The valve member includes a valve body and a seal. The valve body defines a first frusto-conical surface and an outside annular cavity. The seal extends within the outside annular cavity and includes a first tapered and circumferentially-extending surface adapted to sealingly engage the tapered surface of the valve seat. In another aspect, the seal includes an annular bulbous protrusion from which the first tapered and circumferentially-extending surface angularly extends, the first tapered and circumferentially-extending surface extending between the annular bulbous protrusion and the first frusto-conical surface of the valve body. In another aspect, an offset distance is defined between the first frusto-conical surface of the valve body and at least a portion of the first tapered and circumferentially-extending surface of the seal, the offset distance extending in a direction that is perpendicular to at least the first frusto-conical surface of the valve body.