Development of a New, High Sensitivity 2000 kg Mechanical Balance

Area of Science:

• Metrology
• Mechanical Engineering
• Instrumentation

Background:

• Electronic mass comparators struggle with repeatability and linearity for mass measurements exceeding 500 kg.
• Calibration requirements for Class F1 weights in sectors like pharmacy and power generation necessitate higher precision for large masses.

Purpose of the Study:

• To introduce a novel 2000 kg mechanical balance designed for precise mass measurement above 500 kg.
• To detail the advantages and innovative features of the new mechanical balance for industrial applications.

Main Methods:

• Development of a 2000 kg mechanical balance by the National Institute of Metrology (NIM).
• Utilizing four vertical forces for beam position adjustment to achieve high measurement uncertainty.
• Incorporating laser displacement sensors to minimize human reading errors.
• Implementing a synchronous lifting control for enhanced repeatability and sensitivity.
• Designing a counterweight selection system for flexible weight combinations.

Main Results:

• The new mechanical balance demonstrates superior performance for mass measurements over 500 kg.
• Sensitivity of the 2000 kg balance exceeds 1.7 x 10^-4 rad/g.
• Extended uncertainties for 500 kg, 1000 kg, and 2000 kg measurements are 0.47 g, 1.8 g, and 3.5 g, respectively.

Conclusions:

• The NIM's 2000 kg mechanical balance effectively addresses the limitations of electronic comparators for heavy mass calibration.
• The innovative design features significantly improve measurement accuracy, repeatability, and sensitivity.
• This development provides a reliable solution for critical industrial calibration needs in pharmacy and power generation.