Gas pycnometer: precise measurement of the density of solid and porous materials
Determine the true density of your materials using the gas pycnometer
A gas pycnometer is a density measurement technique that uses an inert gas, usually helium or nitrogen, to analyze solid, porous, or powdered materials. It allows the determination of the true density of a sample by taking into account the volume occupied by the material, excluding open and interstitial pores.
Recognized for its accuracy and reproducibility, this method is commonly used in the pharmaceutical, food, materials, polymer and ceramics industries, where the characterization of the physical properties of materials is essential.
How does the gas pycnometer work?
The gas pycnometer is based on the principle of gas expansion within a measuring cell. The process unfolds in several stages:
- Sample introduction – The solid or powdered sample is placed in a hermetically sealed measuring chamber.
- Reference gas injection – An inert gas is introduced into an adjacent chamber of known volume.
- Pressure balancing – A valve opens to allow the gas to be distributed between the reference chamber and the one containing the sample.
- Pressure variation measurement – The final pressure is recorded, and using the ideal gas law, the actual volume of the sample is calculated.
- Calculating density – Given the mass of the sample, the actual density is determined by the relationship density = mass/volume.
This method allows the density of solids to be measured without being influenced by the open porosity of the material, which differentiates it from classical methods of measuring apparent density.
Technical characteristics of the gas pycnometer
The gas pycnometer offers unparalleled accuracy for determining the true density of solids and powders. Its main features are:
- Type of gas used : helium (most common due to its small molecular size) or nitrogen.
- Measurement accuracy : generally less than 0.01% relative error.
- Analysis chamber volume : suitable for samples of varying sizes (from a few mm³ to several cm³).
- Analysis time : fast, with measurements taken in a few minutes.
- Material compatibility : applicable to non-volatile materials and chemically stable in the measurement atmosphere.
- Applicable standards : ASTM D2856, ISO 12154, and other material characterization standards.
Thanks to these performance features, the gas pycnometer is an essential tool for quality control and research analyses.
For which matrices is the gas pycnometer suitable?
The gas pycnometer is designed for the analysis of various solid matrices, whether dense, porous, or powdered:
Main industrial applications of the gas pycnometer
The gas pycnometer is used in many industrial sectors to characterize the physical properties of materials:
Léa Géréec
Technical and scientific advisor
