Loss-In-Weight Feeders

Volumetric feeders rely on the bulk density of the product being constant. A Loss-In-Weight feeder can be defined as a self learning volumetric feeder where the controller compensates for bulk density changes on a continuous basis.

The Loss-In-Weight system is based on a suitably selected weigh hopper with load cells and a feeder, be it belt, screw or a vibratory feeder. The weight loss of the weigh hopper is recorded over time by the Loss-In-Weight controller which will then make adjustments to the feeder to delivery the correct rate of flow rate.

Loss-In-Weight feeders are typically used on extruders or systems where additives are dosed on a continuous basis at low flow rates. A combination of belt weigh feeders and Loss-In-Weight feeders may be appropriate in certain instances, depending on the process design and material flow properties.

Loss-In-Weight feeders can also be used for liquids where product will be pumped into a continuous process.

A Loss-In-Weight feeder will typically go through the following sequence:

• 1. Rapid refill of the Loss-In-Weight weigh hopper. During this part of the sequence the controller will be in the volumetric mode.
• 2. Delay to stabilize the reading.
• 3. Gravimetric discharge mode until the weigh hopper low level is reached.

Every Loss-In-Weight feeder is designed to suit specific client requirements.