Mastering Belt Scale Calibration in Quarries: Test Weight vs Material Test

Accurate measurement of material flow in quarries and mines is essential for operational efficiency and cost control. Conveyor belt scales play a critical role in tracking production. However, without proper belt scale calibration, these measurements can drift, leading to costly errors. This post explores two key calibration methods—test weight calibration and material test calibration—and explains how to apply them effectively to maintain precision in your quarry operations.

Calibrating an HQ Quad Heavy Duty conveyor belt scale

Understanding Belt Scale Calibration

Belt scale calibration ensures that the belt scales provide accurate readings of the material passing over the belt. Over time, factors such as belt tension, environmental conditions, and mechanical wear can affect the scale’s accuracy. Regular calibration is necessary to detect and correct these deviations.

Two main calibration methods are used in the field:

• Test Weight Calibration

• Material Test Calibration

  
  

Each method serves a distinct purpose and offers different levels of accuracy.

Test Weight Calibration: Quick Accuracy Checks

Test weight calibration involves placing a known weight on the conveyor belt scale to verify the load cell readings. This method is straightforward and useful for spot checks or confirming that the scale is functioning correctly between more thorough calibrations.

Test weight calibration on an HQ Scales Rocket belt scale installed on a stacking conveyor in a quarry

How It Works

• A certified test weight is placed on the belt scale.

• The scale reading is compared to the known weight.

• A calibration adjustment is made to calibrate the scale to the test weight amount.

• Any discrepancy indicates a need for adjustment or further investigation.

  
  

When to Use Test Weight Calibration

• After the initial belt scale installation.

• To confirm scale accuracy during routine inspections.

• When troubleshooting suspected scale errors.

• As a quick check before critical operations.

• After moving the conveyor to a new location.

  
  

Advantages and Limitations

Advantages:

• Simple and fast to perform.

• Requires minimal equipment.

• Good for identifying errors.

  
  

Limitations:

• Does not account for dynamic factors like belt tension.

• Less accurate than material test calibration.

• Not suitable for high accuracy calibration adjustments.

  
  

Test weight calibration is a valuable tool for maintaining confidence in your conveyor scales but should not replace more comprehensive calibration methods.

Material Test Calibration: The Gold Standard

Material test calibration compares the belt scale’s readings against a certified scale such as a legal for trade truck scale. This method provides the highest accuracy and accounts for real-world conditions affecting the belt scale.

Truck enroute to a certified truck scale to be weighed

How It Works

• Material is passed over the belt scale while being loaded into a waiting truck. The truck then is weighed on a legal for trade truck scale. The belt scale value is compared to the truck scale value.

• Multiple tests (usually three) are conducted to ensure repeatability.

• The total belt scale weights are added and the total certified weights are added. These values are entered into the HQ Scales integrator and the calibration value is calculated automatically.

• After the calibration adjustment is made, another truck test may be performed to confirm scale performance.

  
  

Why It Matters

Material test calibration eliminates errors caused by factors such as:

• Belt tension variations

• Stringline alignment errors

• Incorrect idler spacing measurements

• Conveyor fluctuations

  
  

By calibrating with an actual known weight, this method ensures the belt scale reflects true operational conditions.

When to Perform Material Test Calibration

• At least once every quarter, as part of a regular maintenance schedule.

• After major repairs or belt replacements.

• After moving the conveyor to a new location.

  
  

Benefits of Material Test Calibration

• Provides the most accurate and reliable scale readings.

• Improves operational decision-making based on precise data.

• Reduces errors in loadout applications.

  
  

Best Practices for Belt Scale Maintenance and Calibration

Calibration alone is not enough to guarantee accurate measurements. Proper belt scale maintenance is essential to keep the system functioning optimally.

Maintenance Tips

• Regularly inspect the belt scale for mechanical wear or damage.

• Keep the scale clean and remove rock buildup and debris.

• Check belt tension and alignment frequently.

• .Ensure scale idlers are in working order and properly aligned.

  
  

Calibration Schedule

• Perform material test calibration quarterly.

• Use test weight calibration monthly or as needed for spot checks.

• Document all calibration activities for traceability.

  
  

Choosing the Right Belt Scale for Your Quarry

Selecting a reliable belt scale with a user-friendly interface simplifies calibration and maintenance tasks. HQ Scales offers top-of-the-line conveyor scales designed for rugged quarry environments. The HQ belt scale integrator provides clear calibration prompts and easy data access, helping technicians and managers maintain accuracy with less effort.

HQ Scales' Integrator Webpage. Standard with every scale.

Summary

Accurate belt scale calibration is vital for quarry operations to measure material flow correctly and avoid costly errors. Test weight calibration offers a quick way to verify scale accuracy, while material test calibration provides the most precise adjustment by comparing actual material weights. Combining these methods with regular belt scale maintenance ensures your conveyor scales deliver reliable data.

For more information regarding the Test Weight and Material Test Calibration check out this video: https://youtu.be/MaHpMrgBPJM?si=6SkGIq2VlrmoqV94