Porometer, Permeameter or Porosimeter?

Depending on your application, characterisation of the porous nature of a material may require more than one instrument and method.

Our Pore Size blog covers three main types of equipment: porometers, permeameters and mercury porosimeters. A quick recap may be of help here.

A porometer is essentially used to measure pore size in terms of diameter. It will determine mean, maximum and minimum diameters, as well as pore size distribution. It can also be used to calculate gas permeability. The technique involves filling the material’s pores with a wetting liquid, then removing the liquid by passing a non-reacting gas through the sample under slowly increasing pressure. Pore data can be computed from the differential pressures and flow rates recorded.

A permeameter measures the permeability of a material to liquid, gas or vapour – in other words, its ability to allow fluids to flow through it. This is calculated by recording the pressure drop across the sample and applying a formula that also takes into account the sample’s thickness and the fluid’s viscosity.

A porosimeter measures pore volume – and distribution of pore volume – using a method based on determining the pressure required to force liquid into (intrusion) or out of (extrusion) the pores. Within the context of this blog site, the most relevant of these instruments are the mercury intrusion porosimeters.

It should be noted that although mercury porosimetry can provide pore data very quickly and simply, it is not a suitable method for all applications. In cement-based materials, for example, calculation of pore size distribution is difficult because the mercury tends not to enter pores at low pressure but fills both large and small pores simultaneously once a particular threshold has been reached.

Another limitation is that this technique measures the largest entrance into a pore but gives no information on the pore’s internal size.

If you are unsure, Meritics will be happy to advise on the most appropriate instruments and techniques in all cases.

Leave a Reply