Uncertainty Analysis and Evaluation of Measurement Results for Suspended Container Weighing Device

The suspended container weighing device adopts the principle of moment balance. It determines the total mass and centroid coordinates of a container by measuring the mass values at the four lifting points of the container. As a common measuring instrument widely used in port terminals, logistics hubs and other sites, the accuracy of its measurement results is critical for overload prevention, eccentric load early warning of container transportation, and the fairness of trade settlement. JJF 2285-2025 Calibration Specification for Suspended Container Weighing Devices specifies the calibration methods for the indication error of mass and the indication error of container centroid coordinates of suspended container weighing devices. This paper analyzes and evaluates the measurement uncertainty thereof.

1 Measurement Basis and Methods

1.1 Measurement Basis

JJF 2285-2025 Calibration Specification for Suspended Container Weighing Devices.

1.2 Unit under Test

Suspended container weighing device.

1.3 Measurement Standard

Standard weights with a nominal value of 500 kg, accuracy class M1, quantity: 20 pieces.

1.4 Measurement Methods

1.4.1 Indication Error of Mass

Ensure the weighing device is under no-load condition, inspect and zero-set the instrument. Starting from zero load, add standard weights up to near the maximum weighing capacity, then unload the standard weights back to zero. Take three measurements at each weighing point. Unloading of standard weights is permitted during measurement; after unloading, the zero point shall be checked. If the zero indication is non-zero, the indication shall be reset to zero.

1.4.2 Indication Error of Centroid Coordinates

Divide the container plane into four zones A, B, C and D. Connect the container to the weighing device. Place the centroid standard artifact at at least one position within Zone A according to the operating conditions of the weighing device. Start the weighing device and perform zero setting. Place the centroid standard artifact at the selected position and carry out three repeated measurements. Repeat the above measurement procedure for Zone B, Zone C and Zone D respectively. This evaluation takes Zone A as an example.