Position drive, esp. for control and blocking valves - has safety mechanism with expansion and hardening material moving valve actuator to safety position above limit temp.

摘要

The position drive safety mechanism automatically places an actuating element (16) in a safety position, esp. a closure position, at a limit temp. above the normal temp. range, esp. under combustion conditions. A swelling material which forces the actuating element in the direction of the safety position when it expands increases its vol. when the limit temp. is exceeded by forming hollow chambers. The material can be a paste which hardens after expansion. USE/ADVANTAGE - Fireproof position drive safety mechanism in field of automation. Securely maintains safety position of control and blocking valve or similar for long period using simple arrangement.