Questions about valve positioners
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I’ve never really understood the concept of valve positioners. The book says that their function is to increase the force applied to the valve; so it should be possible to operate the valve without a valve positioner, right? Or in other words, when should it be used and when can it be considered unnecessary? Also, how is the valve positioner tuned on-site? For example, if the positioning is inaccurate, how can it be corrected by adjusting the linkage of the valve actuator? Are there specific steps? Thank you all!
It depends on what brand/model/principle the valve positioner is, etc
The best way is to read the device’s user manual; once you understand it, your problem will be solved. For reference only.
What book are you reading? Nonsense! The function of the positioner is to control the valve opening degree, thereby enabling regulation. Increase valve strength? If any, it’s only supplementary.
“Valve positioners can increase the output capacity of control valves, reduce delays in the transmission of control signals, speed up the movement of the valve stem, improve the linearity of the valve, overcome frictional forces on the valve stem and eliminate the effects of unbalanced forces, thereby ensuring the accurate positioning of the control valve. ” This really isn’t nonsense.
That’s just possible; I haven’t denied it either. It’s not right to talk about it separately!
I would like to ask: for example, if I want to choose a pneumatic control valve, is it necessary to use a valve positioner as well? Is it okay not to have it, or is it better to have it?
A control valve certainly needs a positioner. These days, they are usually smart locators.
If it doesn’t have a positioner, how can the valve know how wide you want it to open?
I also feel like this guy hasn’t entered the industry yet: lol