Sequence Of Operations

To dispense first we must first fill the tube with fluid (priming). This is accomplished in the following manner. First, the dispense tube is 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 caused 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 V 3, the outlet valve, closes, this stops the flow through the tube. Then the beveled end of piston V 1, inlet valve, closes.

The V 2 piston, which is blunt, remains open against its adjustable micrometer stop, and the blunt V 4 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 V 3 opens, simultaneously the blunt piston at the V 4 position partially closes against it preset stop.

Then the positive displacement piston V 2 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 V 3 closes the tube. As soon as this action is complete. The suck back piston at position V 4 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 V 2 then moves back to its open position. Following this action the V 1 piston closes the inlet.

The valve is now set for its next shot.