Unconventional Shale Gas Consortium

Permeation and Diffusivity Measurement

The FluiDIFF instrument uses a Magnetic Suspension Balance to measure the temperature dependent permeability and diffusivity. The tube is filled with a substance, connected to the balance, and the loss in mass is measured continuously. Only Magnetic Suspension Balance instruments can provide the required long term stability and accuracy to gain exact results for permeability and/or diffusivity. This is realized by the unique automatic base line drift correction and possibility of balance calibration during the measurement. The accurately measured mass loss can be converted into temperature dependent permeability or diffusivity rates. This measuring method is being used at several standard-institutes around the world for generating reference gas mixtures which are linked to the national primary standard. These traceable mixtures are definitely needed to calibrate modern gas analysers and sensors. The permeability and diffusivity measurement with Rubotherm’s Magnetic Suspension Balance FluiDIFF offers the possibility of calibrating the permeation and Stefan tubes themselves with utmost precision.

Specifications / Capabilities:
  • Contact free weighing of all kinds of samples in hermetically closed reactors with patented magnetic suspension.
  • Hermetic separation of measurement area (sample) and weighing area (balance) to avoid any damage, destruction or interference from the process media (e.g. corrosive gases, vapours), pressure or temperature.
  • The reactor of the magnetic suspension balance is completely metal sealed, even highly aggressive or corrosive atmospheres can be used for measurements over a wide pressure and temperature range.
  • Excellent long term stability. The sample can be automatically disconnected from the balance at any time to re-tare and/or calibrate the balance. After that it is reconnected and lifted up to measuring position to continue the measurement. High precision long term measurements without baseline drift are performable without limit in measuring time.
  • The density of the measuring atmosphere in the reactor is determined highly accurate by applying Archimedes’ principle. A sinker is weighed by the balance additionally and simultaneously to the sample, so determining the buoyancy effect acting on it.
  • Modular construction: The magnetic suspension balance can flexibly be adapted to all kinds of applications by combining different modular parts of the instrument.
  • No other instrument than Rubotherm’s patented magnetic suspension balance is able to work with high pressure and high temperature at the same time and additionally handle aggressive media (e.g. H2 at high pressure and/or temperature) and vapours.

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