Patent ID: 6904925

Claim:
A gas assist mold dump valve comprising: a gas controller operable to provide a first fluid stream at a first pressure; said first pressure being regulated by said gas controller; a mold cavity operable to receive a fluid from the first fluid stream and discharge the fluid in a second fluid stream at a second pressure; a regulator having an inlet, an outlet and a vent, the inlet being in fluid communication with the gas controller, the outlet being in fluid communication with the mold cavity, the vent having a vent seat and being in fluid communication with the mold cavity; and a piston having a dome end and a seat end, the piston being mounted in the regulator for reciprocal movement toward and away from the vent seat and being dimensioned such that the regulator is calibrated to have a near 1:1 dome-to-seat area ratio, the seat end being engagable with the vent seat to open and close the vent, the dome end being in fluid communication with the inlet, the second fluid stream acting on the seat end of the piston and the first fluid stream acting on the dome end of the piston such that the seat end contacts the vent seat and movement of the piston is in positional balance and wherein an increase in the second pressure relative to the first pressure moves the seat end out of contact with the vent seat such that excess pressure in the second fluid stream relative to the first fluid stream is discharged from the mold cavity.