PMI Liquid Permeameter

PMI Liquid Permeameter

The principles, features, functions and applications of an instrument become clearer when a specific model is examined in detail. Today we will look specifically at a liquid permeameter. This one is from a range of PMI permeameters which Meritics is very happy to recommend.

The purpose of the instrument, of course, is to measure the permeability of a material – in other words, its ability to allow the flow of a fluid through it. In the case of this permeameter, the fluid is a liquid, but others can be used for similar measurements in relation to gas or vapour.

Permeability is measured in terms of the fluid’s flow rate, which in turn is calculated by determining the pressure drop across a sample of the material and using a formula that also takes into account the sample’s thickness and the fluid’s viscosity. In practice, the measurement of flow rate is made by looking at the distance a column of water drops in relation to time and pressure. Key advantages of the method include the speed with which it can be applied – in this case about ten minutes per test – as well as the accuracy and reproducibility of its results.

Using the PMI liquid permeameter, a wide variety of samples, in terms of shape and size, can be tested non-destructively. Materials investigated in this way have included paper, battery separators, membranes and filter media, as well as vegetables, meat and other food products. The permeameter can be equipped with multiple sample chambers to suit a variety of needs.

Hydrophobic materials, which have been a problem in the past, can now be tested by increasing the pressure to anything up to 200 psi, and thereby forcing the liquid through the sample. Testing can be carried out under ambient temperatures, or the temperature can be raised to recreate the conditions in which the material will actually operate.

Other user-friendly features of the PMI permeameter include its Windows-based software, compatible with Windows 95 and higher, which provides control, measurement, collection of data and generation of reports. If preferred, however, the system can be transferred to complete manual control. During operation, a real-time graphical test display gives continuous information on the test status and results.