Density measurement of liquids

What is density?

The density of a sample is its mass per unit volume. It is often expressed in g/cm³ or kg/m³. Densities are used in many sectors of activity, in particular for the dimensioning of processes, the modeling and the characterization of compounds.

How to measure density?

Depending on the need, this physical quantity can be measured more or less precisely. The desired precision implies the use of more or less complex methods and techniques to implement.

A simple way to measure the density of a liquid is pycnometry. A pycnometer is a volume instrument calibrated as a function of temperature. The instrument thermostated or left at room temperature is filled with the fluid up to the gauge mark. It is then weighed using a precision scale. This technique makes it possible to measure densities with an accuracy better than 0.001 g/cm³. At Calnesis, this type of measurement is accessible between -20 and 350°C.

The principle of the vibrating tube density meter is to vibrate a U-shaped tube containing the fluid. The tube vibration frequency is directly related to the density of the fluid according to an equation that requires calibration using two known fluids.

For greater accuracy, or if the measurement must be made under pressure, a vibrating tube density meter can be used. This technique allows measurements up to 200°C and 400 bars, with an accuracy of around 0.00001 g/cm³! It is the ideal solution for research and optimization of thermodynamic models.

For “hot” measurements of molten polymers, the simplest method to determine their density is to use an MFI plastometer. This apparatus in fact makes it possible to heat the polymer compound in order to melt it, and to extract known volumes therefrom by extrusion. The density is then determined by weighing an extruded volume of molten polymer.

Deliverables

The results provided during these measurements are tables of density and/or density values ​​according to your fluids, temperature and pressure if applicable.

Why choose Calnesis to measure the densities or densities of your products?

• The wide temperature and pressure ranges covered by our devices are suitable for the majority of applications (-20 to 350°C, 1 to 400 bar)
• We offer you the precision/cost ratio adapted to your needs
• Our proven protocols ensure reliable results (accuracy up to 10-5 g/cm³)
• Our facilities allow measurements to be taken on corrosive, toxic compounds, solids at room temperature, dissolved gases, etc.

Examples of results obtained

Data extracted from work carried out in collaboration with BRGM and LaTEP (see dedicated article via the link below):

Experimental Data and Modeling of Solution Density and Heat Capacity in the Na–K–Ca–Mg–Cl–H2O System up to 353.15 K and 5 mol·kg–1 Ionic Strength
J. Chem. Eng. Data
DOI: 10.1021/acs.jced.7b00553