Installation of the pressure gauge
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I believe everyone has seen the installation of pressure transmitters like this. I’m curious to know how people consider this error factor. The transmitter’s range is 5 MPa, with an accuracy of 0.075%. The vertical height between the pipes is around 2 meters, and no condenser tank is used; as a result, liquid injection causes an error of about 0.02 MPa. The pressure during operational processes is roughly 2 MPa, so the error caused by liquid injection isn’t that significant, but it still exists. I’d like to hear everyone’s opinions on this error – feel free to share your thoughts
This post was last edited by ROSEHOOD on 2010-7-2 at 15:59. This installation method works as well too; simply relocate the transmitter. Since it is low-pressure saturated steam, a condensation tank is not necessary. The horizontal section of the pressure tap pipe should have a slope, with the area indicated by the arrow being higher than the area ahead (this is where the condensate tank is installed), so that the column of condensate water remains at a constant height; any excess condensate water will flow away and will not accumulate in this horizontal section of the pipe. Otherwise, it affects the accuracy of the measurement.
This 20 kPa deviation cannot be ignored, and there are two ways to eliminate it: 1. Zero shift, which results in the pressure display on the transmitter not matching that on the DCS, but the value displayed as a percentage remains the same. 2. Zero adjustment. After filling the pressure guide tube with water, close the valve once, then unscrew the connector of the valve in order to zero the transmitter; Rosemount uses the option \"ZERO Trim\" for this purpose, while EJA uses \"ZERO ADJ\"
It is actually feasible to omit the condensation tank, as the medium does not flow and will condense naturally； The errors caused by the liquid column are also acceptable; you need to know what the process is concerned about and how the operating point is determined ； Of course, eliminating errors is the best approach, as described on floor 3.
This flow meter also has temperature and pressure compensation; could that have an impact on the flow rate as well? We haven’t used it in actual driving yet; it would be easier to discuss things if we were already using it, as long as the operator is aware of what to do. But with temperature and pressure compensation, it’s unclear just how much impact this will have on the flow rate It is well known that flow meters with temperature and pressure compensation are very important in industrial processes. The extent to which these meters affect the flow rate can only be determined by the calculation methods used within the module; such calculations are quite complex. Those working in the production process are not aware of the magnitude of this error, and moreover, it is an online value that keeps changing constantly.
The impact is negligible; we’re not selling steam anyway.
The impact is negligible; we’re not selling steam anyway.
But here, we have to pay for the steam; I really care about that