Porous Materials Inc Products - Pycnometers

Automated Gas Pycnometer

PMI's Automated Gas/Helium Pycnometer is used to determine the true volume and true density of powders and bulk solids using high-precision volume measurements and density calculations. The true volume of a solid is calculated from the measured drop in pressure when a known amount of gas is allowed to expand into a chamber containing sample. Thus, the true volume obtained by pycnometry includes any pore volume accessible to the gas. Helium is the preferred gas, because it exhibits ideal gas behavior. However, almost any non-corrosive gas including air can be used. The true density is obtained by dividing the weight of the sample by true volume.

  • Nondestructive measurement
  • Test substance
  • Automated control
  • Stainless steel embodiment
  • Temperature control (optional)
  • Option to purge by a suitable method
  • Highly reproducible & accurate results
  • Low required pressures
  • Capable to be programmed for automatic repeat measurements or for data acquisition
  • Windows based graphic user interface (GUI)
  • Automatic pressure and volume calibration routines
  • Under user selected tolerances.
  • Graphic presentation of the data to be evaluated and analysis results
  • Exporting graphic files to window based word / excel processing files for report generation
  • Provision for off-line data processing.
  • Integrated detailed help system.
  • True density is provided by the software.
  • Pycnometer isuse“ Gas replacement method”- Applying the principle of Archimedes -- Gas expansion replacement method,Using small molecules of inert gas ( Helium or nitrogen ) Bohr's law under certain conditions(PV=nRT),The true volume of the measured sample is calculated by measuring the decrease in the gas volume of the test chamber caused by the sample being placed in the test chamber, and then the true density is analyzed. 

True density = mass / true volume

  • Test method: Collect the pressure P1 and volume V1 of the reference cavity and record; put the sample of unknown volume V into the test cavity of known volume V2, inject gas into the test cavity and record the stabilized pressure P2; connect the test cavity with the reference The stabilized pressure P3 is recorded after the cavity, and the volume V of the sample to be tested can be calculated according to the pressure value after the equilibrium stabilization and the known volumes V1 and V2, and the true density of the sample is calculated from the quality and volume of the sample.

P = Vv / [Vv +Vs]

P = Porosity

Vv = Pore Volume

Vs = Sample volume

Test type Vacuum type, High pressure type and Ambient pressure type
Sample Chamber S.S.316 Stainless Steel material
Chamber volume

Standard 30 ml (diameter 5CMx deep 3CM) or 100 ml, and other large volume sample tanks (such as 300ml)

Sample Geometries Flat sheet, hollow fiber, granule, block, etc.
Sample volume detection accuracy 0.02%
Specimen specific gravity range 6.0g/cc〜0.1g/cc
Operation Autotest and Manual control
Software The range of precision to be achieved and the number of measurements can be set directly on the software.

✓ Test Results:

✓ Comparison between liquid gravimetric method and gas true density method: