This single air actuated valve design serves two distinctly different purposes.
As a proportioning valve:
The proportioning signal is simply set to load virgin and regrind alternately – for a given number of seconds. The amount of each material loaded is not exact but satisfactory if It can be added to a self-contained vacuum loader or to a central system vacuum receiver when it is desirable to layer natural resin and regrind. You just need to approximate the percentage of each material required in the mix.
As a purge valve:
It can be added to a vacuum takeoff box beneath a drying hopper and it can be configured to convey material then purge material lines with either ambient or dry air. Air purging of material lines is a good way to clear out any stray pellets after each shot of resin is conveyed. This minimizes the opportunity for material to build up in conveying lines and cause line plugging.
For either application, the operational signal can come from a central control if the control is programmed for proportioning/purge. Otherwise, a separate control can be purchased to accomplish the proportioning or purge.
The inlet/outlet diameters are sized to match material line diameter.
NOTE: There is also DSV (Discharge Selection Valve) which is basically a Purge valve with relief so it can circulate dry air from the vacuum pump for Closed Loop Dry Air Conveying applications.
Features to look for: