Realization of the pascal from the boltzmann constant using mass comparison of artifacts in vacuum and gas

A method of realizing a low-uncertainty property, comprising:

• measuring absolute masses of respective buoyancy artifacts under a vacuum condition, wherein the buoyancy artifacts have substantially the same nominal mass, substantially the same surface area, and different volumes defining a volume difference;
• determining an absolute mass difference between the buoyancy artifacts based on the absolute masses;
• measuring effective masses of the respective buoyancy artifacts under a gas pressure condition;
• determining an effective mass difference between the buoyancy artifacts based on the effective masses;
• measuring or determining two variables selected from a pressure of the system, a temperature of the system, and the molecule weight of the gas;
• and
• determining the low-uncertainty variable selected from the pressure, the temperature of the system, and the molecule weight of the gas, based on the absolute mass difference, the effective mass difference, the Boltzmann constant, the volume difference, and the two determined variables, using at least one gas law equation.

A pressure realization system for realization of the Pascal, comprising:

• at least a pair of buoyancy artifacts having substantially the same nominal mass, substantially the same surface area, and different volumes defining a volume difference;
• a vacuum mass comparator that includes a chamber, a pump coupled to the chamber to provide vacuum conditions, and a mass balance capable of comparing at least the two buoyancy artifacts within the chamber;
• a gas supply system coupled to the chamber for supplying a gas into the chamber to provide gas pressure conditions;
• a processor that is operatively coupled to the vacuum mass comparator in order to receive data therefrom, the processor being configured to generate a pressure reference value based on:
• an absolute mass difference between the buoyancy artifacts measured by the vacuum mass comparator,
• an effective mass difference between the buoyancy artifacts measured by the vacuum mass comparator under the gas pressure conditions,
• the Boltzmann constant,
• the volume difference,
• the molecular weight of the gas at the pressure condition, and
• the real gas coefficients of the gas;
• and
• the temperature at the pressure condition.