Dual Pinch Valve
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
A dual pinch valve to provide drip-free dispensing of photoresist and other fluids. In the operation of the valve, pressurized fluid passing through tubing 1 in Fig. 1 is pinched at three points. A shut off anvil 2 pinches tube 1 to cut off flow and to provide the metering point. The second pinch point is the flow equalizer 3. A suck back anvil 4 provides the third pinch. An internal spring 5 is included with each piston/piston plate assembly 6, with a diaphragm completing the assembly. By external sequencing and timing, the valve will operate as described below. In the "off" position anvil 2 pinches the tube closed and anvil 4 is open. Activating the valve opens the anvil 2 for a predetermined time, thereby dispensing fluid. Then, both anvils 2 and 4 close simultaneously. After a predetermined time, usually 0.