What are the calibration methods for electronic belt scales? What is the correct calibration process?

Electronic belt scales are dynamic weighing instruments used on belt conveyors. During operation, they may be affected by various factors such as the surrounding environment, belt conveyors, mechanical vibration, and belt tension.

After a period of use, the accuracy of electronic belt scales may decrease, and the zero point may become inaccurate, unable to match the precision achieved during initial calibration.

To maintain the accuracy of electronic belt scales, regular calibration and verification are essential during daily use. There are various methods for calibrating electronic belt scales, each following specific procedures.

1. Calibration Methods for Electronic Belt Scales

   Common calibration methods for electronic belt scales include: hanging weight calibration, chain weight calibration, and actual material calibration.

  （1）Hanging Weight Calibration: This method involves hanging standard weights on the weighing bridge of the electronic belt scale to simulate the weight data of material during operation. It is low-cost, easy to operate, and requires minimal space, but the calibration accuracy is low, making it unsuitable for high-precision measurements.

   （2）Chain Weight Calibration: This method involves placing standard chain weights on the belt to simulate the material passing state. Chain weight calibration is a commonly used method for electronic belt scales. It features various chain weight devices, such as winch chain weights and circulating chain weights, which can be stored when not in use and deployed for calibration. It offers high accuracy, low cost, high automation, and easy operation, with different devices selectable based on actual working conditions.

   （3）Actual Material Calibration: This method directly uses the actual conveyed material for calibration, providing the highest accuracy. However, it requires a large calibration space, is costly, and involves cumbersome operations. Many electronic belt scales cannot undergo actual material calibration due to space limitations and other conditions.

2. Calibration Process for Electronic Belt Scales

   To maintain the accuracy of electronic belt scales, they must be calibrated following the correct procedures. Generally, if not using actual material calibration, the calibration interval should not exceed 10 days. If using actual material calibration, it should be performed monthly. Of course, this may vary based on specific on-site applications. If there are operations such as maintenance or belt replacement, re-calibration is required.

   Using the commonly used circulating chain weight as an example, the calibration process for electronic belt scales is as follows:

   - (1) Before starting the calibration of the electronic belt scale, ensure that the scale and circulating chain weight are functioning normally and that the belt scale can operate correctly.

   - (2) Before calibration, run the belt empty for 5 minutes to confirm smooth operation and perform zero-point calibration, then record the results.

   - (3) After zero-point calibration, stop the belt conveyor. Once stopped, lower the chain weight to the center of the belt.

   - (4) After placing the chain weight, start the belt conveyor. Personnel on-site should check for normal operation and immediately stop the conveyor if any issues arise.

   - (5) After calibration, stop the belt conveyor. Once stopped, record the data on the instrument, retract the chain weight, and compare the actual weight with the weight displayed on the instrument to assess the accuracy of the electronic belt scale.