the first. What type of shut-off valve is the handwheel mechanism installed on?
First of all, we should clarify the question of what type of shut-off valve is the handwheel device installed on. The hand wheel of the electric actuator is its standard configuration, and there is no question of whether to set the hand wheel, so the dispute is whether the pneumatic valve needs to set the hand wheel mechanism.
second. What is the role of the handwheel mechanism?
1. When the air source signal or electrical signal fails, or when the main components of the actuator (such as diaphragm, spring, seal, transmission, etc.) are damaged, the automatic operation should be changed to manual operation, and the handwheel can be used The mechanism continues to maintain the regulating function of the regulating valve.
2. The handwheel mechanism can also be used as a limiter for regulating valve stroke. (Limit function)
3. The handwheel mechanism can improve the reliability of the operation of the regulating valve. If a bypass is added to the regulating valve, the investment cost is large, the area is large, and the cost is higher when the caliber is large or precious metals are used. It is more cost-effective to use the handwheel mechanism regardless of the investment cost or floor space.
third. Does the shut-off valve need to be equipped with a handwheel mechanism?
Whether the shut-off valve is equipped with a handwheel mechanism, there is no accurate answer, mainly due to consideration of different application scenarios, there should be a trade-off relationship.
1 Judging from the requirements of HG/T20507-2014, it is mainly centered on interlocking to prevent the design of the handwheel from affecting the execution of interlocking actions.
2SH/T3005-2016 does not specify whether it needs to be set, but it puts forward some basic constraints.
3 Generally speaking, the shut-off valve related to the safety interlock should not be provided with a handwheel mechanism. For other shut-off valves that do not participate in safety interlocking, from the perspective of process production, according to the importance of process control, there is no bypass and the failure of the valve will not cause production paralysis within a limited controllable time Next, you can add a handwheel mechanism. In this case, considering that there may be personnel misoperation during normal operation, manual closing of the valve, etc., you can consider adding corresponding management measures, such as handwheel locking or handwheel removal.
