Relationship between current value and valve opening degree
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1. If the valve opening degree specified by the DCS is 0, what are the current values for air-operated shut-off valves and air-operated open valves? 2. If the valve opening value provided by the DCS is 0, could the current for a air-operated valve be 4 milliamps? If it is 4 milliamps, under what circumstances is that 4 milliamps? 3. Is there a corresponding relationship between the opening degree displayed on the locator panel and the current value? 4 milliamps corresponds to 0 degrees of opening, and 20 milliamps corresponds to 100 degrees of opening?
4 milliamps corresponds to 0 degrees of opening, while 20 milliamps corresponds to 100 degrees of opening
For the air on valve, 4 mA corresponds to 0% fully closed, while 20 mA corresponds to 100% fully open. For the air shut-off valve, 4 mA corresponds to 100% full open, while 20 mA corresponds to 0% full closed. The air shut-off valve can also be adjusted to full close at 4mA and full open at 20mA using the positioner parameters. The air control valve can also be adjusted to 4 mA for full open and 20 mA for full closed via the positioner parameters. All of them can be set.
Under normal circumstances, the air-operated valve is set to 100% open on the system side, the current at the field side is 4 milliamps, and the valve is in a fully open state at the field location. However, if the system side inverts it, the opening degree can still be set to 100, with a current of 20 milliamps at the field side. Right? ?