Primary mercury columns using floats - exchange of experiences

Project Description

Interferometric mercury U-tube manometers with laser beam reflecting floats belong to the most accurate primary standards in the pressure range between 100 Pa and 100 kPa. Being fundamental instruments, they might be used as an independent method for the realization of the pressure scale. A very important issue for the performance of the mercury manometers, particularly at low pressures, is the repeatability of the pressure measurement which significantly depends on the floats behaviour affected by the mercury surface vibrations and mercury capillary effects on the U-tube walls and the float surfaces. This demands sophisticated floats. The project partners will share their knowledge and experience in existing float constructions in order to understand more deeply the technological obstacles and the underlying physics. The project will promote development of better floats, and, thus, will lead to a reduction of the mercury manometer measurement uncertainty, especially for low pressures.

Final Report 2014-01-27

In the end ist not going to be possible that CEM uses CENAM´s floats, so no further activities can be performed.

Progress Report 2013-03-25

In order to start the exchange of experiences a survey organised by CEM has been performed in order to know the main difficulties and differences among the systems. It seems the mercury columns belonging to CENAM and CEM are the most similar ones. It has been planned that CEM will make measurement using CENAM's floats in July. Further exchange of experiences with PTB will go on as well.