Compression Liquid Extrusion Porosimeter

PMI Compression Liquid Extrusion Porosimeter

A very versatile instrument that I’ve been looking at recently is the Compression Liquid Extrusion Porosimeter from PMI. This clever piece of equipment will measure pore volume like a mercury intrusion porosimeter, although without the use of mercury or any other toxic substance, and will also measure liquid permeability like a permeameter. What’s more, it can do so while holding the sample under compressive stress.

A quick recap on the three main types of instrument covered by the pore size website might be useful here. Many of the previous articles have concerned porometers. A porometer’s main function is to measure pore diameters, although it can also be used for other aspects of pore size and for determination of gas permeability. Its principle involves use of a wetting liquid which fills the pores and is then pushed out by forcing a gas through the sample under gradually increasing pressure.

A porosimeter focuses instead on pore volume. In this technique, liquid is forced into or, in the case of an extrusion porosimeter, out of the pores. Measurement of the pressure required to do so allows calculation of pore data.

A permeameter can be used to measure a material’s permeability to liquid, gas or vapour, based on a calculation which includes the pressure drop observed across the sample.

When it comes to porosimeters, many people will be familiar with the mercury intrusion type. A major drawback of these instruments, as their name suggests, is that they rely on mercury – a substance that biotech, pharmaceutical, food and environmentally focused industries avoid.

PMI’s Compression Liquid Extrusion Porosimeter is a welcome option in those fields, as it has no potential for harming staff, contaminating products or polluting the environment. Furthermore, it avoids the effort and expense of handling and disposing of toxic materials.

During characterisation of a variety of porous materials it automatically applies compressive stress to the sample, allowing the user to choose any level up to 1,000 psi. In fact, the whole process is highly automated and requires only minimal effort from the operator. The pore structure can be determined in relation to varying compressive stress without having to dismantle the sample chamber.

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