Always Consider the Chemical Environment in Your Flow Path

Mar 7, 2022 by IDEX Health & Science

Regardless of what type of fitting you choose, if incompatible chemicals contact a fitting, its ability to seal and its thread integrity may be compromised.

Additionally, since most fittings comprise two pieces — the nut and the ferrule — you should consider chemical compatibility with both the nut and the ferrule material. For example, you may have a fingertight fitting with a PEEK polymer ferrule and a Delrin® nut, and you need to make a tubing connection in a LC-MS application where a low concentration of TFA (trifluoroacetic acid) is being used. In this type of application, the PEEK ferrule will perform adequately.

However, if the solution comes in prolonged contact with the nut (e.g., if some of the chemical solution got on the port’s threads when the fitting was previously loosened), eventually the polymer would erode away at the point of contact. The fitting’s integrity would then be compromised — resulting in a leak!

There are many sources for up-to-date information regarding chemical compatibility including the manufacturer of the fittings you have chosen to use. You can also view our Chemical Compatibility Guide. We highly recommend you refer to one of these sources before finalizing your fittings selection.

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