Dangerous statement.  How many bins have you seen with sledge-hammer marks around the discharge cone?  It's easy to under estimate how important feeder selection is for consistent material flow.  You must select a feeder that not only controls the flow but works well with the flow properties of your bin.

People go to great lengths to develop the proper bin design based on the flow properties of their material, after the fact!  "The Fix" usually entails wither retrofitting an existing funnel-flow bin or designing a new bin to ensure a mass-flow pattern.  This fix can be an expensive liner or steeper hopper angles and as such, you can destroy this effort simply by selecting an improperly-designed feeder.

Bin and feeder design go hand-in-hand.  The feeder must work in unison with your bin and:

• Suit your materials flow properties
• Work with the bin outlet shape
• Withdraw material uniformly across the outlet's entire cross-sectional area
• Minimize the vertical loads applied to the feeder
• Accurately control the discharge rate

There are many types of feeders available to suit every application.  You must decide which type is appropriate for a particular application.   Here are several items to consider:

• Volumetric vs. gravimetric feeding.  Do you need to actually weigh the amount of material discharged or can it discharge by it's volume.
• Feeder Selection.  Screw-, belt-, rotary valve-, vibratory- and louvered-type feeders are all available and have their own advantages and disadvantages.
• Environmental conditions.  Does your feed system need to be enclosed or dust-tight because of the material is dusty or toxic?
• Feeder effects on material.  Is your material brittle and subject to particle attrition?

There are many other considerations when selecting a feeder, too numerous to mention here.  In future articles I will address more specific feeder applications.

So put your sledge-hammer away!  Remember that the feeder design is as important as bin design.  If your having troubles, ask a experienced solids flow expert to provide guidance and expertise for your particular bin and feeder application.

Help others by posting your comments, suggestions and experiences with bulk solids feeding or any other materials handling concerns you may have on our On-Line Help Forum.  For past Ask Joe ! Articles, visit the Ask Joe! Archived Articles.

Guest articles for the Ask Joe! Column are always welcome, for more information please contact Joe Marinelli directly at his email address:  joe@solidshandlingtech.com.