Iris valves: How they work and how to apply them
The compact, inexpensive iris valve can gently control the gravity-flow discharge of many free-flowing materials in dry bulk solids handling applications. This article explains how the iris valve operates, how it can and can't be applied, what construction materials are available for valve components, and the valve's pros and cons.
Most of us are familiar with the common iris mechanism, a simple device that opens and closes a circular hole. Common examples are camera shutters and the irises in our eyes, which both control the entrance of light. Maybe you've even seen iris doors opening and closing in space ships in sci-fi films. The iris mechanism also has a place in the real world of dry bulk solids handling, where it's called an iris valve. The iris valve's function is to gently control the discharge of free-flowing powders, granules, and pellets -- including chemicals, food and dairy products, pharmaceuticals, minerals, and plastics -- in gravity-flow applications.