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Measuring Instruments
Nano-Perm Porometer


  • Ceramic/high molecular gas separation membranes
  • Hollow fiber dialysis membranes
  • Ceramic/high molecular water treatment. membranes
  • Ceramic PV membranes


  • Nano pore-diameter distribution
  • Permeability of various non-condensable gases
  • Permeability and separation factor of water vapor and hexane vapor

Key features

  • Enables non-destructive tests without the use of mercury and liquid nitrogen
  • Short-time measurement
  • Enables hysteresis measurements (Dry→Wet→Dry / Wet→Dry→ Wet)
  • Enables the measurement of both hydrophobic and hydrophilic samples
  • Computer-controlled automatic measurement


  • Pore size measurement range: 0.5〜50 nm
  • Gas permeability measurement range: 10-10〜10-6mol/sec/m2/pa
  • Maximum sample size: (cylinder-type) φ45x100mm
    (membrare-type) φ70x20mm


If water vapor is condensed in pore spaces as described by the Kelvin equation for capillary condensation, all pores smaller than the Kelvin radius are filled by condensed water in relation to the relative air humidity, resulting in a decrease in the air permeability.

The pore size distribution of porous membranes can be estimated based on the decrease in the air permeability rate, and the pore size can be calculated among the Kelvin equation for capillary condensation. In this process, it is assumed that the pore size distribution peaks when the decrease in the permeability reaches a maximum.

The principle of the Nano-Perm Porometer is to measure the size of the pores that are closed as a function of the air humidity based on the permeability of non-condensable nitrogen gas. The Kelvin equation for capillary condensation is shown below.

 - Kelvin equation
v: Molar volume of gas θ: Contact angle σ: Surface tension

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