Considerations for Choosing Chemical-Resistant Tubing
Selecting the appropriate material for your application is critical for successful product realization. Chemical compatibility is one of the first aspects to consider when selecting a material, and can differ significantly. So, let’s take a look at some of the more common plastic tubing materials for precision fluidics.
There are many things to consider when selecting materials for your fluidics system. In this article we’ll specifically focus on chemical compatibility, but don’t forget to read our other articles for more information in our Engineers’ Center like, “PLASTIC TUBING MATERIALS GUIDE: PTFE, FEP, PFA, PEEK AND PVC”
Common Chemical-Resistant Tubing Materials
Fluoropolymers are common choices for chemically resistant tubing. It is due to the strength of the Fluorine-Carbon bond within the fluoropolymer chain that provides incredible inertness. These bonds are so tight and enduring that they don’t allow other atoms or molecules to separate them. But although they are common choices, they aren’t the only choices or even the best choices when considering all performance and build-cost requirements.
Some commonly used chemical-resistant tubing materials include:
- Perfluoroalkoxy Alkane (PFA)
- Fluorinated Ethylene Propylene (FEP)
- Polytetrafluoroethylene (PTFE)
- Poly Ether Ketone (PEEK)
- Polyvinyl Chloride (PVC)
PFA Tubing Chemical Resistance
Flanged fittings are best suited to most applications. They are the least expensive option—and they are the best option if the user intends to disconnect the tubing and reconnect it for use. Flanged fittings can only be used for fluoropolymer tubing such as FEP or PTFE.
FEP Tubing Chemical Resistance
Being a fluoropolymer PFA, FEP, and PTFE are all incredibly chemically inert. FEP resists almost all known chemicals except molten alkali metals, elemental fluorine, and fluorine precursors at elevated temperatures.
PEEK Tubing Chemical Resistance
PEEK is often selected for it’s biocompatibility in addition to its chemical inertness. PEEK exhibits excellent resistance to a wide range of organic and inorganic chemicals. Some chemicals which will attack PEEK are
concentrated acids, bromine, and chlorine. However, PEEK tubing can safely withstand 20-30% nitric acid when passivating a system.
PTFE Tubing Chemical Resistance
PTFE is one of the most inert materials known. It is resistant to virtually all chemicals except for alkali metals and Fluorine or Monoethanolamine at elevated temperatures.
PVC Tubing Chemical Resistance
PVC is lower in cost an does an excellent job of handling many strong acidic and alkali solutions. However, PVC should not be used with esters, ketones, ethers and aromatic or chlorinated hydrocarbons. PVC will absorb these substances and this will lead to swelling and a reduction in tensile strength
Other Important Factors when Selecting your Chemical-Resistant Tubing
There are many things to consider when selecting materials for your fluidics system. Working temperature, working pressures, insulation properties, thermal properties, tensile strength, strain resistance, cost, and processing capability are all important factors in material selection.
In this article we’ve specifically focused on chemical compatibility, but don’t forget to read our other articles for more information in our Engineers’ Center like, “PLASTIC TUBING MATERIALS GUIDE: PTFE, FEP, PFA, PEEK AND PVC”.
Ready to get started? Find the chemical-resistant tubing material best for your application.