Understanding Hose Permeation in Industrial Fluid Systems
Learn how hose permeation can affect the performance, safety, and reliability of industrial fluid systems. Permeation is the movement of gas molecules through a hose material and is an important consideration when selecting nonmetal hoses made from materials such as PTFE and PFA. Understanding how factors such as temperature, pressure, media type, hose construction, and material selection influence permeation rates can help reduce product loss and support safer system operation. In this video, you'll gain a foundational understanding of permeation and why it matters in hose applications. To deepen your knowledge of hose selection and performance, explore Swagelok’s resources and hose management that can help improve system reliability.
Video Transcript
In industrial fluid system applications, hoses can present an ideal alternative to rigid materials such as piping and tubing. Hose lends itself to convenient bending and routing. This enables system designers to eliminate many of the connectors required when using rigid materials, which can help lower the cost of materials and labor, reduce risk of leakage, minimize pressure drop changes, and more.
There are various hose characteristics to consider when making a selection. If you’re seeking a nonmetal hose, one key characteristic is the hose’s potential permeation rate. Permeation is the flow of gas molecules through a solid material. All materials are permeable to a degree, but in industrial hose applications, permeation is important to consider when using PFA and PTFE materials. For this reason, it’s important to understand the factors that influence permeation rates and how important permeation resistance is in your application.
Gas permeation can present a major safety risk. If your gas is explosive or toxic, the surrounding area can quickly become very dangerous. Even if your gas is inert, an enclosed area could become hazardous as the escaping gas displaces oxygen in the air. In open areas, permeation can lead to expensive losses in gas.
Several operational factors can impact the permeation rates of your hose, and different hose materials will respond to those factors differently. Hose surface area, which is its length times its diameter, has a linear effect on total permeation rate. The greater the surface area, the higher the potential for permeation.
At higher pressures, gas molecular count increases, causing greater potential for permeation. Permeation rate is linear with pressure and molecule count. Higher temperatures cause molecules to move faster and, therefore, to permeate the material faster. Core tube wall thickness will determine how easily gas molecules can find a path to permeate the hose. Molecules will move through a thinner wall more quickly.
Finally, sintering, applying a heat treatment to the core, can tighten the bonds of a soft core hose, making permeation rates lower. For example, post-sintering a PTFE core will maximize permeation resistance.
Permeation should always be considered for applications with small molecules, such as helium and hydrogen. It may also be a greater concern in high-heat, high-pressure applications. However, it may not be a significant concern in other applications. If in doubt, work with your hose supplier to help identify your needs and guide you toward the right hose choice.
If you are interested in learning more about permeation and how it may impact hose selection in your facility, our Swagelok Hose Essentials training is a good starting point. Our hose advisory services team can also work with you to provide guidance on hose selection, installation, inspection, and maintenance procedures to improve hose life and performance.
For more information about Swagelok hose advisory services, contact your local authorized Swagelok sales and service center today.
