In high differential pressure conditions, the valve spool in control valves can rotate. Therefore, how should the issue of preventing rotation be taken into account during the valve design phase? And how can it be calculated and analyzed to determine under what operating conditions the valve spool will rotate?
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As the title suggests, I have been working on the maintenance of control valves for some time now, and I have noticed that in most pneumatic control valves used in practice, the valve stem does rotate. In severe cases, the feedback rod used to detect movement can break or come loose. Some valves are designed with coupling guides to prevent excessive rotation of the valve stem, while other valves lack any such protection against rotation. So, how can one determine during the design phase whether a valve needs such protection against rotation? And how can one calculate the amount of deflection force that the valve stem is subject to?
It is recommended to use a video to explain each individual issue, as valves vary from one another.
It is a common occurrence for the valve core (valve disc) to rotate on its own under the action of the medium during the adjustment process. Most valves lack a self-rotation prevention mechanism because no consideration was given to this aspect during the design phase, and neither the product standards nor the process design (by the purchaser) specify any requirements in this regard. It is difficult to determine directly from the appearance whether a anti-rotation mechanism is present; in cases of high flow velocity and pressure differences, it is possible to request this from the manufacturer.
What was said on the 3rd floor is correct. It is related to flow rate and pressure.
Given the known operating conditions, can we calculate the deflection force exerted on the valve by the medium?
Based on the structure of the valve and taking into account the fluid field, certain simulation calculations can be carried out; however, accurate data can only be obtained through practical testing