SISTO-C Pneumatically operated Valves Features ? Piston actuator ? Valve bonnet in compact design, actuator housing and valve bonnet manufactured out of one part ? Stainless steel stem ? Clear visual position indication by red plastic indicator – well visible all around ? Stainless steel compressor ? Floating nut ? Spring chamber venting by operation hole ? Spring to close – air to open ? Stainless steel spiral spring support for MD 65 and larger Variants ? Spring to open – air to close ? Air to open – air to close ? Two-stage-actuator ? High temperature design with FKM/FPM seal (Recommendation: >= 80 °C measured at actuator housing) Optionen / Options ? Limit switches ? Positioner ? Adjustable travel stop