InterProcess Sp. z o.o. | Rozwiązania dla przemysłu
What hopper weighing is
Direct mass measurement instead of estimating a level
Hopper scales — also known as silo scales, vessel weighing kits or hopper weighing systems — measure mass directly rather than a level converted into a volume. Unlike capacitive, radar or ultrasonic probes, the gravimetric method needs no knowledge of density, dielectric constant or the speed of sound in the medium, and is undisturbed by dust, foam, bridging or caking.
At InterProcess we engineer every hopper scale individually, for new and existing vessels alike. Load cells are fitted directly into the vessel supports, together with the appropriate load-transfer components, bump stops, tie rods and a weighing terminal. When upgrading an existing installation, bolt-on strain sensors can be used instead — mass measurement without touching the structure of the vessel.
Operating principle
From the load cell in the support to the mass reading
A typical silo scale comprises load cells fitted into the vessel supports, mounting kits (weigh modules) that transfer the load correctly, a signal summing box and a weighing terminal (integrator). The load cells — most often shear-beam or compression types — generate an electrical signal proportional to the load.
The signals from all the load cells are summed and then converted by the weighing terminal into a mass reading in kilograms or tonnes, which is also available in the plant’s higher-level system.
Diagram of a hopper weighing system — the signals from the load cells in the supports are summed in the junction box and converted by the weighing terminal into a mass reading.
What determines accuracy
The key to a hopper scale working properly is eliminating side forces, which can arise from rigid connections between the vessel and pipework, ventilation ducts or other parts of the installation. Suitable weigh modules with load-transfer components, bump stops and tie rods compensate for these forces.
- Side force compensationflexible expansion joints on the connections, bump stops and tie rods in the modules
- Load cell classcapacity and accuracy class selected for the specific application
- Calibrationthe quality of system calibration after installation and in service
- Supporting structurestability of the supports and correct load transfer into the cells
System components
What a vessel weighing kit consists of
Every weighing kit is engineered individually — around the shape of the vessel feet, the ambient conditions and the accuracy required.
Upgrading without touching the structure — strain sensors
We engineer weighing kits for newly built and existing vessels alike. The mounting plates are matched to the shape of the vessel feet, so installation calls for no structural rebuilding.
Where modifying the supports is impossible, we use bolt-on strain sensors. They are bolted to a leg or a supporting beam and measure the deflection of the structure caused by the change in mass — with no structural alterations and without emptying the vessel for installation and calibration. Accuracy is lower than with a full weighing kit (inventory-control class rather than trade class) and depends on the stress level in the support and on the influence of temperature and wind; where requirements are higher we therefore fit two sensors per support with thermal compensation.
Ask about upgrading your vessel
Strain sensors are fitted to the structural sections of the vessel — one or two per support, without touching the structure.
Weighing vs level measurement
Which measuring method should you choose?
Level probes — radar, ultrasonic or capacitive — measure the height of the material and convert it into a volume; the result depends on the bulk density, the geometry of the vessel and the behaviour of the medium. A hopper scale measures mass directly, the quantity that actually matters in production and in trade settlement.
| Parameter | Hopper scale gravimetric | Level measurement radar · ultrasonic · probes |
|---|---|---|
| Measured quantity | Mass — directly, in kg or tonnes | Level → converted into volume and mass |
| Dependence on the properties of the medium | ✓ None — powder, granulate, liquid or gas | ✗ Requires density, dielectric constant or speed of sound |
| Dust, foam, bridging | ✓ No effect on the measurement | ✗ Disturb the probe reading |
| Surface cones and caking | ✓ Irrelevant — mass is mass | ✗ Falsify the level reading |
| Intrusion into the vessel | Fitted in the supports — no openings in the shell; strain sensors optional | A mounting nozzle in the roof or wall of the vessel |
| Batching and balancing | ✓ Weighing out batches, recording intake and discharge | ✗ Indicative fill level only |
| Capital cost | Higher — load cells, modules and terminal | Lower — a single probe |
| When to choose it? | Balancing, batching, recipes, trade settlement, difficult materials | Indicative level monitoring of homogeneous, easy-flowing media |
Functions and operating modes
From inventory control to automatic batching
The range of functions depends on the controller used and the configuration of the system — from a simple mass readout to fully automatic batching.
Continuous mass measurement
A constant reading of how full the vessel is — the basis of raw material inventory control.
- —mass displayed on the terminal and in the higher-level system
- —minimum and maximum level alarms
- —automatic order generation when stock reaches the minimum
Balancing intake and discharge
Taking material in and issuing it while recording the quantities — full control of raw material flow through the vessel.
- —recording of the quantities received and issued
- —archiving of data on changes in mass
- —production and settlement reports
Weighing out and batch dosing
Automatic weighing out and dosing of set batches of material — the vessel becomes part of the batching system.
- —measuring out set batches in batch mode
- —control of valves, feeders, slide gates and pumps from the terminal
- —support for multi-ingredient recipes
Integration with the plant automation
The scale as part of the plant’s process automation
Communicating with higher-level control systems (PLC, SCADA) makes the silo scale an integral part of the process automation: it allows data on changes in mass to be archived, production reports to be generated and vessel contents to be monitored remotely. Modern weighing terminals drive the final control elements — valves, feeders, slide gates and pumps — directly, without an additional controller in between.
Modbus RTU / TCP
Profibus
EtherNet/IP
analogue and relay outputs
If your application calls for precise dosing with active flow control, take a look at our gravimetric screw feeders and our belt weighfeeders.
System selection
Which vessels do we design scales for?
Practically every type of industrial vessel. The type of vessel determines the choice of load cells, the mounting kits and the way side forces are compensated.
| Type of vessel | Typical medium | Key selection factors |
|---|---|---|
| Storage vessels and silos | bulk materials, granulates, powders — from a few hundred kilograms to over 100 tonnes | load cell capacity, tie rods and bump stops on outdoor silos (wind loading) |
| Process vessels and mixers | recipe ingredients, blends | compensation of dynamic forces from agitators and vibrators |
| Chemical reactors | reagents, aggressive media | flexible connections on pipework and heat exchangers |
| Liquid tanks | milk, chemical liquids, fuels | corrosion-resistant materials, hygienic build |
| Feed hoppers and feeders | part of gravimetric batching systems | high resolution and fast dynamic response — in loss-in-weight feeders, for example |
Industries and applications
Industrial applications of hopper scales
🍞 Food and animal feed industries
Raw material inventory control in silos — flour, grain, sugar, animal feed — and batching of recipe ingredients into mixers.
⚗️ Chemical and pharmaceutical industries
Precise balancing of reagents, monitoring of contents in reactors and quality control of the production process.
🏗️ Construction and cement industries
Weighing kits beneath silos for stock control of cement, lime and aggregates.
📦 Logistics and warehousing
Automatic stock monitoring and order generation when material reaches the minimum level.
FAQ
Frequently asked questions
Why InterProcess
Why choose our solutions?
Individually engineered
Every silo scale is designed around the customer’s particular vessel.
End-to-end delivery
From load cell selection through to installation, calibration and service.
Proven components
Load cells from reputable manufacturers.
Experience across many industries
Food, chemical, pharmaceutical and construction.
Safety and hygiene
Systems compliant with ATEX, HACCP and GMP.
Technical support and service
With a fast response, including 24/7 cover.