The Siemens 3SF5811-2AC10 is an AS-Interface emergency stop pushbutton with a 22 mm mounting diameter, rated for 26.5–31.5 V DC. It uses a rotate-to-unlatch mechanism and provides positive opening of the contacts — meaning the NC contacts are mechanically forced open when the actuator is pressed, even if they weld shut. That's the core safety function: it guarantees the circuit breaks under fault conditions.
IP67 and washdown duty
Rated IP67, so the housing and actuator seal against dust ingress and temporary immersion. That makes this unit suitable for food-and-bev washdown zones, outdoor conveyor lines, or any area where hose-down cleaning is routine. The metal enclosure and metal holder add mechanical robustness for high-vibration environments — tested to 5g at 20–200 Hz per IEC 60068-2-6.