Understanding Silo and Vessel Calibrations

In industries where precise measurement is crucial, such as food processing, pharmaceuticals, and chemical manufacturing, the accuracy of silo and vessel weighing systems is incredibly important. Regular calibration of the load cells ensures that these systems provide reliable data, leading to improved product quality, reduced waste, and enhanced safety. But how do you calibrate large silos and vessels safely and efficiently?

Traditional methods of calibration involved physically adding known weights to the vessel or silo. This approach, while effective, can be time-consuming, costly, and potentially hazardous, especially with large-capacity systems. Thankfully, modern technology offers safer and more practical alternatives: signal injection and force compensation.

Signal Injection: Simulating Weight Electronically

Signal injection, often performed using a process calibrator, involves injecting a simulated electrical signal into the load cell’s circuitry. This method bypasses the need to physically apply weight. The process calibrator generates a precise electrical signal that mimics the output of the load cell under a known load. By comparing the injected signal with the system’s displayed weight, technicians can assess and adjust the calibration.

This technique is particularly useful for routine checks and adjustments, as it’s quick and efficient. However, it’s important to note that signal injection verifies the electronic components of the weighing system but doesn’t test the mechanical integrity of the vessel or its supports.

Force Compensation: Using Hydraulic Jacks and Reference Load Cells

For a more comprehensive calibration, force compensation using hydraulic jacks and reference load cells is often preferred. This method involves applying a known force to the vessel using hydraulic jacks while monitoring the force with highly accurate reference load cells.

Here’s how it works:

• Hydraulic Jacks: These are placed strategically under the vessel’s supports.
• Reference Load Cells: These high-precision load cells are placed between the hydraulic jacks and the vessel structure.
• Force Application: The hydraulic jacks apply a controlled force, which is measured by the reference load cells.
• System Comparison: The readings from the reference load cells are compared to the readings from the vessel’s load cells. Any discrepancies are then adjusted.

This method provides a more accurate representation of the system’s performance under actual loading conditions and is especially useful for verifying the mechanical integrity of the vessel and its supports. It offers a safe alternative to adding large amounts of weight, reducing the risk of accidents and damage.

Why These Methods Are Safer Alternatives

Both signal injection and force compensation offer significant safety advantages over traditional mass application methods:

• Reduced Risk of Injury: Eliminating the need to handle heavy weights minimises the risk of lifting injuries and accidents.
• Minimised Structural Stress: Applying controlled forces with hydraulic jacks reduces the risk of over stressing the vessel or its supports.
• Increased Efficiency: These methods are typically faster and more efficient than adding physical weights, reducing downtime and costs.
• Improved Accuracy: Reference load cells provide highly accurate measurements, ensuring reliable calibration results.

Choosing the Right Calibration Method

Selecting the appropriate calibration method depends on several factors, including the size and type of the vessel, the required accuracy, and the available resources. If you’re unsure which method is best for your specific needs, it’s always advisable to consult with an MWS process weighing specialist. We can assess your system and recommend the most suitable and safe calibration approach, ensuring your processes remain accurate and efficient.