FORCE Technology has the Danish national reference laboratory for volume and density. The laboratory offers accredited calibration of density meters for gas and accredited determinations of liquid density with the traceability to mass and distilled water.

The laboratory has a series of reference as Weights and balances, pycnometers, density meter and other reference equipment. Measuring the density is particularly interesting in the area of gas, due to the natural gas sector and in the area of liquid in connection with the performance of e-marking. But also in other types of industries, the density measurement is important, and the tasks are typically calibration of their density meters or determination of the density of a special liquid.

The Natural gas density is determined in the North Sea and in most of the transmission grid.
The need for accuracy for the calibration of these meters is typically in the range 0.1% – 0.2%.
In food industry the density is important because it is often used for conversion between volume and mass for e-marking of pre-packaged goods. Also in the oil industry is it used for conversion between volume and mass flow. The need for accuracy ranges from 0.01% – 1%.

The density of gas is determined directly by weighing a container whose volume is determined gravimetric with distilled air-free water, where the density of water is known. Traceability goes to mass and internationally accepted formulas for water and air density.

The density of the gas can also be found by calculation the state equation for gas by measuring the gas temperature T and pressure p, and a knowledge of the gas Compression factor Z and mole mass M. The gas Compression factor is determined with a so-called Z-meter where the gas is brought to expand between two weighted volumes. From the gas state equation the mole mass can then be determined. The total traceability goes to mass, pressure, temperature and internationally accepted formulations for water and air density. Liquid density can be determined directly through the resort and filling of a container whose internal volume is known and predetermined by way of air-free distilled water.

The density of a liquid is determined directly by filling and weighing a container whose volume is determined gravimetric with distilled air-free water. The density of air-free distilled water is determined by internationally accepted tables and formulars. Measurement of liquid density is normally performed either with pycnometer or with an electronic density meter using the vibration of a U-shaped tube, as the resonant frequency is dependent on the density.


Rune Christensen

FORCE Technology
Park Allé 345
DK 2605 Brøndby
Phone: +45 43 25 07 52