Question: Large fluctuations in Rosemount electromagnetic flowmeters
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As the title suggests: These days, the flow rate of the denitration urea flow meter is fluctuating greatly, ranging from 100 to 300 L/h, while the urea flow control valve is not moving; there are no changes in other processes.
There are three boilers in total; the other two are operating normally, while this one is showing significant changes
This post was last edited by hfrs on 2018-7-27 at 15:11. With the quality of construction and design standards you have, it’s strange if there are no problems.
1 The installation pipeline of the flowmeter should be 10D in length at the front and 5D at the back. 2 Check whether the pipeline is full, for any bubbles or two-phase flow. 3. Check whether there are crystals in the inner cylinder of the flow meter. That’s all I can help you with
For the Emerson 8700 series, the straight pipe section requires 5D at the front and 2D at the back; it is important to ensure measurement of the entire pipe length. Don’t assume that for every flow meter it’s \"10D in front and 5D behind\"; when using a standard orifice plate with a differential pressure transmitter, the selection depends on the orifice plate ratio as well as the configuration of the pipes upstream and downstream. For other types of flow meters, refer to the manufacturer’s instructions
Moreover, \"It is possible to use installations with reduced straight sections ranging from 0 to five pipe diameters. In such installations, the performance will drop by up to 0.5% of the rated value; however, the reported flow rates will remain highly repeatable.\" If the on-site conditions truly do not allow for a straight pipe section of 5D in length, then the accuracy will only decrease by 0.5%, while the repeatability of the measurements will still be excellent.
First: The electromagnetic flowmeter must be used with a full pipe. Secondly, check whether your flow meter meets the requirement of top 10 and bottom 5. Take another look to see if there is dirt on the insulating porcelain parts of the electromagnetic flowmeter; remove them and clean them. There should be no problem then
Installing it in this way can easily lead to the flow meter not being fully filled with fluid, resulting in bubbles and other issues that cause measurement fluctuations. If it was normal before but now there are large fluctuations, the most likely reasons are dirty electrodes, crystallization, or even issues with the electrode material due to corrosion by the substances in use; therefore, it’s advisable to remove them for inspection if possible.
Congratulations. Large fluctuations are great! Fighting against the heavens brings endless joy, fighting against the earth brings endless joy, and fighting against foreign powers brings endless joy – it’s absolutely thrilling! :In the heat of summer, I climb up the tank to adjust the clock; under the warm sun, tiny beads of sweat appear and then evaporate right away – it’s really cool and comfortable.
1. Is the opening degree of the control valve low? Try increasing the valve opening a bit; if things return to normal, it means the pipeline isn’t fully filled with fluid. 2. Check whether there is dirt covering the electrodes inside the chamber, as well as whether there is scaling or foreign objects in the pipeline. 3. Consider environmental interference – is there a strong magnetic field present? 4. Restart after powering off