Orifice plate flow meter

There’s nothing else but cleaning the orifice plate grooves and the sampling tube. It’s best to remove and clean it, but replacing the gaskets on large-diameter components is rather difficult. It’s best to try using an external backflow sampling tube.

For the flow orifice plate, it is mainly necessary to clean the annular channel of the orifice plate; currently, an attempt is being made to perform backflow cleaning using the external instrument tube.

First, it is necessary to verify whether the actual operating conditions match the design parameters of the orifice plate; thereafter, the orifice plate should be calibrated.

It might be that the wrong type of flow meter was selected; for heavy oil, wedge or paddle type meters are generally used, while orifice plates are used for light oil

Since the problem description is not clear, it’s difficult to make a judgment. It is recommended to first check whether there are any significant differences between the parameters in the design calculations for the orifice plate and those provided by you. If the calculations are correct and the orifice plate can be removed easily, then its opening dimensions can be measured. (I’ve encountered many cases where the orifice plates were installed in the wrong position; if that’s the case, then another gauge with a different tag number should also not be working properly.) I see that the medium you are testing is residue oil, which is a highly viscous and dirty medium; therefore, orifice plates are likely not suitable for use. If the indicated flow rate is higher than the actual one, it may be due to a blockage in the pressure measurement tube downstream, resulting in an illusion of a high differential pressure. Providing more information might make it easier to find out the truth.

It’s very likely a density issue; the provided density value must be accurate. Parameters such as differential pressure are also crucial, so verify the process conditions with the process engineers

You must have introduced purging gas into the pressure tap tube of your orifice plate

Does residue contain impurities? Clogged pressure tap tube? Is it also thermal and pressure compensation? Is the range setting appropriate?

There are many factors involved; was it used properly from the start? If it works fine during the initial installation phase, there might be one of the following two problems: a. Clogging in the pipelines b. Issues with the differential pressure transmitter