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To dispense, first fill the tube with fluid (priming). Figure 1 shows the dispense tube is filled after having been connected to a pressurized reservoir containing the material being dispensed.
The valve controller is placed in its Prime Mode and the valve is actuated using the trigger switch on the controller's front panel or a remote switch connected to the controller's trigger port.
This action causes all 4 pistons to release their hold on the tube and allows the fluid in the reservoir to flow through the tube and out the nozzle for the amount of time the trigger is held in its on position. The flow removes all the air that was in the tube. When a solid stream of fluid emerges from the nozzle the operator releases the trigger switch. The release automatically actuates the pistons in the following manner (see Fig. 2).
First piston V3, the outlet valve, closes, this stops the flow through the tube. Then the beveled end of piston V1, inlet valve, closes. The V2 piston, which is blunt, remains open against its adjustable micrometer stop, and the blunt V4 piston, the suck-back piston, also remains open against its adjustable stop. The mode switch on the controller is then placed in its Automatic Dispense position. When the controller is triggered the following actions occur (see Fig. 3).
The outlet valve V3 opens, simultaneously the blunt piston at the V4 position partially closes against it preset stop. Then the positive displacement piston V2 moves forward until it stops against its preset, but adjustable, stop.  This action displaces the amount of material determined by the dispense tubes inside diameter, the amount the blunt displacement piston travels from its adjustable rest position, and the diameter of blunt piston. When the displacement piston completes its stroke the outlet piston V3 closes the tube. As soon as this action is complete, the suck back piston at position V4 moves back to its open position, this causes the tube to return to its original shape. This action creates a partial vacuum in the tube and nozzle which sucks back a specific, adjustable amount of material. The following displacement piston V2 then moves back to its open position. Following this action the V1 piston closes the inlet. The valve is now set for its next shot.
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