Can the orifice plate be enlarged and the measuring range changed?
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The flow rate measured by the orifice plate is not accurate. It is suspected that the parameters are wrong. Can it be modified by expanding the hole?
What does not allowed mean? Is it instability or systematic error? Can you elaborate on the situation? There are many reasons for inaccurate measurement. The installation location may be unqualified, or there may be a problem with the pressure pipe, or the media properties may be incorrectly calculated. It's better to rule out other problems first. Moreover, if it is a systematic deviation, the reproducibility of your own calibration results is better. You can recalibrate without using the expansion plate and change the range of the differential pressure transmitter. Generally, large factories have a place to calibrate orifice plates. If it is convenient, you can give them to them for calibration. But don't expect the orifice plate flowmeter to be very accurate. It only measures a general trend to see the trend.
You can back-calculate the differential pressure based on the orifice plate diameter and flow range, and then reset the range of the differential pressure transmitter.
Don't do any reaming! This is a serious destructive matter. It is easy to expand and it is too late to regret it. As for changing the measurement range, it is still possible, but you must calculate it carefully and don't make mistakes.
There is no need to expand the hole. Generally, the orifice plate has a margin when processing, and the range increases within a certain range. You can calculate the corresponding differential pressure value based on the maximum flow rate and maximum differential pressure on the calculation book, and then calculate the corresponding differential pressure value with the maximum flow value you need. Just change the differential pressure range of the differential pressure transmitter again. The range of the DCS end should also be changed to the later maximum flow value. If the required maximum flow rate is much higher than the original design, you need to consult the manufacturer to see if it supports it. The accuracy of the orifice plate is still relatively high within a certain range. If the measurement range is exceeded too much, the accuracy will naturally decrease. If the deviation is too large, the measured data will be meaningless.