Gas and liquid permeability of polymer materials - Leak mechnism identification

By applying the same techniques used for permeation measurements we can help you identify why your product leaks

Generally speaking, there are 3 mechanisms for leakage of gas

•  Large hole
• Gas dissolves on polymer
• Gas diffuse thru one or several thin channels

By applying a mixture of gasses in or on one side of your product we can determine the mechanism by measuring the rate and composition of the "leak" gas. The two gases are chosen to be a high and low permeable gas and at the same time a light and heavy molecule.

• With a “large” hold the composition will be the same
• If the transport mechanism is by dissolving the gas in the polymer part of the product. It can be identified in the following way: a mixture with significant permeability is used. The relative concentration of the escaping gases is measured are compared to the permeation of the two gases.
• If gas diffuse thru a thin channel the smaller molecule will move more easily, and more will leak.

Collecting the escaping gas can be challenging. By measuring the dimensions of the suspected leakage point, we have good experience in using 3D-printet ‘cups’ to collect the gas. Usually fitted with an O-ring to keep them gas tight. The ‘cups’ take the place of the low pressure or downstream side of the permeation cell. Both amount and composition of the escaping gas can be measured.

Examples of 3D-printed cups for collection of leaking gas. One with axial fit and one with radial fit. These were made to fit a specific product. 3D printing is a flexible and fast way to make it fit a specific product.