Patent ID: 6926867
Filing Date: 2005-08-09
Classification: B01L

Abstract:
1. A piston seal assembly for a pipette having a body, a piston, and a spring, the body including a shaft segment and a housing segment, the shaft segment defining a bore, the housing segment defining a cavity which is coaxial with the bore, the cavity having an inner surface and defining a shoulder, the piston including a rod segment disposed within the body, an operator segment disposed exterior to the body, and an engagement member disposed intermediate the rod and operator segments, the spring being disposed within the cavity and providing a biasing force between the shoulder of the body and the engagement member of the piston, the seal assembly comprising: an O-ring having radially inner and outer surfaces and axially separated first and second surfaces, the radially inner surface defining an opening, the first surface being adapted for engaging the shoulder; an integral, one-piece, substantially circular seal composed of UHMWPE having a radially extending rim portion and an axially extending sleeve portion, the sleeve portion extending axially through the opening of the O-ring and having radially inner and outer surfaces, the radially outer surface of the sleeve portion engaging the radially inner surface of the O-ring, the radially inner surface of the sleeve portion being adapted for slidably engaging the rod segment of the piston, the rim portion having axially separated first and second surfaces, the first surface of the rim portion engaging the second surface of the O-ring; and an integral, one-piece, substantially circular seat having a radially extending engagement portion and an axially extending indexing portion, the indexing portion having radially inner and outer surfaces, the engagement portion having axially separated first and second surfaces and defining an opening adapted for receiving the rod segment of the piston, the first surface of the engagement portion engaging the second surface of the rim portion, the second surface of the engagement portion being adapted for engaging an end of the spring, the radially inner surface of the indexing portion engaging the radially outer surface of the O-ring, the radially outer surface of the indexing portion being adapted for engaging the inner surface of the cavity.