Be warned, this is a very large area in which there are many choices to be made in terms of equipment offered by a range of manufacturers. Each product has qualities and design features which need to be studied carefully, in relation to the particular application’
Meritics aims to inform those decisions by presenting the key facts, along with news, background information and – above all – good advice, to identify the perfect solution for each user.
The starting point in many porometry techniques is to measure the flow rate of an inert gas, as it is passed through a dry sample of the material, under increasing differential pressure. When the same sample is brought into contact with a wetting liquid, its pores spontaneously fill.
Now the flow of liquid through the wet sample is determined with increasing differential pressure. Pore structure characteristics can then be computed from the differential pressures and flow rates measured.
As well as exploring the bewildering variety of porometers, www.poresize.co.uk also covers the related topic of permeameters. In this case what is being measured is the ability of a porous material to allow the flow of liquid. Calculation of this flow rate, or permeability, involves measurement of the pressure drop across the sample, the thickness of the sample and the viscosity of the fluid.
Among many variations to be explained on www.poresize.co.uk is mercury porosimetry. Here the sample is immersed in mercury, which is forced into its pores under pressure. The pressure required is inversely proportional to the size of the pores. Although this can be a very quick, easy and useful analytical tool, it is not applicable to every situation – so advice from Meritics on its application is highly valuable. A brief survey of today’s porometers and their key applications shows their tremendous versatility and variety.
They can assess pore structures both in the thickness direction (z) and the in-plane direction (x and y). They can deal with samples of all shapes and sizes – without necessarily requiring a piece to be cut from the material under test. Porometers can also be used in assessing the effects on pore structure of compressive stress, cyclic compressive stress, temperature and the chemical environment.
Similar variety is found in permeameters. Gas and liquid permeameters assess permeability of gases or liquids, respectively, through porous materials. Microflow and diffusion permeameters are for measurement of gas or vapour permeability through materials at very low levels. Vapour transmission analysers can be used to determine flow rate of vapour transmitted in response to a humidity gradient.
Furthermore, standard porometers and permeameters can be adapted with optional features to meet many more specialised needs. Meritics is there to support people through the complex decision-making process, with resources including a telephone helpline and field-based engineers. Importantly, because Meritics represents a whole range of leading instrumentation manufacturers, it has no vested interest in pushing customers towards any particular product – so its advice is impartial as well as expert.
For further information on pore size visit http://www.poresize.co.uk
To find out more about products and services available from Meritics, go to http://www.meritics.com