Problems with single-flange level gauges
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It is a single-flange level gauge; the display shows 0%, but the output current is 4.15 mA. The range settings are 0–50 KPa. After performing a zeroing operation and a D/A calibration, the same result is obtained. The same issue persists even after replacing the entire circuit board. Could someone experienced help identify what the problem is? Could it be a problem with the sensor?
Does it make no sense if the circuit board is replaced? How was the current value of 4.15 obtained? Multimeter? Manual controller? Let’s check other aspects.
If I remember correctly, the handheld controller has an option for adjusting the output, allowing you to make such adjustments without putting any stress on the diaphragm of the level gauge.
The liquid-contacting flange was not removed, so it remained connected to the atmosphere, and a certain pressure remained inside the container. Is it new or in use? Is the altitude in your area above 1000 meters? What is the operating temperature?
Could it be that your multimeter is the one that’s broken? The output current is independent of the sensor.
Two multimeters were used, and the currents and pressures measured by them matched those of other level gauges.
The level gauge was completely removed and left exposed to the atmosphere.
The hand controller shows 4mA, but a multimeter reads 4.15mA. It was only after removing the component that the meter indicated 0%, while the main control unit showed a value other than 0; that’s when this issue was noticed.
Multimeters can also have errors; if the display on the control unit shows a value other than zero, could it be that there is an error with the safety barrier or some other component?
The current displayed on the handheld controller is obtained by reading the internal signal of the pressure transmitter via HART. Therefore, it can be concluded that neither the sensor nor the circuit board is faulty. The problem lies in the current output module. I don’t know what brand your pressure regulator is. Yokogawa’s current output module is soldered to the enclosure.
For the Rosemont model, the terminal block at the back is likely used only for power supply; even after replacing the entire circuit board related to the meter display, it still doesn’t work.