Valve position feedback for the on/off control valve?
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I recently purchased a switch-controlled valve that has three control modes (valve open, valve closed, valve stopped). The valve position feedback signal is provided by the contact signals of two limit switches (for full open and full closed positions). We know that the valve position feedback signals when the valve is opened and closed are the contact signals of the two limit switches. So the question is: what is the valve position feedback signal when the valve is in the middle position? It’s mainly because I’m on leave outside and haven’t participated in the debugging yet!
Is the valve stuck in the middle position? Adjust the control valve?
No signal; the feedback signal for the on/off control valve you purchased is binary – there are only signals indicating when it is fully open or fully closed.
Does that mean that after leaving and closing the limit positions, no contact signal can be detected?
If that’s the case, it becomes a bit inconvenient for operation
It is possible for the switch valve to remain in the middle position; for example, if the valve gets stuck by foreign objects and cannot be opened or closed to the correct position, it will display messages such as fault or error, and turn yellow.
If the process needs to operate at an intermediate position, it’s difficult to tell; the status may display as abnormal or yellow
No, it’s a on/off valve that can be stopped in the middle position
Is this a three-way two-position valve? Such position feedback is not available. One can be customized according to the valve type.
Specific instructions should be provided on the DCS screen according to the conditions of the process. Indicates that it cannot be opened or closed fully; provide a color code for this.
This should be a valve equipped with a three-stage cylinder, with the middle position being preset; it is possible to customize limit switches for 3 positions (off – middle position – on). Generally, this type of valve is used in loading systems