Features of capillary flow porometers
While there may be some differences between the various brands and models, you will find that the machines tend to work similarly and will have many of the same features. The machine includes a needle valve, sample chamber, flow controller, flow meter, pressure transducer, sample chain spanner, support grid, O-rings, and an outlet area.
The machines are complex, but easy to use for those who understand how they work and which measurement type they should be using.
There are a number of different machines on the market from which you can choose. Before you choose a rental though, you need to determine which of the porometers will work best for your measuring needs. Consider the type of measurement you will be taking. In addition, check to see how large the machine is and be sure it will have enough space in your lab.
How capillary flow porometers work
A pressure scan is a traditional method of measuring pore size. In this method, the pressure will increase at a constant rate. You can modify the amount of pressure based on your needs visa the porometer. You then measure the gas flow through the sample. This is a fast option, and you can reproduce the results if needed. Another option of measurement is pressure step/stability. This can provide you with more accurate results, as it factors in things such as the pore length of pores that have the same diameter, and the tortuosity. The pressure is held at a constant value for a period after stabilizing the gas flow. This method is generally used in research and development.
There is also the measured first bubble point technique. This uses the largest pore size and calculates the minimum flow upon reaching a certain pressure. You would use the pressure to determine the first bubble point size.