Load cells are components used in weighing systems to measure the weight of a material or the force applied to a structure. In industrial applications, they are used with different types of equipment, including vertical silos, inline hoppers, tanks and material dosing systems.
When installed on a silo or hopper, load cells make it possible to determine the quantity of product contained by measuring its weight. This information can be used to monitor stock levels, schedule loading and discharge operations, manage dosing or integrate weighing into the production process.
Poggi designs and manufactures bulk material storage systems that can be configured with weighing systems selected according to the material, required capacity and specific operational requirements.
What are load cells?
A load cell is a transducer, meaning a device that converts a mechanical force into a measurable electrical signal.
When subjected to a load, the cell undergoes an extremely small deformation. The sensing elements inside the device detect this change and generate a signal proportional to the applied force.
The signal is then processed by a weight indicator or control system and converted into a readable value. This makes it possible to determine the weight of the material contained inside a silo, hopper or other industrial container.
What are load cells used for?
Load cells make it possible to measure weight continuously or at specific stages of a process. Their function is therefore not limited to displaying a value: they can support the management of different operational phases.
In a system designed for storing and handling bulk materials, load cells can be used to:
- determine the quantity of material available;
- monitor container filling;
- track product consumption;
- schedule material replenishment;
- measure the quantity discharged;
- manage dosing processes;
- detect unexpected weight variations;
- transmit data to control systems.
A weighing system can therefore provide useful information during both the loading and utilisation of the stored material.
How do load cells work?
In industrial applications, load cells are generally positioned at the supporting points of the structure to be weighed. The load is distributed across the different cells, each of which measures part of the force exerted by the total weight.
The signals generated by the cells are collected and processed to determine the total weight. By subtracting the weight of the empty structure, known as the tare weight, it is possible to calculate the actual quantity of material contained.
A weighing system generally consists of:
- one or more load cells;
- mounting and load distribution components;
- signal connection devices;
- a weight indicator or transmitter;
- control and automation systems, where required.
The configuration must be defined according to the structure, capacity, number of supporting points and conditions under which weighing takes place.
Load cells for silos
Load cells for silos make it possible to determine the quantity of stored material by weighing the entire structure. They are generally installed beneath the supporting points of the silo. Each cell measures part of the load, and the combined measurements are used to calculate the total weight.
This solution can be used with different bulk materials, including cement, lime, fly ash, premixed products, flour, granules, additives and other powdered or granular products.
Weighing a silo can be useful for:
- determining the actual quantity of material available;
- monitoring the quantities loaded and withdrawn;
- planning material supplies;
- preventing interruptions caused by product shortages;
- integrating weight data into production processes;
- monitoring material consumption.
Load cells are among the main silo accessories used to adapt a storage system to specific material monitoring and management requirements.
Load cells and level indicators: what is the difference?
Load cells and level indicators perform different functions, although both contribute to monitoring the material contained inside a silo.
Level indicators generally detect when the material reaches a specific height or measure the distance between the sensor and the surface of the product. They can be used to indicate minimum, maximum or intermediate levels.
Load cells measure the weight exerted by the silo and the material it contains. The result does not depend directly on the shape or distribution of the product inside the container.
The choice between the two systems depends on the information required. In some configurations they can be used together: level indicators monitor specific filling thresholds, while load cells measure the total weight.
Load cells for hoppers
Load cells can also be applied to hoppers used to receive, temporarily store and discharge bulk materials.
In this case, weighing makes it possible to determine the quantity loaded into the hopper or measure the material released during discharge. The data can be used to monitor individual batches, feed subsequent processing stages or manage dosing operations.
In hoppers equipped with loss-in-weight systems, the quantity delivered is determined by measuring the reduction in weight during discharge. This principle makes it possible to control the material transferred to conveyor belts, elevators, mixers or other downstream equipment.
Poggi manufactures hoppers that can be configured with load cells and control systems according to the characteristics of the material and the required loading, weighing and discharge methods.
What are the advantages of weighing with load cells?
Quantity monitoring
Weight measurement makes it possible to determine the quantity of material available and monitor changes during use.
Stock management
Continuous monitoring helps schedule material supplies and reduces the risk of interruptions caused by product shortages.
Material dosing
In processes requiring defined quantities, weight data can be used to manage dosing and control the amount of material discharged.
Integration with control systems
The measured values can be transmitted to indicators, control panels or supervision systems, making the information required to manage the process readily available.
Use with different materials
Load cell weighing can be used with many powdered or granular materials, provided that the system is correctly sized according to the structure and operating conditions.
What factors can affect weighing accuracy?
To obtain reliable measurements, selecting the nominal capacity of the load cells is not sufficient. The complete configuration of the structure must also be considered.
The main factors to evaluate include:
- the empty weight of the silo or hopper;
- the maximum quantity of material;
- the number and position of supporting points;
- correct load distribution;
- possible vibrations;
- rigid connections to other equipment;
- loads caused by wind or environmental conditions;
- temperature and installation-site characteristics;
- the methods and frequency of loading and discharge operations.
Pipes, walkways and mechanical connections must be considered during the design stage because they can transfer forces to the structure and affect the measurement.
How do you select load cells for a silo or hopper?
The selection process must begin with the capacity of the structure and the required level of accuracy, while also considering the material, process and operating conditions.
The following factors should be evaluated:
- the maximum expected load;
- the tare weight of the structure;
- the type of application;
- the number of load cells required;
- environmental conditions;
- the presence of vibrations or lateral loads;
- the frequency of operations;
- the required control and display system;
- possible integration with other systems.
There is therefore no universal configuration. The weighing system must be sized together with the silo or hopper so that the structure, load cells and control components operate in a coordinated manner.
Weighing can also be coordinated with the systems used to extract the material from the structure. For more information about this stage, read How is a silo emptied?.
Weighing systems for Poggi silos and hoppers
Weighing should be considered during the design of the storage and handling system, together with the methods used to load, contain and discharge the material.
Poggi develops silos and hoppers that can be configured with load cells, indicators and control systems according to the characteristics of the product and specific operational requirements.
The solution is defined by analysing the material, required capacity, available space and the process into which the product must be integrated. This approach makes it possible to develop a configuration that meets the actual storage, monitoring and dosing requirements.
To evaluate the most suitable configuration for a specific application, contact Poggi.
Frequently asked questions about load cells
What do load cells measure?
Load cells measure the force exerted by a weight. The generated signal is processed and converted into a value that can be used by the weighing system.
How is the material contained in a silo weighed?
A silo can be supported by multiple load cells installed at its supporting points. The weight of the empty structure is subtracted from the total measurement to determine the quantity of material contained.
Can load cells be used with hoppers?
Yes. They can measure the material loaded into a hopper or the quantity discharged, including through loss-in-weight weighing systems.
What is the difference between a load cell and a level sensor?
A load cell determines the quantity of material through its weight, while a level sensor detects the presence or height of the material. The two technologies can also be used together.
Are load cells suitable for all silos?
The possibility of installing load cells depends on the structural characteristics, capacity, supporting points and operating conditions. The system must therefore be evaluated and sized for the specific application.
