Stainless Steel Diaphragm Valves for the Chemical Industry

In no other area of application are valve requirements as varied as in the chemical industry. Where in-line solids flow in the media as well as for sterile applications, diaphragm valves are the first choice. Stainless steel valve bodies offer very good resistance to both internal and external corrosive attack.

GEMÜ offers stainless steel diaphragm valves in various body and end-connection versions. 1.4408 and1.4435 body materials lined with PFA (Perfluoroalkoxy) offer further protection when used for industrial applications with extremely cor-rosive media. Stainless steel or chemically-resistant plastic actuators, equipped with PTFE shut-off diaphragms ideally combine with these bodies.

Position indicators, combi-switchboxes, Field bus interfaces, as well as position and process controllers are optional equipment for all pneumatic actuators. The valves are thus suitable as control valves in critical applications.

Even without additional linings stainless steel bodies are more resistant to cor-rosion than SG iron bodies with damaged linings.

Depending on nominal size and diaphragm type, GEMÜ PFA-lined diaphragm valves close up to operating pressures of 6 bar (dynamic sealing). These valves reliably achieve temperature resistance of -18°C to +90°C for liquid media in continuous operation and up to 150°C intermittent steam operation. Flange connections are in accordance with EN 1902 or ANSI Class 125/150.

PFA is resistant to strong mineral, oxidising and inorganic acids, bases, halo-gens, metal salt solutions, anhydrides, organic acids, as well as ketones, es-ters, ethers, aldehydes, alcohols, amines and hydrocarbons. Among PP, PTFE or PVC, PFA has the highest resistance to elevated temperatures.

GEMÜ injection-moulds the PFA-lined valve bodies. Exactly defined geometric features, uniform wall thickness, high quality and reliable process repeatability are some of the advantages of this complex lining process. Additionally, PP and Hard Rubber linings also use this injection-moulding method.

• GEMÜ valve bodies exclusively feature top quality materials from reputable suppliers.
• Maximum application reliability is ensured through individual testing of every single component.
• Especially selected certified foundries produce the metal bodies.
• Injection tools for the plastic lining are made in-house with GEMÜ precision Technology.
• GEMÜ plastic linings are subject to strict quality control checks, including spark testing.
• The body injection point, located below and through the weir, ensures that the plastic lining will not separate from the body under industrial vacuum conditions.
• The plastic lining is axially anchored to the inner diameter at the metal/plastic transition point, avoiding tension damage during heat expan-sion.