Patent ID: 7118352
Filing Date: 2006-10-10
Classification: G05D,Y10T

Abstract:
1. A metering device for a liquid medium under pressure, the metering device comprising: a housing having an inlet and an outlet for said liquid medium, said housing including a first chamber having an open end communicating with said outlet; a first check valve means in said housing, said first check valve normally biased to close said open end of said first chamber; a first piston having a drive end, said first piston slidably received and operatively disposed in said first chamber, said first piston and said first chamber defining a metering chamber; means to conduct said liquid medium from said housing inlet to said metering chamber; a second check valve located in said housing, received and operatively disposed in said first piston drive end and moveable between and including at least a first position and a second position, whereby pressure from said liquid medium moves said second check valve; and said first piston forcing said liquid past said first check valve means to completely evacuate said metering chamber on each working stroke to thereby generally preclude entrapment of air in said metering chamber.