Dual non-contacting mechanical face seal having concentric seal faces

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face extending between an outer surface of said first seal ring and an inner surface of said first seal ring,
• a second seal ring having a second seal face, said first and second seal faces being opposed to one another,
• one of said first seal ring and said second seal ring being adapted to rotate with said rotatable shaft, the other of said first seal ring and said second seal ring being restrained from rotating, and
• a plurality of grooves formed in said first seal face for receiving a fluid introduced to said first and said second seal faces, said plurality of grooves being positioned between said outer surface and said inner surface of said first seal ring to form two concentric seal faces on said first seal face, and said second seal face being dimensioned to seat over said grooves and at least a portion of said two concentric seal faces when assembled.

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face, said first seal face having a first portion and a second portion,
• a second seal ring having a second seal face, said second seal face being opposed to said first seal face,
• one of said first seal ring and said second seal ring being connected to said rotatable shaft to rotate therewith, the other of said first seal ring and said second seal ring being connected to said housing,
• a plurality of pumping grooves formed in said first portion of said first seal face for receiving a fluid introduced between said first portion and said second seal face and for producing a hydrodynamic fluid force and a hydrostatic fluid force between said first portion and said second seal face to cause separation of at least a portion of said first portion from at least a portion of said second seal face, and
• a fluid conduit formed through said second seal ring, said fluid conduit having an opening at said second seal face for communicating with said plurality of grooves to provide fluid to said grooves.

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face including a first portion and a second portion, said portions being configured to form dual, concentric sealing surfaces on said first seal face,
• a second seal ring having a second seal face, said second seal face being opposed to said first seal face,
• one of said first seal ring and said second seal ring being adapted to rotate with said rotatable shaft, the other of said first seal ring and said second seal ring being restrained from rotating,
• means for introducing a fluid between said first portion of said first seal face and said second seal face, and
• means for introducing a closing fluid to a rear surface of said second seal ring to provide a closing force on said second seal ring, said closing force acting upon a portion said second seal face overlapping said first portion of said first seal face.

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face including a first portion and a second portion, said portions being configured to form dual, concentric sealing surfaces on said first seal face,
• a second seal ring having a second seal face, said second seal face being opposed to said first seal face,
• one of said first seal ring and said second seal ring being adapted to rotate with said rotatable shaft, the other of said first seal ring and said second seal ring being restrained from rotating,
• means for introducing a fluid between said first and second seal faces to establish a gap having a selectable thickness between said seal faces, and
• a fluid control system for adjusting the gap thickness during operation of the seal by controlling pressure of the fluid introduced between said first and said second seal faces.

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face, said first seal face having an outer portion and an inner portion,
• a second seal ring having a second seal face, said seal faces of said first and second seal rings being opposed to each other when assembled,
• one of said first seal ring and said second seal ring being adapted to rotate with said rotatable shaft, the other of said first seal ring and said second seal ring being restrained from rotating,
• means for producing a primarily hydrostatic fluid force between at least a portion of said outer portion of said first seal face and at least a portion of said second seal face, and
• means for producing a hydrodynamic fluid force and a hydrostatic fluid force between at least a portion of said inner portion of said first seal face and at least a portion of said second seal face.

A mechanical face seal for providing fluid sealing between a housing and a rotatable shaft, said seal comprising

• a first seal ring having a first seal face, said first seal face having a first portion and a second portion, and
• a second seal ring having a second seal face, said seal faces of said first and second seal rings being opposed to each other when assembled,
• one of said first seal ring and said second seal ring being adapted to rotate with said rotatable shaft, the other of said first seal ring and said second seal ring being restrained from rotating,
• wherein said seal faces are configured to produce a primarily hydrostatic fluid force between at least a portion of said first portion of said first seal face and at least a portion of said second seal face, and
• wherein said seal faces are configured to produce a hydrodynamic fluid force and a hydrostatic fluid force between at least a portion of said second portion of said first seal face and at least a portion of said second seal face.

A method of providing fluid sealing between a housing and a rotatable shaft, the method comprising the steps of

• providing a seal including
• a first seal ring having a first seal face, the first seal face having a first portion and a second portion, and
• a second seal ring having a second seal face, the seal faces of the first and second seal rings being opposed to each other in a sealing relationship when assembled, and
• inhibiting contact between the seal faces by
• producing a primarily hydrostatic fluid force between at least a portion of the first portion of the first seal face and at least a portion of the second seal face to cause separation of at least a portion of the first portion from at least a portion of the second seal face, and
• producing a hydrostatic fluid force and a hydrodynamic fluid force between at least a portion of the second portion of the first seal face and at least a portion of the second seal face to cause separation of at least a portion of the second portion from at least a portion of the second seal face.