Manual valve operation in absence of control pressure
Cameron fusible manual hold-open device is designed for use on actuated gate valves of 3-in and smaller diameter and internal valve pressure to 10,000 psi. The hold-open device is used to manually operate the valve when control pressure is not available.
This modification of the traditional hold-open device includes a fusible plug for protection under catastrophic conditions. The fusible manual hold-open device threads directly to the top of the actuator. Rotating the handwheel produces enough torque to overcome actuator spring force and mechanically open the valve.
The main advantage of using a fusible hold-open device is additional safety system shut down protection during extended wireline operations. If a fire-based catastrophe occurs, the fusible manual hold-open device will melt from exposure to the extremely high temperatures, allowing the surface safety valve to return to the "fail-safe" position. We do not recommend leaving the device on actuators for extended periods.