Pycnometry: precise measurement of density and specific gravity
Determine the density using a pycnometer
The pycnometer is a laboratory instrument used to measure density with high precision. Employed in various industrial sectors, it allows for quality control of raw materials, formulations, and finished products by ensuring reliable and repeatable measurements.
Thanks to its simple and effective operating principle, the pycnometer is an essential solution for laboratories and manufacturers seeking to characterize the density of their samples at a given temperature.
What are the different types of pycnometers?
glass pycnometer
- The most common
- Suitable for solid and liquid products
Metallic pycnometer
- Suitable for solid and pasty products
Gas pycnometer
- Suitable for solid and porous products
How does a glass pycnometer work?
The pycnometer is based on the principle of comparative weighing between an empty container and one filled with a product of unknown density. Its operation follows several steps:
- Weighing the empty pycnometer – The instrument is first accurately weighed using an analytical balance.
- Filling with the liquid to be analyzed – The pycnometer is filled up to a defined mark, ensuring a constant volume.
- Air bubble removal – To ensure an accurate measurement, any presence of air in the liquid is removed by agitation or degassing.
- Weighing the filled pycnometer – The total weight is measured to determine the mass of the liquid contained.
- Calculating density – Density is obtained by dividing the mass of the liquid by the known volume of the pycnometer.
The accuracy of the pycnometer for liquids depends on the volume of the instrument, the accuracy of the balance used, and the temperature control, which influences the density of the liquids.
Technical characteristics of the glass pycnometer?
The pycnometer is designed to offer high accuracy in measuring fluid density. Its main technical features include:
- Manufacturing materials : borosilicate glass, stainless steel or chemical-resistant polymers.
- Volumetric capacity : from a few milliliters to several hundred milliliters depending on analytical needs.
- Measurement accuracy : depends on the volume and the balance used, with an uncertainty often less than 0.001 g/cm³.
- Compliance with standards : pycnometers used in industry comply with standards such as ISO 2811 for paints or ASTM D70 for bitumens.
- Types of stoppers : capillary stopper to control the exact volume of the liquid and limit evaporation.
The choice of pycnometer depends on the type of liquid to be analyzed and the specific requirements for accuracy and chemical compatibility.
Main industrial applications of pycnometers
The pycnometer for liquids is used in many sectors for quality control and research & development:
Léa Géréec
Technical and scientific advisor
