Gravimetric Feeder (LIW & GIW)
Behpoo gravimetric feeders control mass flow rate in a closed loop to ±0.5 – 1% of rate. Capacities from grams per hour to 5,000 kg per hour, with turndown of 20:1 as standard.
A gravimetric feeder weighs what it actually delivers. The hopper, dosing element and drive sit on load cells; as material discharges, the falling weight is measured and the drive speed is corrected continuously to hold the set mass rate.
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This is what separates it from volumetric feeding. A volumetric feeder holds screw speed constant and hopes the bulk density has not moved. A gravimetric feeder measures the result and corrects it — so changes in moisture, particle size or compaction are absorbed automatically.
Behpoo builds two arrangements. Loss-in-Weight (LIW) feeders weigh the feeder itself and measure the rate of weight loss; this is the standard for continuous accurate feeding. Gain-in-Weight (GIW) systems weigh the receiving vessel instead, which suits batching into a mixer.
Refill is the one interruption in LIW operation: while the hopper is being recharged, weight is rising and the measurement is not valid, so the controller runs on the last known rate. Hopper sizing balances refill frequency against tare weight.
Benefits & Features
- Rate accuracy ±0.5 – 1% of rate
- Capacity range from grams/hour to 5,000 kg/hour
- Turndown 10:1 to 20:1 standard, up to 100:1 with twin screw
- Closed-loop correction absorbing bulk density variation
- LIW and GIW arrangements
- Refill management with automatic changeover
- Vibration-isolated weigh frame; ATEX execution available
Product Range
| Type | What it is | Typical use |
|---|---|---|
| Micro | Very fine twin screw, minimal tare relative to material | Grams/hour to about 10 kg/h — additives, pigments, catalysts |
| Small | Single or twin screw, the common minor-ingredient range | About 5 – 100 kg/h — masterbatch, additives |
| Medium | Single screw or vibratory tray — the standard industrial class | About 50 – 1,000 kg/h — dry mortar, feed, continuous mixing |
| Large | Large screw or weigh belt feeder | 500 to 5,000 kg/h — main-stream feeding |
| Gain-in-Weight (GIW) | Weighs the receiving vessel rather than the feeder | Batching into mixers and reactors |
Available Options
| Option | Choices |
|---|---|
| Mode | Loss-in-weight (L) · Batching / GIW (B) · Volumetric fallback (V) |
| Dosing element | Single screw · Twin screw · Vibratory tray · Weigh belt |
| Size index | 18 · 37 · 70 · 85 · 120 |
| Mounting | Platform (P) · Suspended / hanging (H) |
| Hopper shape | Asymmetric (A) · Symmetric (S) · Cylindrical (C) |
| Hopper volume | 50 – 1,400 litres |
| Screw geometry | Auger (AG) · Concave (CC) · Spiral (SP) |
| Drive | Servo (SV) · Gear motor (GM) |
| Refill | Manual · Automatic valve · Vacuum receiver |
| Safety | Standard · ATEX |
Technical Specification
| Parameter | Unit | Range |
|---|---|---|
| Feed rate | kg/h | 0.4 – 5,000 |
| Rate accuracy | % of rate | ±0.5 – ±1 |
| Turndown ratio | — | 10:1 – 20:1 standard, up to 100:1 twin screw |
| Refill share of running time | % | Typically below 10 |
| Response to set-point change | s | Seconds to tens of seconds |
| Load cells | pcs | 3 – 4, OIML R60 C3 |
| Hopper volume | litre | 50 – 1,400 |
| Contact part material | — | SS304 · SS316 |
| Hazardous area | Zone | 20 / 21 / 22 on request |
Areas & Application
Plastics & Compounding
Feeding additives, masterbatch and fillers into extruders at controlled ratio, where a percentage error becomes an out-of-spec compound.
Dry Mortar & Construction Chemicals
Component feeding into continuous mixers, where the final recipe ratio is the direct result of feeder accuracy.
Animal Feed & Aquaculture
Micro-ingredient and premix dosing into continuous and batch mixing lines.
Food Processing
Ingredient feeding in sanitary execution with recipe management and batch traceability.
Chemicals
Continuous reactor and process feeding under ATEX conditions where dust is combustible.
Petrochemicals
Catalyst, additive and polymer dosing under recipe control, with batch records for process traceability.
Options & Compliance
- MaterialsSS304 · SS316 for product-contact parts
- Hazardous areaATEX execution for Zone 20 / 21 / 22
- EnclosureIP55 standard · IP65 washdown
- Control interfaceProfinet · Modbus TCP · EtherNet/IP with recipe management and rate logging
- StandardsOIML R60 C3 load cells · FDA CFR 21 and EU 1935 for food contact · ATEX 2014/34/EU · ISO 12100
Send us your material, nominal rate and minimum-to-maximum range — we will size the feeder and confirm achievable accuracy.