In what situations is it necessary to install a handwheel on a pneumatic valve? According to the specifications
Thread Content
In what situations is it necessary to install a handwheel on a pneumatic valve? According to the specifications
SH/T 3005-2016 \"Code for Selection and Design of Automation Instruments in Petrochemical Industries\" 10.1.12 The selection of accessories for control valves shall comply with the following provisions: b) Handwheel mechanisms are suitable for use in the following situations: 1) Control valves that do not have shut-off valves or bypass valves； 2) Handwheels cannot be used for the mechanical positioning of valves; except in special cases, no other methods are suitable for mechanical positioning ；
According to relevant specifications, hand wheels must be installed on pneumatic valves in the following situations: 1. When the air supply fails, manual operation via the hand wheel can ensure the normal operation of the system. 2. During debugging, in order to facilitate precise control of the valve opening, fine adjustment is required using a handwheel. 3. When the automatic control system fails and cannot output control signals correctly, manual control can be achieved using a handwheel. 4. For valves that are opened and closed frequently or require precise flow control, a handwheel should be provided for emergency operation. In general, the handwheel is provided to allow switching to manual control in case there are problems with pneumatic control, thereby preventing greater damage to the system. .
It can be set for those other than SIS; it’s not necessary for SIS.