Gravimetric feeding (also known as loss in weight feeding) is often required in a continuous application. And when you are trying to gravimetrically feed a material that tends to flood, the results can be frustrating and discouraging because there is no control over the flow.
Such was the case in a recent project that HaF Equipment took on, needing to consistently gravimetrically feed cocoa.
Materials such as cocoa, starch, and protein powders tend to pose a challenge to a gravimetric feeder. Most feeders do not provide a way to control bulk density and get materials to mass flow out of even a small hopper - all of which is required for tough powders. And all of which is required for a successful project and a happy customer.
Before the cocoa even gets close to the discharge of the feeder, every detail needs to be looked at, and we start with the hopper. As product enters into a feeder hopper, we take every precaution to densify the powder. Free-flowing powders will easily flood feed and rush past the screw feeder like water leaving a sieve.
In the HaF design, a small surge with a live bin densifier works to increase a powders bulk density. This provides good powder control as it enters the feed chamber. The densified powder helps create a consistent flow, which also works in conjunction with the weigh scale for faster and more precise weighments.
When working with a powder that flood feeds, the feeder discharge detail is important. HaF uses a quick acting shut off valve, which provides a secure stop that prevents flooding past feeder at fresh fill. This shut off also provides a quick and secure way of shutting off flow from a trickle feed mode.
Even though the focus for this feeder was handling the challenging powder, HaF used it sanitary design eye to provide an easy-to-clean feeder to the customer.
The entire feeder is designed to be tool free, quick take apart for ease of cleaning, using proven HaF design methods developed over 25 years. Even the main densifier flex connection can be removed without the need for tools.
The cocoa gravimetric feeder is modular and comes in a range of sizes from 3 in. (pictured) to 6 in. Hoppers and densifiers are available in different sizes that allow for mix and matching of components for custom feeder sizing without the cost.
Every application is unique, so the most important aspect of any project is to connect with the end user. Communication is critical.
For more information, contact HaF Equipment (Maplewood, MN) at 651-653-5098 or www.hafequipment.com.