Determination of density by gas pycnometry
The density of a substance is its mass per unit volume. Mass can be easily determined with a scale. However, the determination of volume is more challenging, usually due to solids being irregularly shaped, porous, powdered or granular. Volume, and thus density, may be defined differently if pores are included (raw density) or excluded (true density) into the solid samples volume. The density is based on the solid samples volume excluding the pore volume of porous solids.
Measuring method
Definition of different volume terms
With a pycnometer (Greek, „gauged vessel”) the amount of a certain medium (liquid or Helium or other analytical gases) displaced by a solid can be determined. Examples for the use of density determinations for finely ground or bulky solids include, but are not limited to, for example the differentiation between solids, quality insurance, determination of open and closed pore volume in foams and determination of so-called vacuolar volume in the quality control of milk powders. These fields illustrate the versatility of gas pycnometry and exceed the limits of liquid pycnometry. The main advantages of the gas pycnometry are:
- Fast
- Precise
- Requires no organic liquids
- Low user expense
- Automatization
Schematic measurement setup
Analyzer
- Single station automatic gas pycnometer for volume and density measurement of porous solids and powders
- Sample volume of 3P densi 100 ranges from 1 cm³ up to 100 cm³
- Easy to handle the instrument by the 10-inch touch-screen