Thermal flow meter: Inconsistent readings between the field and the control room instruments
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Our factory uses thermal flow meters to measure gas flow, and we are facing the following issues: 1. The measurement values fluctuate greatly. 2. The instrument on site shows values between 400–600 m3, while the flow meter in the control room displays values between 125–300 m3. 3. The total flow rate in the gas pipeline is approximately 2000 m3, but the actual measured value is over 3000 m3. 4. A 24-volt external power supply is used, yet the internal microcontroller chip keeps getting damaged. Could some professionals please provide an answer?
Is the voltage of the 24V power supply stable when a card is inserted? Also, check whether the range settings of the control room instruments and those of the field instruments are consistent~~
The main reason for discrepancies between the on-site gauge and the DCS is different range settings on both sides
Is temperature correction applied? It’s either a problem with the transmitter
First, check whether the power supply is stable; if the microcontroller keeps getting damaged, it is definitely due to issues with the power supply. If the data does not match, it is necessary to verify whether the ranges of the equipment on site and those of the DCS are consistent. Generally, real-time flow rates are transmitted, and the method used for calculating flow rates depends on the specific signal transmission approach
I remember that in many DCS systems, the range setting works in such a way that when the range of the field instrument does not match the setting in the DCS, an alarm is generated to indicate a fault in that circuit
Check the output current to ensure it corresponds to the range setting of the on-site meter. If there are large fluctuations, check whether the supply voltage is stable and whether there are any issues with the wiring; if nothing is wrong, then check whether the flow meter is installed correctly. If nothing else is problematic, it is a flow meter fault.