Internal diameter determination in conical glassware: A comparative analysis of measurement methods

This study investigates internal diameter determination in conical graduated volumetric instruments by comprehensively comparing three measurement methods: vernier calliper, optical comparator, and height gauge. Unlike international standards, which offer a single internal diameter value valid for cylindrical volumetric instruments, conical glassware presents different volumes between graduations and multiple internal diameter values. The research underscores the significance of accurate internal diameter determination in minimizing meniscus reading uncertainty during gravimetric calibration. The paper references a novel optical comparator method, achieving a maximum 2 % error in the meniscus uncertainty. However, acknowledging limitations and cost concerns, it explores two alternative measurement methods: vernier calliper or height gauge. Vernier calliper is cheaper and easier, but the height gauge is effective, relatively low-cost, and especially useful when vernier calliper measurements are impossible. The study contributes valuable insights into comparing these methods for the first time, emphasizing their applicability in diverse conical glassware scenarios.