Coupling apparatus

The sealing assembly for sealing against fluid flow through a space defined between a coaxial first member and second member, said first member having support means for supporting and retaining said sealing assembly in said space, said sealing assembly comprising:

• a first sealing subassembly disposed in said space in engagement with said support means and comprising first sealing means, first preventing means and second sealing means, said first sealing means being engaged with said first member and being spaced radially from said second member, said second sealing means being engaged with said second member, and, said preventing means being intermediate said first sealing means and said second sealing means and spaced radially from said second member,
• a second sealing subassembly disposed in said space comprising third sealing means, second preventing means and fourth sealing means, said third sealing means being engaged with said first member and being spaced radially from said second member, said fourth sealing means being engaged with said second member, and, said second preventing means being intermediate said third sealing means and said fourth sealing means and spaced radially from said second member, and
• spacer means disposed in said space for limiting movement of said sealing subassemblies toward each other, said spacer means being intermediate said first preventing means and said second preventing means,
• wherein a fluid moving in a first flow direction deforms said first sealing means into sealing engagement with said first member at a first predetermined fluid pressure, said second sealing means extends at an acute angle to said first flow direction so that said fluid deforms said second sealing means into sealing engagement with said second member at a second predetermined fluid pressure, said first preventing means and the radial extent of said radial space associated therewith prevent said second sealing means from deforming into said radial space associated with said first sealing subassembly and said fourth sealing means extends at an obtuse angle to said first flow direction so that said fourth sealing means allows said fluid moving in said first flow direction to pass thereby;
• and,
• wherein a fluid moving in a second flow direction deforms said third sealing means into sealing engagement with said first member at a third predetermined fluid pressure, said fourth sealing means extends at an acute angle to said second flow direction so that said fluid deforms said fourth sealing means into sealing engagement with said second member at a fourth predetermined fluid pressure, said second preventing means and the radial extent of said radial space associated therewith prevent said fourth sealing means from deforming into said radial space associated with said second sealing subassembly and said second sealing means extends at an obtuse angle to said second flow direction so that said second sealing means allows said fluid moving in said second flow direction to pass thereby.