Calibration of hydrometers at NPL

89-92Hydrometry is a simple approach to measure density of a liquid using laws of flotation. Reference (Standard). hydrometers which are used to calibrate normal hydrometers by comparison process are calibrated by hydrostatic weighing method. Optimum accuracy may be achieved by hydrometers only if all relevant corrections are incorporated in the calibration process. This paper highlights the salient features of hydrometry.