Height difference measurement in PTB’s liquid column manometer

Sven Ehlers

Abstract

A primary liquid column manometer (LCM) is under development at PTB for use in conducting low-pressure measurements up to 2 kPa in gauge and absolute pressure. To calculate pressure, all measured input quantities of the instrument, as there are liquid density, gravitational acceleration, and length, are traceable to the International System of Units (SI), thus making the LCM a primary pressure standard. The LCM is well suited to identifying small force-induced errors, particularly those of force-compensated pressure balances with non-rotating piston in their lower measurement range, and as such to disseminating the pascal, the SI unit of pressure.<BR/>This report focuses on the measurement of the height difference inside the instrument, where homodyne plane mirror interferometry is applied using the liquid’s free surface as the reflecting mirror for the laser beam.

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IMEKO-TC16-2023-12.pdf

DOI

10.21014/tc16-2023.12

IMEKO TC

TC16 - Pressure and Vacuum Measurement

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