Simple is better, and an Onyx GSF/D Valve is as simple as it gets: A rubber sleeve inside an iron shell. Inject air into the shell - the rubber sleeve collapses, and flow stops. Release the air, the sleeve pops open and flow resumes. Ideal for dry cement, plaster, flour, sugar, coffee beans, plastic pellets, and whatever dry material you’re trying to move from point-A to point-B.
