How to Choose the Best Loss in Weight Feeder

How to Choose the Best Loss in Weight Feeder - Define Your Material and Process Requirements
Selection dimension	What to define	Example requirement or material data	Feeder selection implication
Material identity and condition	Specify the material, grade, moisture condition, temperature, and whether its properties vary between batches.	Example: dry polymer pellets; note any recycled-content variation or temperature changes.	Test the actual production material. Changes in moisture, temperature, or formulation can affect flow and feeding behavior.
Bulk density	Provide loose and, where relevant, aerated or settled bulk density in kg/m³ or lb/ft³.	Example: a powder measured at 500 kg/m³; confirm the value using the material and test method used at the plant.	Density affects hopper capacity, screw fill, and the relationship between feeder speed and mass flow.
Particle size and shape	Record the particle-size distribution, largest particles, fines content, and particle shape.	Example: pellets around 3–5 mm with a small fines fraction; actual distribution should be measured.	Particle size helps determine screw geometry and clearance; irregular or broad-size materials may segregate or feed unevenly.
Flowability and cohesion	Describe whether the material is free-flowing, cohesive, prone to bridging, or sensitive to aeration. Use shear testing when flow behavior is uncertain.	Example: a fine powder that forms a stable arch after standing.	Cohesive materials may need a suitable agitator, mass-flow hopper design, or other flow aid. Confirm the solution through testing.
Required feed-rate range	State the minimum, normal, and maximum continuous rates, with units and expected operating duration.	Example: 10–100 kg/h continuous, with regular operation near the middle of the range.	Select a feeder whose usable range covers the operating points; verify performance at both low and high rates.
Accuracy and repeatability	Define the allowable deviation, averaging period, and test conditions. Distinguish short-term variation from long-term accuracy.	Example: a process target of ±1% over a specified test interval, subject to validation with the actual material and rate.	Accuracy depends on the feeder, load-cell system, control settings, installation, and material behavior. Request a documented performance test.
Batch size and hopper autonomy	Define how long the feeder should run between refills and the available space for the hopper and refill equipment.	Example: at 50 kg/h, a 25 kg usable inventory provides about 30 minutes of operation before accounting for refill and reserve requirements.	Size the usable inventory for the required autonomy. Allow for headspace, refill strategy, and stable weighing during operation.
Refill method and refill disturbance	Specify manual filling, vacuum conveying, or another refill method, including refill frequency and whether feeding must continue during refill.	Example: automatic refill every 20 minutes while maintaining a steady downstream feed.	Refill can introduce weight disturbances. Define how the system will manage refill and verify performance during the refill cycle.
Process interface and control	Document downstream equipment, control signals, operating modes, alarms, and required data communication.	Example: continuous setpoint from a plant controller, with feed-rate feedback and low-material alarm.	Confirm signal types and control responsibilities with the process team before specifying the feeder and controls.
Material and site conditions	Identify dust, abrasiveness, corrosiveness, temperature, washdown, hazardous-area classification, and applicable hygiene requirements.	Example: an abrasive powder in a dry indoor area, with dust containment required at transfer points.	These conditions affect contact materials, seals, enclosure, cleaning access, and required safety or compliance features.
Validation and acceptance criteria	Agree on the test material, target rates, run duration, refill conditions, sampling method, and acceptance limits before purchase.	Example: test at minimum, normal, and maximum rates using representative production material and record the measured deviation.	A defined acceptance test makes feeder performance comparable and helps confirm suitability for the real process.