For many production sites, the contents of a tank, silo or vessel represent a significant investment. If inventory is estimated rather than measured, you may be carrying more stock than necessary, ordering materials too late or losing product through overfilling, inaccurate batching and process variation.
A correctly designed tank weighing system gives you a continuous view of material held in the vessel. It can support stock control, production planning, batching and process automation while helping your team identify problems before they affect output.
This guide explains how load-cell based tank and silo weighing works, what to consider when selecting a system and how WOMAG can support you from initial design through to calibration and ongoing maintenance.
How does tank and silo weighing work?
A tank weighing system measures the total weight of the vessel and its contents. Load cells are installed beneath the tank legs, silo supports or vessel mounting points. As material is added or removed, the load cells detect the change in force and transmit a signal to weighing electronics.
A typical system includes:
- Three or four load cells, depending on the vessel design and number of support points
- Weigh modules or mounting kits to manage movement and protect the cells
- A junction box or digital summing system
- A weight indicator, transmitter or process controller
- Connections to a PLC, SCADA, MES or other control system
Compression load cells are commonly used beneath supported tanks and silos. Tension load cells can be suitable for suspended vessels, while shear beam load cells are often used for smaller tanks, hoppers and process vessels.
The system measures mass directly. This is useful because the result does not depend on the shape of the tank or the surface condition of the material. For example, dust, foam, changing material geometry or uneven product distribution can make some point level technologies difficult to interpret. Weighing the complete vessel provides a direct indication of how much material is present.
If you need to estimate volume or physical level, the measured mass can be converted using known density information. In many applications, however, weight-based stock monitoring is the more useful measurement because materials may settle, bridge or change density during storage.
What can real-time inventory monitoring help you achieve?
Reduce waste and product giveaway
Accurate weight data helps you control how much material enters or leaves a process. This is particularly valuable where ingredients, liquids, powders or chemicals are expensive, or where excess material cannot be recovered easily.
For example, weight-based filling and dosing can help you stop a fill at a defined target rather than relying only on flow time or volume. In a gravimetric filling system, programmable controllers can use target weights, tolerance bands and automatic cut-off points to support consistent filling.
The same principle can apply to blending, batching and loss-in-weight feeding. By measuring the change in vessel weight over time, the control system can calculate material usage and help regulate the feed rate.
Improve stock control
A live inventory reading gives your production and purchasing teams a more reliable view of available material. You can monitor minimum stock levels, identify unusual consumption and plan replenishment using measured data rather than manual estimates.
This can be especially useful where materials are stored in several tanks or silos. A central dashboard can show the current weight of each vessel, helping operators understand which materials are available and which require attention.
Support process consistency
Consistent material quantities help your process produce repeatable results. In food and beverage, this may support recipe control. In chemical manufacturing, it can help maintain the required formulation. In pharmaceutical production, accurate material measurement can contribute to controlled and documented processing.
A tank weighing system can provide the measurement used to trigger valves, pumps, conveyors and other equipment. Your control system can then respond to defined weight values, such as a low-level warning, a target batch weight or an overfill limit.
Strengthen traceability and compliance
Weight data can be logged alongside batch, product and production information. This provides a record of material receipts, usage and transfers, depending on how the system is integrated.
Where weighing forms part of a quality-controlled process, regular calibration and documented maintenance help demonstrate that the equipment remains suitable for its purpose. WOMAG provides traceable calibration services, including onsite and offsite options for equipment from a range of manufacturers.
What should you consider when choosing a tank weighing system?
1. How many load cells are required?
As a general starting point, you normally need one load cell for each structural support point. A three-legged vessel may use three cells, while a four-legged tank or hopper will often use four.
Three-point support can simplify load sharing because the system is less mechanically over-constrained. Four-cell systems are also widely used, particularly for rectangular vessels and larger hoppers, but they need suitable balancing and installation checks.
The final arrangement depends on:
- Tank or silo geometry
- Number and position of support legs
- Total vessel and material weight
- Structural loading
- Required accuracy
- Available installation space
- Environmental and safety requirements
The load cell capacity must include the empty vessel, maximum product load, attached equipment and an appropriate allowance for uneven loading or dynamic forces. All cells within the system should normally be matched for type, capacity and output.
