Loading, unloading, conveying or transferring bulk materials, such as powder, food or chemicals, often requires a temporary stoppage of flow or a containment of residual material. Choosing the right valve for the application depends on the requirements of the system, process, material characteristics, and potential for no-flow or static columns of material. These valve selection elements, combined with the cost of the valve selected, will help determine the one best suited for each unique application.
There are many different kinds of valves for bulk material handling, and it may be tough to tell the difference between the different types. However, it’s important to learn about which valves are ideal for your bags.
A commonly used valve in bulk material handling is an iris valve. Typically, the valve’s function is to “gently control the discharge of free-flowing powders, granules, and pellets, including chemicals, food and dairy, pharmaceuticals, minerals, and plastics in gravity flow applications” (How Does an Iris Valve Work, Vortex, 2016).
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Using this description and applying it to various aspects of a bulk material handling system identifies whether an Iris valve will work well on the bulk bag discharge of a Bulk Bag Unloader. The design of the Iris valve allows an operator to untie a heavy-duty bulk bag and meter the material discharge. It also allows for the bulk bag to be closed off and retied during material flow or when the bulk bag is empty. In each of these cases, the loss of materials and dusting are kept to a minimum.
Because the ultimate goal of your bulk bags is to control and limit the discharge of powder and other materials, you’ll need a valve that can securely control the materials while the bulk bags are closed. The iris valve is one of the most secure ways to ensure that the product within your bulk bags stays inside without allowing any discharge or dust to occur.
There are three common handle options for closure of the valve (see the image below).
Unlike a conventional butterfly valve or slide gate, where a disc or blade crosses and obstructs the column of flowing material, the iris valve has a circular opening that closes toward the center of the material column. When the valve opens, its circular opening creates a small “cone” of material that flows into the receiving container’s center. This provides easier filling into the container.
The other valve option specifically for a Bulk Bag Unloader application is a pinch valve, shown below. This valve has pneumatically operated plates, which are designed to close in a static material column. These valves are more expensive than an iris valve; however, they offer the ability to close off a material section in the event a hopper is full or there is a material back up within the system for any reason.
To learn more about the flexibility and ease of use of the iris valve, click here to read an article by Vortex Valves.
The professional team at Hapman is available to help with all of your material handling needs. Contact Hapman today for more information about the iris valve and how it can help with bulk material handling, as well as with any questions you might have about bulk bag unloading and bulk bag dump stations.