Diaphragm Valve DIASTAR 025 FC PVC-C

  Datasheet (PDF)

The Georg Fischer DIASTAR 025 FC is a pneumatically actuated diaphragm valve built for precise throttling and tight shut-off in industrial PVC-C piping networks. It works in Fail-Safe-to-Close configuration: a high-tension internal spring package returns the valve to the fully closed position as soon as pilot air pressure is lost, protecting downstream equipment, operating staff and the surrounding plant. Factory-fitted fixed metric flanges to EN 1092-1 and ISO 7005 PN10 remove one jointing operation and speed up installation on pipe runs from d75 mm to d110 mm.

The valve body is moulded in post-chlorinated polyvinyl chloride (Agate Grey RAL 7038), a compound that combines high mechanical rigidity with resistance to concentrated acids, alkalis, oxidising agents and salt solutions, and that stays serviceable under pressure at temperatures up to 80 degrees Celsius, above the limit of conventional PVC-U systems. The actuator housing is glass-fibre reinforced polypropylene (PP-GF), chosen for mechanical endurance and external corrosion resistance in aggressive plant atmospheres. Internally, the weir-type flow geometry limits turbulence and prevents sediment build-up.

Sealing is handled by an EPDM or a composite PTFE/EPDM diaphragm rated to 10 bar, isolating the line media completely from the actuator internals; the pressure range covered is PN6 to PN10. An integrated optical position indicator shows valve status from any angle, and the pneumatic pilot ports follow standard control interfaces, so solenoid pilot valves, limit switches or electro-pneumatic positioners mount directly on the unit.

Typical duties include chemical process and dosing lines, water, demineralised and ultra-pure water treatment, electroplating and surface finishing, and microelectronics production. As an authorised Georg Fischer distributor, BigWeld supplies the DIASTAR 025 FC in d75, d90 and d110 with EPDM or PTFE/EPDM diaphragms.