Why Quarter-turn Valves 'Pop' Open

摘要

We've all seen this situation: A quarter-turn valve is in the closed position. A pneumatic actuator applies an opening torque that exceeds what's required to begin to open the valve. Suddenly, the valve "jumps" or "pops" open to as much as 45 degrees or more, resulting in a sudden surge of potentially disruptive flow. Why did this occur and how can we avoid this phenomenon?