PMI Products

Product Category

Based on Porosity Characteristics

The Products

Porometers

What are PMI Porometers?

A Porometer is capable of measuring the diameter of a pore at its most constricted part, the largest pore diameter, the mean pore diameter, the pore distribution, and gas permeability in a porous material. The pores in the sample are spontaneously filled with a wetting liquid. Pressure of a nonreacting gas on one side of the sample is slowly increased to remove liquid from pores and permit gas flow through the pores. Measured differential pressures and flow rates of gas through wet and dry conditions of the sample are used to compute pore structure characteristics. Sophisticated design and instrumentation leads to high accuracy and reproducibility of results.

Products in the porometer line are designed to perform a variety of tasks. The pore structures in the thickness direction (z-direction) and in the in-plane directions (x & y) can be determined. Many sample shapes and sizes can be accommodated. Tests can be performed without cutting any sample from the product. Effects of compressive stress, cyclic compressive stress, temperature and chemical environment on pore structure can be determined. Some of the additional features that can be added to a porometer are multiple sample chambers, generation of fast and reproducible data, multiple test options, liquid permeability, and predefined product selection criteria.

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Permeameters

What are PMI Permeameters?

A permeameter is an instrument that is capable of measuring the ability of a porous medium to permit flow of a fluid. Flow rate of a fluid through a porous medium is determined by the pressure drop across the sample (Dp), the thickness of the sample (l), and the viscosity of the fluid (m). The flow rate, F, at average pressure (average of inlet and outlet pressure) is given by:

F = k (A/m) (Dp/l)

in this relation is known as permeability of the porous medium for the fluid. Permeameters accurately measure flow rates of fluid and pressure drop across the sample and values of area, thickness, and viscosity are entered in the system. The instrument returns the ability of the porous material to permit fluid flow either in terms of permeability, k, or simply in flow rate per unit pressure gradient per unit area, or in terms of other commercial units like Frazier, Gurley, and Rayl.

Products in the permeameter line are designed to perform a variety of tasks. The gas permeameters determine permeability of gases through porous materials. Liquid permeability is determined by liquid permeameters. Microflow and diffusion permeameters determine very small gas or vapor permeability of materials. The vapor transmission rate due to humidity gradient is determined by vapor transmission analyzers. Other unique features that a permeameter may have include multiple sample chambers, sample testing without cutting, chambers for unusual sample shapes and sizes, permeability of strong chemicals, elevated temperature permeability, high-pressure permeability, and in-plane permeability.

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Porosimeters

What are PMI Porosimeters?

Porosimeters are instruments that are capable of measuring pore volume and pore volume distribution. These instruments are based on the principle of either liquid intrusion into pores or liquid extrusion from pores.

Mercury cannot flow spontaneously into pores of many porous materials, but application of pressure on mercury can force it into pores. The pressure required to force mercury into pores gives the pore diameter and the volume of intruded liquid gives pore volume and pore volume distribution. Mercury Intrusion Porosimeters are based on this principle and are capable of operating under a wide range of pressures.

Liquids like water, oil, and other chemicals do not wet a number of porous materials. Pressure can be used to force liquids into pores. Nonmercury intrusion porosimeters are based on the intrusion of nonmercury liquids over wide pressure ranges.

For extrusion porosimetry, wetting liquids are used to spontaneously fill pores in the porous materials. Liquid is displaced from pores by applying differential pressure on the sample and volume of extruded liquid is measured. Pressure yields pore diameter, and volume of extruded liquid gives pore volume and pore distribution. Liquid extrusion porosimeters are based on this principle. These instruments have additional capability to measure liquid flow rate.

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BET/Sorptometers

What are PMI BET/Sorptometers?

Sorptometers are instruments capable of measuring surface areas of porous materials, chemisorption of gases and vapors by materials, and volume of small pores as a function of diameter. Surface area is computed from the amount of vapor adsorbed at a pressure much less than the equilibrium vapor pressure. Chemisorption of a chemical is obtained from the amount of vapor adsorbed at the desired pressure. Pore volume and diameter of pores are obtained from the amount of vapor condensed in pores as a function of vapor pressure.

Various models of sorptometers possess unique features such as multiple sample chambers, detection of chemical adsorption of a variety of chemical species, ability to use many gases, capability for water vapor adsorption, low adsorption pressures, rapid measurement of surface area, means to measure low surface area, extended accuracy, and various test modes.

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Pycnometers

What are PMI Pycnometers?

Pycnometers are capable of measuring densities of materials. The true density, as well as the bulk density, are accurately measured. True density is computed from the weight and the volume of solids in the sample. The volume of solids is calculated from the loss of pressure of a known amount of gas in the sample chamber when the sample is removed from the chamber. The bulk density is computed from the weight and bulk volume of the sample. The bulk volume is calculated from the decrease in volume of mercury that the sample chamber can contain in the presence of a sample in the sample chamber. Various models of pycnometers may have multiple sample chambers, the ability to work with a number of gases, and/or greater accuracy.

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