From Particle Formation...

... To Particle Characterisation

Density is defined as mass per unit volume.

**Analysis of sample mass** can be simply and accurately performed using a balance, but analysis of sample volume, particularly of powders or irregularly shaped materials can be difficult and can be perceived and measured in more than one way:

**as bulk volume with corresponding bulk density**- includes volume of solid phase, plus volume of inter-particular space and pores within particles**as apparent/envelope/geometric volume giving apparent/envelope density**- includes volume of solid phase plus pores within the particle**as true/skeletal volume for true density measurement**- includes volume of solid phase only and any closed pores within that are not open to the outside surface

Corresponding measuring methods are:

**Bulk Density**- volume determined by the use of graduated cylinder, the cylinder can be tapped giving a measure of the so called Tapped Density**Apparent/envelope Density**- volume of large geometric shapes easy to measure (ruler, calipers), volume of irregular shapes measured by powder pycnometry using a free flowing powder, volume of small, irregular shapes measured by mercury displacement**True Density**- For regular shapes this is easy to measure using an accurate balance and a ruler, for irregular or fractured shapes we employ the Archimedean principle of fluid/gas displacement to measure the volume. The gas pycnometry operating principle is Gas Law: PV = nRT Where P is the gas pressure, V is the volume containing the gas, n is the number of moles of the gas, R is the universal gas constant and T is the temperature of the gas. Introducing a sample into an analysis chamber of a known volume we determine the volume of a gas displaced by the sample and true volume of the analysed material. Most commonly used gas is helium but other gasses are also possible.

**Applications**

Common applications: cement, pharmaceutical powders, catalysts, dairy powder, ceramics, metallic powders, nanocomposites

**True Density measurement**is one of the simplest and most economical methods of Quality Control, the measurement takes few minutes and can be highly automated.**Pycnometric or True Density analysis**combined with Mercury porosimetry can provide a measure of materialsâ€™ porosity.**Gas Pycnometry**can be used to determine percentage of solids in the slurry**Specialist applications**allow the determination of open and closed cell porosity of rigid and semi rigid foams.

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Pentapyc 5200e

Ultrapyc 1200e / micro-Ultrapyc 1200e

Ultrafoam 1200e & Pentafoam 5200e

Multipycnometer

Stereopycnometer

Autotap / Dual Autotap