Best material for low permeability flexible tubing?


I hope I am posting this to the right group.

I am looking for material advice for 1/8" ID flexible tubing for inert and dry gases up to 50psi. Lenght will not be more than 8in. Temperature range about 0 to 200F. The tubing will be connected between a monitoring pressure transducer and a metal barbed fitting.

I have tried silicone (platinum and peroxide cured) but it has high permeability and Tygon R-3603 sets badly on fittings losing its seal as time passes. The application will require the tubing to be connected for years and will not be removed once it is installed. I thought of using metal tubing instead but that is not an option in this case because of vibration.

I found a nice reference for tubing permeability in the Cole-Parmer

2003-2004 catalog (page 1910). Some materials have very low permeability but it is difficult to tell if they will work with my application. The description of each tubing does not mention how well it grips onto fittings.

Is there a material that would have strong gripping and flexibility like silicone (or better) but lower permeability like R-3603?

Thanks for any info,


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If you can substitute another fitting for the hose barb, you might consider a bellows hose. This is a long metal bellows, which would have no problem handling pressure or vibration.

Reply to
Mark Thorson

How about a hose clamp on the outside of the Tygon? If it sets, turn the clamp a smidge tighter every once in a while.

Dave dvt at psu dot edu

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