Zero drift issue of Yokogawa pressure transmitters
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A tank with a height of 1100 mm was measured using an EJA310; the liquid level was kept between 900 and 1100 mm, and the transmitter’s range was set to 0-11 KPA (to directly measure the pressure at the bottom). It was found that after some time of use, the zero point shifted and became negative. The problem persisted even after replacing the transmitter, and it’s not clear what the cause of this issue is
310A？ Gauge pressure transmitter?
What medium is the liquid, and does it crystallize? Does temperature affect the density of the medium? Given that you’ve changed the transmitter, it seems unlikely to be related to the transmitter itself; instead, look for causes in external factors, the medium, the measurement method, the location of the measurement point, and other such aspects.
It’s definitely not a problem with the transmitter; your measurement range isn’t that small either. It’s understandable if there’s a slight drift of a few water columns, but if the drift is that large, the issue must lie somewhere other than the transmitter. Focus on studying what special circumstances exist in the process.
I also don’t think it’s a problem with the gauge; based on our factory’s experience using EJAs, these instruments have quite good reliability.
Our factory uses vacuum pumping to measure the vacuum level, with the DCS setting the range at 0–10 KPA. The pressure transmitter used on site is the Yokogawa EJA type, with a range of 0–10 KPA. How is the range set? Question 1: Is there an issue with the transmitter selection (it shows Er03 or Er07 when connected to the atmosphere; what does it show in the control room?) 10KPA。 The originally set range was 0–10 KPA, with a current reading of 21.576 mA). Question two: Is there an issue with the DCS settings? For a range of 0–10 KPA, the value should theoretically be much higher than this. The same pipeline uses an ABB pressure transmitter, with the range set by the DCS at 227 KPA. The transmitter’s range is from –99 to 258 KPA. I set it as follows: the zero point is set at –101.32 KPA, and the range is 126.68 KPA, so that it matches the DCS settings. After normal operation, the control room displays 0.1 KPA. Is this normal?
1. The vacuum level must be measured between -xx----+xx kPa； 2. The abb transmitter is functioning properly, indicating that the maximum range of the gauge is 328 kPa; therefore, there is an issue with the range selection for the Yokogawa EJA transmitter.
It has nothing to do with the gauge; it’s probably due to an incorrect measurement method. Is the tank at atmospheric pressure and open? What is a medium? Pay special attention to checking for leaks at the pressure source.
It is a gauge with a range of 0–10 KPA; the tank is vacuumed, and the medium should be air. There is no leakage. At normal pressure, the fault codes ER03 and ER07 are displayed. I don’t have the manual, so I don’t know what it means.