Sulfur hexafluoride (SF6) is an inorganic, colorless, odorless, non-flammable, extremely potent greenhouse gas, which is an excellent electrical insulator. The greenhouse effect of SF6 could be 25, 000 times of that of carbon dioxide. And even worse, SF6 can stay active in gas for more than 3400 years.

Today over half of SF6 produced in the earth each year is used in electrical industry. More than 80 percent of those SF6 are used in manufacturing of high-voltage electrical appliances without proper handling and recycling process. As a result, the residual SF6 reacts with the water inside the equipment and insulation materials thus generating hazardous substances which may cause pollution to the environment and influence the performance of the electrical appliances and do harm to human health.

In many electrical appliances, rubber materials are used as insulation materials which can also prevent the SF6 from permeating through to the external environment. Therefore, it is necessary to test the barrier property of rubber materials against SF6 for the manufacturers of electrical appliances.

This article provides a test method of gas permeability of SF6 against rubber material for your reference. The test specimens are rubber sheeting provided by one manufacturer and the testing instrument is Labthink’s VAC-V2 Gas Permeability Tester.

Figure 1. Insulation Rubber Materials used in Electrical Appliances

Figure 2. Labthink’s VAC-V2 Gas Permeability Tester

Labthink’s VAC-V2 Gas Permeability Tester adopts differential pressure method where the sample is mounted in a gas transmission cell so as to form a sealed semi-barrier between two chambers. One chamber contains the test gas at a specific high pressure, and the other chamber, at a lower pressure, receives the permeating gas. The gas permeability of the sample can be calculated on the basis of pressure change.

The tests can be performed according to the following procedures.

Connect the SF6 gas supply to the instrument.

Set test parameters. The test temperature should be 23℃ and the test humidity should be 0%RH.

Run the software and set parameters. Then start the tests.

The test results will be automatically calculated and displayed after tests.

Turn off the gas supply and switch off the instrument.

For more details about VAC-V2 Gas Permeability Tester, please visit www.labthink.com

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