Spool action valves are a balanced type “on/off” segmented valve. Applying pressure to the air inlet will force the spool forward, under tension from an internal return spring, dispensing the material. Releasing the air pressure results in the internal spring snapping back into position and closing the valve.
High pressure needle action valves require a VC1195N 4-way valve controller. Applying pressurised air from the controller retracts the needle with in the valve allowing the material to flow. Switching the air signal on the controller will return the needle to its seated position closing the valve.
Constant bead valves are designed to deliver a uniform bead dimension irrespective of any air pressure build-up at the opening of the valve and at the start of the bead. This neutralising pressure feature ensures a perfect bead with a clean cut-off of the material at the end of the bead path.