Pressure difference meter upper and lower limit issues
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Whether it is a differential pressure level gauge or a differential pressure flow meter, when the 475 unit is connected, it displays a differential pressure value along with upper and lower limit values. I would like to know what exactly these upper and lower limits mean Are the upper and lower limits for the membrane box pressure the upper and lower limits of the pressure difference?
These upper and lower limits represent the range of pressure difference
The difference between the upper and lower limits is the range; an output is generated only when the differential pressure sensed by the diaphragm box exceeds the lower limit, and the output no longer increases once the upper limit is reached. The diaphragm box must not be subjected to pressures exceeding the transmitter’s maximum operating pressure (indicated on the nameplate), and it should also avoid being under high differential pressures for extended periods of time.
The lower limit is the basic operating standard, representing the lowest differential pressure that can be measured, while the upper limit is the maximum operating pressure, representing the highest differential pressure that can be measured
The upper and lower limits of the differential pressure value, as well as the upper and lower limits of the pressure on the diaphragm box, are indicated on the gauge; these values are not visible for 475……
On the 475 main screen, the differential pressure value (PV) shown represents the differential pressure measured by the instrument at the moment; the upper and lower limits (URV/LRV) indicate the range, that is, the pressure values corresponding to the 4-20mA outputs.
In simple terms, whether it’s a differential pressure level gauge or a differential pressure flow meter, both require a differential pressure transmitter. This transmitter has upper and lower measurement limits; for example, if they are set at 0-50 kPa, that means the highest value that can be measured by this gauge is 50 kPa. There is also a configurable range, which allows the measurement range to be adjusted according to the requirements of the specific application – it can stay within the 0-50 kPa range. For instance, it can be adjusted to 0-30 kPa or 0-20 kPa using the 475 setting, but it cannot be adjusted above 50 kPa. Lastly, there is the operating pressure tolerance, which refers to the highest pressure that the diaphragm can withstand. A differential pressure transmitter with a range of 0-50 kPa may be able to handle a working pressure of up to 25 MPa :)