Patent ID: 7591450

Claim:
A valve body and seal assembly having a longitudinal axis, said valve body and seal assembly comprising: a valve body substantially symmetrical about said longitudinal axis, said valve body having at least one circumferential seal retention groove and a frusto-conical valve body impact area for contacting a valve seat; and an elastomeric seal cast-in-place in at least one said circumferential seal retention groove, each said elastomeric seal being substantially symmetrical about said longitudinal axis and comprising: a first seal section having a frusto-conical external surface portion for contacting a valve seat, said first seal section comprising a first polyurethane; and a second seal section, at least a portion of said second seal section lying between one said circumferential seal retention groove and at least a portion of said first seal section, said second seal section contacting said first seal section along a substantially non-planar intra-seal interface, and said second seal section comprising a second polyurethane having a lower modulus than said first polyurethane; wherein said substantially non-planar intra-seal interface comprises at least one frusto-conical portion substantially geometrically similar to said frusto-conical valve body impact area and substantially geometrically similar to said first seal section frusto-conical external surface portion.