Feeder Selection Guide
What You Need to Consider in Specifying the Right Feeder for Your Process
Coperion K-Tron has a full range of feeders for the process industries. Following is a brief overview of the many choices you have in selecting the best feeder for your process needs.
Use Volumetric Feeders for Materials with Consistent Bulk Density
Volumetric feeders control flow by discharging a consistent volume of material. They are best used when bulk density is consistent, long term feed accuracy is not critical, and feeder performance does not need to be documented. Coperion K-Tron offers two types of screw feeders: the economical single screw volumetric feeder and the twin screw volumetric feeder for difficult materials. For free flowing materials, the award winning Bulk Solids Pump (BSP) offers perfectly linear, highly accurate volumetric feeding that surpasses all other feeders, yet is economical to buy and operate.
Use Volumetric Feeders in Gain-in-Weight Batching
In gain-in-weight batching, volumetric feeders sequentially discharge into a weigh hopper, providing a weight-based formulation. For better accuracy and faster batch times, use loss-in-weight batch feeders
Use Gravimetric Feeders for Greater Control, Long Term Accuracy and Continuous Processes
Gravimetric feeders control material flow by weight and therefore require a scale. Gravimetric feeding provides greater feed accuracy than volumetric feeding. In addition to improving process quality, gravimetric feeders can document material content in the end product. Also know as weigh feeders, gravimetric feeders are an essential enabling technology when it comes to feeding bulk material in many continuous processes.
Two Types of Weigh Feeders
In gravimetric feeding you can choose between weigh belt feeders and loss-in-weight feeders. Each feeder type has a very different approach to weighing material flow and has its unique advantages. The best choice really depends on your application needs.
Use Weigh Belt Feeders for Higher Feed Rates and Where Headroom Is an Issue
Weigh belt feeders form a bed of material on the belt as material is extracted from a supply hopper. As material moves along the belt, it is continuously weighed, and belt speed is adjusted to maintain the desired flow rate off the end of the belt.
Weigh belt feeders work best with granular materials. They offer high feed rates, fit in where headroom is a problem, and do not require a refill device. In general, weigh belt feeders cost less to install, but they require more maintenance than loss-in-weight feeders and do not handle dust as well.
Use Loss-in-Weight Feeders for Difficult Materials or High Accuracy at Very Low Feed Rates
In loss-in-weight feeding, the entire feeder is continuously weighed, and the rate of weight loss from the system is controlled for the desired feed rate.
Since the feeder must be refilled periodically, either manually or by automatic means, proper feeder sizing and refill strategy can be important factors to successful implementation. Loss-in-weight feeders lend themselves to modular design and a variety of metering devices specifically appropriate to the material being fed.
Typical metering devices include single or twin screws, a vibrating pan, or (for liquids) a pump or valve. Loss-in-weight feeders are able to handle difficult materials and can achieve very low feed rates.
More Feeder Choices for Special Needs
You can find more feeder choices beyond this introductory page. Coperion K-Tron has engineered special feeding solutions for very low feed rates, very high feed rates, and for multi-feeder blending. To learn more, see Coperion K-Tron's feeding solutions for special applications.