Understanding the purpose and differences of the machine before determining which is better for your purpose is essential. Two important machines in their own right, the Bubble Point Tester and Gurley Permeability Tester, are used for different purposes. What are the different purposes? Let’s find out!

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Bubble Point Tester

The largest pore membrane is determined by locating the bubble stream which has been downstream. A constant bubble stream is determined, known as the bubble point, when a required pressure blows air through a wetted membrane.

Test Procedure

The test is conducted either by automatically adjusting the settings to your requirement or by manually adjusting everything. You, the tester, are always in control of everything that is happening.

The test procedure is as follows:

• A filter is wetted at one end, and gas is passed through it; the filter is then dipped in water. You need to submerge the filter completely so there are no dry spaces and water enters all the pores. Gas pressure is then blown on the membrane, making a part of it dissolve in the water. Here, the gas solubility is revealed.

• A downstream happens when the pressure is low, and the gas is released into the water. Simultaneously, as the gas pressure increases, it causes an upstream that causes the downstream’s disperse, and it rises.

• A point is reached where the water is ejected due to water from a passageway which marks the air mass flow’s path. The constant airflow that occurs is known as the bubble point.

How to Achieve Accurate Results?

To achieve the most accurate results, you need to ensure the filter is completely wet and all pores have water in them. If the filter is not wetter properly, you will witness a hasty airflow, leading to recording the wrong bubble point. Be careful of the airflow readings you note because the bubble flow needs to be constant for the correct reading. If you document the readings before stability is achieved, the reading would be wrong. You have to mount the filter correctly; otherwise, there will be an issue in the test. If you fail even after removing the casing, the filter is supposed to be disposed of, and the test needs to be conducted again.

Gurley Permeability Tester

You can accurately measure porosity, air-permeability, or air-resistance of solid, cylindrical, and sheet samples such as woven products, plastics, membranes, and papers.

The required time for a given air volume (25CC to 400CC) flowing through a standard test is of the test material is measured under light uniform pressure.

Test Specifications

There are a few specifications of the test you have to keep in mind when conducting the test. A standardized inner cylinder supplies the air pressure to measure the airflow with a specific diameter and weight. It floats within an outer cylinder, which is partly filled with oil to seal in the air. There are clamping plates present which hold the sample material. The test results are based directly and indirectly, depending on the material and test purpose.

The direst test is intended to see whether the test material resists or permits air passage. While the indirect test measures other physical properties which play a role in affecting airflow through porous sheets.

Where is it Used?

The test is used in various industries for various purposes; some of them include:

• It helps control the material selection for manufacturing and material, which can appropriately absorb liquid such as ink, varnish, and sizing.

• The porosity in materials is tested in porous bags, filters, and other materials.

• Insulating materials are tested for air resistance.

• Enable physical test regulation or strength during the manufacturing process to give materials the desired formation, appearance, or strength.

Differences!

The main difference between the two tests is that the Bubble Point Tester finds the largest pore membrane of the material. The Gurley Permeability Tester measures the porosity, air-permeability, or air-resistance of the material.