| 摘要 |
Pneumatic valve construction comprising a valve chamber having opposing inlet ports with opposing axially located valve seats, and a ball therebetween constructed and arranged to move off of one valve seat into engagement with the other valve seat upon an unbalance in pressure. The construction includes a bottom outlet port that extends to the top of another larger cylindrical chamber having an elastomeric piston therein with fluid flow clearance between the piston and the side walls of the chamber. A tubular exhaust port extends axially inwardly from the bottom side of the chamber to abut the bottom side of the rubber piston. An annular fluid flow chamber exists between the tubular exhaust seat and the side walls of the cylindrical chamber to allow flow past the piston through the space to a delivery port. The rubber piston includes a conically shaped lip which extends out into engagement with the side walls of the cylindrical chamber to help center the piston in the cylinder and to prevent reverse flow from the outlet port back to the inlet ports.
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