Top Considerations for Choosing the Right Hose

Hose choices abound in the world of specialty gasses, which can make it hard to select the best option. With that in mind, here’s a quick primer on things to consider when choosing a hose that will best suit your needs and perform reliably over time. (Related: Flexible Hoses Part 1: Understanding the Basics)

Pressure: The average working pressure of a hose should be well above the required maximum pressure of your application. 

Molecular Weight: Consider the molecular weight of your material. For example, hydrogen and helium have the smallest molecular weight, and therefore present a higher risk of permeation loss. A larger molecular weight presents less of a permeation risk.

Permeation: When permeation is a concern, consider using an all-metal, ETFE, or PTFE post sintered type hose. Be sure to confirm that the flow rate is below the suggested threshold level. (ETFE and PTFE post sintered hoses reduce effusion by approximately 75%.)

Purity: Hoses that effuse gasses can also diffuse gasses, which can introduce contaminants that could affect the high purity gas stream. All-metal hoses and PTFE post sintered hoses reduce effusion and diffusion. 

Static State: Gasses in a static state (off hours and weekends, for example) are at risk of effusion. Typically the amount lost is minimal, but can add up over time. Consider a low effusion hose for applications where gas will be trapped inside the hose for longer periods of time.

Fill Manifolds: Hoses used on fill manifolds are typically cycled (attached and disconnected from the cylinder) several times a day, which exposes the hose to continual flexing. Disconnection opens up exposure to open air. As a result, permeation of a fill manifold is of minimal concern. PTFE hoses work well in this application. 

Laser Cutting Systems: Using the wrong hose to supply a laser can be detrimental to the operating efficiency of the laser. Depending on the permeability of the hose, a high permeation hose will contribute contamination, resulting in increased downtime and ultimately, the quality of the cut.

Dynamic Stress: Dynamic stresses happen during handling, transport, or storage of gases, and are the largest contributors to hose failure. Each hose type has different limitations for handling dynamic stress. For example, all-metal hoses should never be over-bent, while corrugated hoses may not handle higher flow rates as well. Always ensure the hose can handle the set thresholds for your specific application to prevent premature failure or damage.

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