CHARACTERIZATION OF A PRIMARY STANDARD CONTROLLED CLEARANCE PRESSURE BALANCE USING HEYDEMANN AND WELCH MODEL

摘要

For a traceable measurement to be verified and meaningful, it is important that all the measuring apparatus have to be calibrated against standards that are traceable to National/International Standards. Calibration is a process that determines the operational integrity of mislaying instruments by determining their measurement uncertainties. In order to ensure the calibration of a measuring instrument traceable to National Standards, a hierarchy of standards and standards laboratories are established. A primary pressure standard that can metrologically characterized in a complete and an independent way with reference only to the basic units of the S.I. system, is defined as force per unit area (pressure balance) or the height of a liquid column (liquid manometer). Pressure balances are excellent primary standards for measuring pressure with high resolution and high accuracy. Characterization of primary standard pressure balance (controlled clearance) will be presented in this work.