Pore size is commonly expressed as `pore diameter'. The pore diameter is calculated from the applied gas pressure, which causes the liquid-filled pores to be emptied, resulting in a flow of gas through the sample.
BS 7591-4 is an international standard that discusses the test methods for porosity and pore size distribution of materials.
BS 7591-4 describes the evaluation of pore size characteristics (such as mean, maximum, and the distribution of pore sizes) that allow the flow of liquid from one side of the wetted structure to the other. It is a comparative and usually non-destructive test.
BS 7591-4 specifies a method, that is suitable for the study of through-pore materials, such as filter paper, paper, polymer membrane filters, and cloth.
The method described in BS 7591-4 enables pore sizes to be estimated within the general size range of about 50 mm down to about 0.05 mm. The test involves the application of pressures up to 1 MPa2) (150 psi). For most materials, this pressure does not cause compaction or deformation of the material which results in a change in the pore structure.
Note 1: The technique specified in BS 7591-4 is comparative, as for most porous media a theory is not available to allow an absolute calculation of pore size.
Note 2: It is the recommended method for the evaluation of filter papers (see BS 6410).
BS 7591-4 on porosity and pore size distribution of materials is relevant to:
Porosity is a term that is often used to indicate the porous nature of solid material and is more precisely defined as the ratio of the volume of accessible pores and voids to the total volume occupied by a given amount of the solid.
BS 7591-4 has been prepared under the direction of the general mechanical engineering standards policy committee and is one of the series which describes recommended methods for the evaluation of porosity and pore size distribution.
BS 7591-4 describes the evaluation of porosity by liquid expulsion, this helps users to study different types of pores, that can be pictured as either aperture, channels, or cavities within a solid body or as the space (i.e., interstices or voids) between solid particles in a bed, compact or aggregate.
BS 7591-4 presents the users with the information which is necessary to study the pore shape and interconnectivity and to determine the internal and external surface area, for some purposes.
Overall, BS 7591-4 is useful as it provides guidance on the method of evaluation by liquid expulsion for porosity and pore size distribution of materials that can be beneficial for your business and can also help you to expand your business globally.