I need help with issues related to using double-flange level transmitters to control flow rates
Thread Content
I’m seeking help from experts. I need an electric control valve that can regulate the liquid level of a device by controlling flow rate. The transmitter used is a dual-flange differential pressure level gauge – can this device be used to directly control the control valve?
A double-flange differential pressure level gauge outputs only a 4–20mA signal; it does not have any control or calculation functions, and the 4–20mA signal cannot directly drive an electric control valve.
If the 4–20mA drive signal required by the control valve and the 4–20mA measurement signal output by the differential pressure gauge are in a 1:1 logical relationship, then it is feasible. If not, then an adjuster needs to be added to perform mathematical calculations and output a drive signal.
Through DCS or other controllers? In short, use your brain more and get your hands moving
Direct control won’t work; you need to use a PID algorithm. If possible, introduce a DCS or PLC; otherwise, just buy a PID regulator
Are regulators integrated on the actuator of the control valve or on the transmitter? Is it still only independent?
Are there control valves or transmitters with controllers? Is it still just a single regulator?
Also, logically, what does 1:1 mean? Could you explain in simpler terms how to determine whether it is the case or not?
1. Automatic control requires three conditions: sensing instruments, a controller, and actuating instruments. 2. You already have the level gauge (sensing instrument) and the control valve (actuating instrument); now you need a controller. 3. The controller can be a common PLC or DCS system, or it can be implemented using a paperless recorder. If it’s just a single-digit automatic control loop, you can use a paperless recorder (which is very cheap).
There are transmitters with regulators, but they are generally based on bus control systems. I don’t think it’s very likely that you’ll apply it. Let’s solve it as mentioned in 7#.