentially the same mount of buffer fluid pressure acts on the back radial surfaces of each ring of the first rotary mechanical andface seal but in opposite directions and, on the process fluid side, the identical process fluid pressure acts on opposite sides of a portion of the respective rings of the first rotary mechanical end face seal essentially eliminating thrust forces acting on the first rotary mechanical end face seal.
대표청구항
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[ What is claimed is:] [1.] A method for sealing against leakage of process fluid under pressure within a housing along a rotatable shaft extending through a wall of the housing, said method comprising the steps of:utilizing a seal arrangement having:a first rotary mechanical end face seal including
[ What is claimed is:] [1.] A method for sealing against leakage of process fluid under pressure within a housing along a rotatable shaft extending through a wall of the housing, said method comprising the steps of:utilizing a seal arrangement having:a first rotary mechanical end face seal including a stationary seal ring for sealing connection to the housing and a rotary seal ring for sealing connection to the shaft, each said ring having radial surfaces, and each said ring including an annular generally radially extending sealing face, being coextensive with one of said radial surfaces spaced from at least one other of said radial surfaces thereof, and in relatively rotating, mating sealing relation with the sealing face of the other of said rings, one of said seal rings being axially movable relative to the other;a second rotary mechanical end face seal including a stationary seal ring for sealing connection to the housing and a rotary seal ring for sealing connection to the shaft, each said ring having an annular generally radially extending sealing face in relatively rotating, mating sealing relation with the face of the other of said rings, one of said seal rings of said second rotary mechanical end face seal being axially movable relative to the other said seal ring independently of the axial movement of the axially moveable ring of said first rotary mechanical end face seal;said first and second rotary mechanical end face seals including means directly biasing each of the axially moveable rings toward its associated stationary ring to maintain said annular sealing face of said axially moveable ring in said relatively rotating sealing relation to said annular sealing face of said stationary ring;said first and second rotary mechanical end face seals being axially spaced apart along the shaft and arranged to define, with said housing, an intermediate chamber therebetween;the relatively rotatable seal rings of said first rotary mechanical end face seal having a first annular circumference of said sealing faces exposed to the process fluid to be sealed within the housing, and a second annular circumference of said sealing faces exposed to said intermediate chamber;the relatively rotatable seal rings of said second rotary mechanical end face seal having a first annular circumference of said sealing faces exposed to said intermediate chamber, and a second annular circumference of said sealing faces exposed to the ambient environment external to said housing;said intermediate chamber including means for connection to a source of relatively inert gas barrier fluid at a gas barrier fluid pressure exceeding the pressure of said process fluid present at said annular seal face first circumference of said first rotary mechanical end face seal rings;said first rotary mechanical end face seal including gap-maintaining means to cause said seal to operate, during shaft rotation, as a gas lubricated, non-contacting seal in the presence of said gas barrier fluid at said gas barrier fluid pressure; andsaid first rotary mechanical end face seal further including means to cause said seal to operate, during shaft rotation, as a contacting seal in the absence of said gas barrier fluid pressure;supplying a relatively inert gas barrier fluid to said intermediate chamber at a gas barrier fluid pressure exceeding the pressure of said process fluid present at said annular seal face first circumference of said first rotary mechanical end face seal rings;operating said first rotary mechanical end face seal, during shaft rotation, in the presence of said gas barrier fluid pressure as a gas lubricated, non-contacting seal, and essentially eliminating thrust forces acting on said first rotary mechanical end face seal, by providing said first rotary mechanical end face seal with a first secondary sealing means disposed between one of said seal rings and the housing for providing a sealing connection therebetween and a second secondary sealing means disposed between the other seal ring and the shaft for providing a sealing connection therebetween, to define the boundary between said intermediate chamber and said process fluid within said housing, and sizing and disposing said first and second secondary sealing means of said first rotary mechanical end face seal to define radial walls in said other radial surfaces and thereby presenting essentially an equal area at an approximately identical radius, such that the essentially same amount of buffer fluid pressure acts on the radial surfaces of each of said rings of said first rotary mechanical end face seal but in opposite directions and on the process fluid side, the identical process fluid pressure thereby acting on opposite sides of a portion of each of said respective rings of said first rotary mechanical end face seal to essentially eliminate thrust forces acting on said first rotary mechanical end face seal.
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