Issues regarding changing the range of a pressure transmitter for measuring liquid levels.
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I would like to ask whether it is necessary to perform zero and full-scale calibration after changing the range of a pressure transmitter on-site. For example, in a tank with a capacity of 0-6 meters, if the internal water pressure ranges from 0-60 kPa, and now another fluid is used whose density is 1.2, resulting in a pressure range of 0-72 kPa, then if I change the transmitter’s range to 0-72 kPa, do I still need to carry out zero and full-scale calibration? I would appreciate some guidance on this matter; or perhaps no calibration is required at all, since when the fluid with a density of 1.2 fills the tank to a height of 6 meters, the pressure will naturally be 72 kPa?
Calibration is required; only after calibration can it be determined that the range you have adjusted is correct.
Just change the upper range limit; leave everything else unchanged, including the position of the gauge. It’s just to increase the upper limit by 12 kPa.
Simply adjust the range. If you’re concerned about discrepancies, check whether the zero point is accurate; if not, it needs to be reset (it’s best to remove it and check for any dirt)
Sir, I’d like to ask you for some advice again. For example, if the pressure inside the tank is 30 kPa, and I change the pressure range to 0-100.0-200.0-10000.0-30000, will the pressure transmitter on site still display 30 KPa? In other words, what principle does the on-site display rely on? I know that remote transmission uses a 4-20 mA signal; but what determines the value displayed on site? Please advise, sir.
Sensors also have specific range limits; it depends on the upper and lower limits set by the transmitter at the time of manufacturing, and they cannot be modified as one wishes. If a sensor is used to measure 30 KPA when it’s designed for 30 MPa, the accuracy will not be good. Similarly, trying to use such a sensor to measure high pressures of 30 MPa when it’s intended for low pressures of 30 KPA can also damage the sensor. 4-20mA corresponds to the upper and lower limits of your range.
By changing the range, you are only altering the pressure value corresponding to the 4-20mA output current. The measurement range that the transmitter can handle is predetermined at the time of manufacture, and it is not affected by changes to the range setting. As long as the pressure measured by the transmitter is within the range you have set, it will display the measured pressure value correctly. Originally, the range was 0–120 kPa; 30 kPa corresponded to 8 mA. After changing the range to 0–240 kPa, when the pressure is still 30 kPa, the corresponding current is 6 mA.