2. What level of accuracy do you need?
The correct accuracy target depends on the application. Basic inventory monitoring may not require the same performance as precision batching or legally controlled weighing.
When discussing your requirements, consider whether the system will be used for:
- General stock indication
- Replenishment and low-level alarms
- Recipe batching
- Dosing or loss-in-weight control
- Product transfer records
- Trade or chargeable measurements
Accuracy is affected by more than the load cell specification. Rigid pipework, uneven foundations, vibration, temperature changes and external structures can all influence the result.
Flexible connections are often required so that pipes, ducts and hoses do not restrict the vessel’s movement or carry part of its weight. Mounting arrangements should also protect the load cells from excessive lateral forces and provide suitable lift-off or restraint protection where required. HBK’s guidance on tank weighing system design provides further technical background on these mechanical considerations.
3. Will the equipment be used in a hazardous area?
If your process involves flammable liquids, vapours, gases or combustible dust, the weighing system must be specified as part of the site’s hazardous-area protection strategy.
You may need ATEX-certified load cells, junction boxes, indicators, barriers and associated electrical equipment. The certification must match the relevant zone and the conditions of use. It is also important to remember that certification may apply to individual components. For example, a multi-cell tank system may require an individual ATEX certificate for each load cell.
WOMAG supplies ATEX weighing equipment, including ATEX-certified compression load cells for tank and hopper applications. The Dini Argeo ATEX CPX load cell is available in a wide range of capacities and is designed for demanding industrial environments.
Our team can review your zone classification, product characteristics and control requirements before recommending a suitable configuration. Final selection should always be confirmed against your site risk assessment and applicable hazardous-area requirements.
4. How will the system connect to your controls?
A tank weighing system becomes more useful when its data is available where your operators and control systems need it.
Depending on the equipment selected, the weighing transmitter may connect to a PLC or SCADA system using analogue signals or an industrial communications protocol. The system can then provide:
- Live tank or silo weight
- Low-level and high-level alarms
- Batch targets and cut-off signals
- Rate-of-change information
- Material usage records
- Data for production, MES or ERP systems
WOMAG supplies process control weighing equipment and can help integrate weighing into wider automation arrangements. We will consider your existing controls, preferred communications method and the level of operator information required.
How do you maintain accuracy after installation?
Installation is only one part of achieving dependable tank weighing. The structure, load cells, weighing electronics and mechanical connections should be checked as part of a planned maintenance programme.
Calibration intervals depend on the criticality of the application, site procedures, operating conditions and quality requirements. A suitable calibration programme may include:
- Initial calibration after installation
- Repeatability and corner-load checks
- Inspection of load cell mounts and cables
- Checks for pipework or structures affecting the vessel
- Verification of alarms and control signals
- Periodic recalibration using traceable equipment
Changes to the vessel, pipework, agitators, supports or control system may require additional checks. If the equipment is used in a washdown, corrosive or dusty environment, routine inspections can also help identify damage before it affects measurement performance.
WOMAG can provide servicing, repairs and preventative maintenance for weighing equipment supplied by us or another manufacturer. Our maintenance plans can combine service, repair and calibration, with onsite support arranged to minimise disruption to your operation.
How can WOMAG help with tank and silo weighing?
We can help you assess the complete application rather than selecting load cells in isolation. Our team can review:
- Vessel size, shape and support arrangement
- Product type, density and operating temperature
- Required weighing capacity and accuracy
- Pipework, mixers, pumps and other connections
- Hazardous-area classification
- Existing PLC, SCADA, MES or ERP systems
- Calibration, servicing and access requirements
We supply, install, calibrate and maintain tank, silo and vessel weighing systems for food and beverage, chemical, pharmaceutical and general manufacturing applications. Where required, we can also support associated process control, filling and automation equipment.
If you are planning a new installation, upgrading an existing system or investigating inconsistent inventory readings, contact the WOMAG team for practical advice. Share your vessel capacity, product, support arrangement and required accuracy, and we can help you identify a suitable next step.