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Gas Displacement Pycnometry System

Gas pycnometry is recognized as one of the most reliable techniques for obtaining true, absolute, skeletal, and apparent volume and density. This technique is non-destructive as it uses the gas displacement method to measure volume. Inert gases, such as helium or nitrogen, are used as the displacement medium. Density calculations using the gas displacement method are much more accurate and reproducible than three minutes without sacrificing accuracy.

After analyses are started with a few keystrokes, data are collected, calculations are performed, and results displayed. A minimal amount of operator intervention is required.

Non-destructive Icon
Maintain product integrity with this non-destructive test
Programmable Icon
Eliminate error with programmable automatic repeat and data acquisition set to your tolerances to comply with your SOPs
Variety of Gases Icon
Ability to use a variety of gases
Size range Icon
Maximize your investment-Adaptive configuration to meet your sample size needs
Low cost Maintenance Icon
Low-cost, minimal maintenance, and small footprint
Barcode Compatibility Icon
Increase efficiency and compliance with barcoding compatibility
Stopwatch Icon
Speed of analysis, accuracy, repeatability, and reproducibility
Keypad Icon
Versatility of keypad or Windows software operation
Mass Balance Icon
Eliminate procedural steps with direct input from an analytical balance

This technique uses the gas displacement method to measure volume accurately. Inert gases, such as helium or nitrogen, are used as the displacement medium. The sample is sealed in the instrument compartment of known volume,the appropriate inert gas is admitted, and then expanded into another precision internal volume. The pressures observed upon filling

the sample chamber and then discharging it into a second empty chamber allow computation of the sample solid phase volume. Helium molecules rapidly fill pores as small as one angstrom in diameter; only the solid phase of the sample displaces the gas. Dividing this volume into the sample weight gives the gas displacement density.


On an elementary level, the volume of a solid material can be calculated by measuring its length, width, and thickness. However, many materials have within their structure surface irregularities, small fractures, fissures, and pores. Some of these voids or pores are open to the

surface or closed within the structure of the solid material. Therefore, differences in the material volume depend on the measurement technique, measurement method, and the conditions under which the measurements were performed.

Density Type Definition Material Volume Open-PoreVolume Closed-PoreVolume Inter particle Volume External Void Volume Addressed by
True (Absolute) The mass of a substance divided by its volume, excluding open and closed (or blind) pores AccuPyc II
Skeletal(Apparent) The ratio of the mass of the solid material to the sum of the volume including closed (or blind) pores

AccuPyc II
Envelope The ratio of the mass of a substance to the envelope volume (imaginary boundary surrounding the particle)
Bulk Mass of the material divided by the volume occupied that includes interstitial space GeoPyc
TAP Apparent powder density obtained under stated conditions of tapping GeoPyc with T.A.P. function