Piston

Piston check valves are used to prevent reverse flow in industrial systems handling water, steam, condensate, gases, compressed air, and process liquids. Operation is based on a piston, disc, or axial element that opens under forward differential pressure and returns to the seat when flow decays or reverse pressure develops. The category includes in-line, angle, Y-pattern, wafer, axial/nozzle, foot check, and pressure seal designs from ARI, Brandoni, ICP, Gestra, Fluitek, Cast Flow, Valvosider, Genebre, and Tassalini.

Valve selection should be based on fluid type, flow rate, allowable pressure drop, cracking pressure, installation orientation, flow pulsation, water hammer risk, seat leakage requirements, and maintenance access. In steam and condensate service, the installation point must be checked for drainage and potential condensate accumulation. In pump discharge lines and high-velocity systems, piston mass, spring loading, and closing time directly affect hydraulic shock and transient load in the pipework.

Available standards include DIN and ANSI, with pressure ratings from PN6 to PN420 and Class 150 to 2500. End connections include BSP, NPT, ISO 228-1, flanged, wafer, socket weld, butt weld, and Victaulic. Body materials include cast iron, ductile iron, cast steel, forged carbon steel, low-temperature carbon steel, stainless steel, and austenitic stainless steel, including EN-JL1040, EN-JS1049, 1.0460, 1.0619, 1.4408, ASTM A105/A105N, ASTM A182 F316, ASTM A216 WCB, ASTM A217 WC6, and ASTM A351 CF8M/CF3M. Seat options include metal-to-metal, PTFE, NBR, EPDM, FKM/FPM, and Stellite, selected according to temperature, shut-off class, and media compatibility.

For high-pressure service, pressure seal constructions are available such as Valvosider PN100-PN420 and forged Genebre Class 800 valves with ASTM A105N body, NPT or socket weld ends, and stellited stainless seat. For hygienic or stainless process applications, Tassalini valves are manufactured in AISI 304L or 316L, suitable for horizontal or vertical installation, with maximum working pressure up to 10 bar.