dymax 826 User Manual - Page 12

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Model 826 Dispensing Valve User Guide

Operating the Dispensing Valve

Figure 7. Stages of Valve Operation

Shut Off

Start Up

When the valve is off/unactuated, the pinching surface of the spring-closed Upper Piston

(Figure 7, A) prevents flow by collapsing the Tube (Figure 7, B). The Pinch Stop Adjusting Screw

(Figure 7, C) limits the amount of pinch, which limits the stress on the Tube, extends the tubing

life, and insures shot repeatability. The blunt Lower Piston (Figure 7, D) is held in its open

position by a spring. The Adjusting Screw (Figure 7, E), which determines the amount that this

piston will close the tubing when actuated, is set to a position that will allow approximately

50% tube closure.

Dispense

When the valve is on, the air moves the Upper Piston (Figure 7, A) back to the Adjustable Stop

(Figure 7, F). This stop controls the amount the tube opens, which in turn controls the rate of

flow through the tube. These actions, combined with nozzle size (if a nozzle is used), fluid

pressure, and the amount of time the 826 valve is open, governs the amount of fluid