VALVE MAGAZINE Summer 2024

VALVE BASICS

USE OF POLYMERS IN VALVE BODIES Plastic bodies are not as widespread as polymer valve seats. They are usually specified for one of the distinct advantages they offer, including: • Lower cost of some polymers • Ability to be injection molded • Superior resistance to acids, bases and certain corro sion attack modes • Ability to provide superior ultra clean technology by avoiding metal ion contamination, as is required in semiconductor applications and related fields • Ability to be gamma irradiated for single-use biopharm and medical applications • Ability to be easily welded to flexible tubing for biopha rm and medical applications

Three single use polymer back pressure regulators provide transmembrane pressure control in a Single Pass Tangential Flow Filtration (TFF) biopharmaceutical application.

A low flow back pressure regulator in polyether ether ketone (PEEK) can be a good selection for ultra-pure water applica tions involved in semiconductor manufacturing.

At the same time, these advantages must be weighed against potential disadvantages of plastic valve bodies. Depending on the specific polymer, these may include: • Pressure limitations • Temperature limitations • Inability to reliably predict stress failure, requiring extra consideration for pressur ized gas above 7.25 psi (0.5 bar) pressures • Lack of structural robustness, requiring extra support • Susceptibility to solvent attack for certain polymers • Potential for static discharge in special applications • Environmental and health concerns

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VALVE MAGAZINE

SUMMER 2024