MasseStandards

Mass standards are physical objects or definitions used to represent a unit of mass. They are essential for accurate measurement and calibration of scales and other weighing instruments. The most fundamental mass standard is the kilogram, which is defined by the International System of Units (SI). Historically, the kilogram was defined by a physical artifact, the International Prototype Kilogram (IPK), a platinum-iridium cylinder stored in France. However, as of May 20, 2019, the kilogram is defined based on fundamental physical constants, specifically the Planck constant, allowing for a more stable and universally reproducible standard.

In practical applications, secondary mass standards are used. These are precisely manufactured objects, often made of stainless steel or other stable materials, whose mass is known with high accuracy relative to the primary standard. They come in various classes of accuracy, such as E1, E2, F1, F2, M1, M2, and M3, with E1 being the highest accuracy class and M3 the lowest. These classes are defined by international standards like the International Organization of Legal Metrology (OIML) recommendations.

Mass standards are crucial for metrology, the science of measurement. They enable the calibration of weighing instruments used in laboratories, industry, commerce, and scientific research. Without reliable mass standards, consistent and comparable measurements of mass would be impossible. Their maintenance and calibration are strictly controlled to ensure the integrity of mass measurements worldwide.