How Much Control Is Achieved with Volumetric vs. Gravimetric Material Feeding?

Whether you work in the manufacturing or production industry, you need the right feeder system to regulate the flow of bulk materials into your company’s machinery. Feeder systems are typically used in conjunction with other types of material handling equipment, including conveyors, lump breakers, and mixers, to name a few.

There are two basic variations of feeder operations known as volumetric and gravimetric. Understanding the differences will help processors select and implement the best type of equipment for their application needs.

Volumetric Feeding

The principle of feeding volumetrically starts with keeping the auger full. We know the volume that is displaced by the auger in the nozzle, the pitch of the auger, and the rotational speed. So an auger with a one-inch pitch that is turning at 100 revolutions per minute will move the volume of material forward 100 inches per minute. Varying the rotational speed of the auger provides linear control of the volume of material being dosed.

This method provides precise, consistent, accurate, and repeatable metering with linear control with materials that are considered “good” powders. A good powder has a consistent bulk density and manageable characteristics.

Volumetric feeding falls short of capacity requirements when a material has a varying bulk material density. Material that can vary widely in bulk density within a batch will struggle to meet dosing requirements with a Volumetric feeder.

Gravimetric Feeding

Gravimetric feeders (loss in Weight or gain in weight) provide a means for dosing discreetly by weight or metering continuously. It offers methods for recording and tracking materials used and can provide the means to run recipes for dosing systems.

A typical LIW system can cost double the initial purchase price of a volumetric feeder because it adds a scale, control module, and a microprocessor-based HMI. However, overall control, record keeping, and accuracy gained with the Gravimetric feeder are necessary for some applications regardless of the overall cost.

Choosing the right gravimetric feeder or volumetric feeder for your application is important to the cost and quality of the output of your facility. The basics are outlined here, but speaking with a bulk material handling expert to design the optimum system for your application is important to achieving quantifiable savings in the long-run.

Benefits of a Feeder from Hapman

Feeder systems from Hapman are designed for a wide range of materials. A few of the benefits to purchasing Gravimetric feeders or Volumetric Feeders from Hapman include:

  • Measuring with precision
  • Achieving superior volumetric performance
  • Cleaning easily
  • Design versatility
  • Maintaining material quality
  • Ideal for silos and surge hoppers
  • Getting the strength and stability of structural tube-frame construction with the ability to support large hoppers on ancillary equipment

If you need a feeder for your applications, don’t hesitate to contact the experts at Hapman for more information. Hapman’s line of Volumetric and Gravimetric Industrial Feeders provide you with the accuracy and efficiency that you need in your dosing application. Whether it be the Flexible Wall feeder or the U-trough Screw Feeder, Hapman’s wide variety of industrial feeders will provide you precisely what you need, when you need it.