Are straight pipe sections required before and after the rotameter?
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This post was last edited by ljy3033 on 2017-4-19 at 15:25. It might be a clichéd question, but it is indeed one that remains subject to debate. I just saw a post discussing topics related to rotameters, which inevitably brought up the issue of straight pipe sections again. http://bbs.hcbbs.com/thread-1770385-1-1.html From a design perspective, when the instrumentation team specifies the installation requirements for rotameters to the installation team, it usually requires a certain straight pipe section (for example, 5DN ahead and 250 mm behind). I asked the instrument designers, and they said that the instrument installation specifications do not require straight pipe sections. However, it is better to have straight sections in the sample and during use, as this serves a streamlining purpose. I checked the \"Manual for the Installation Design of Process Piping in Petrochemical Plants\" (5th edition), and page P415 indeed specifies requirements for installing straight pipe sections. But Hai Chuan previously posted a thread discussing this issue as well; I didn’t write down the address, but I did note one sentence from it: “Rotary flow meters have no strict requirement regarding the length of the straight pipe section upstream of them, although some manufacturers require a length of (2–5)D – however, this is not really necessary.” ” I viewed the product descriptions of two rotameter manufacturers online, and indeed those descriptions did not mention anything about installation straight sections. So, what exactly is this straight pipe section like? Please share your opinions. **************** Another issue is that rotor flowmeters are generally installed in vertical pipelines, but they can also be installed in horizontal pipelines. I asked the instrument designers why it wasn’t chosen, and they said that there were widespread complaints about its poor performance, which is why it’s generally not selected. Has anyone used it? Please share your experience with its actual performance
Installed on vertical pipes, there is usually a certain length of straight pipe section; maintenance and inspection requirements must be taken into account during actual installation.
Control valves, flow meters, and other instruments all require straight pipe sections; this topic has been discussed many times. During pipeline installation, pipeline installers also add straight pipe sections. Vertical installation ensures that the material completely fills the pipeline
Is the professional term “vertical”? I think “upright” is more appropriate. If a rotameter is connected directly behind a control valve without a straight pipe section for buffering, and given that the diameter of the control valve creates a reduction in the pipe diameter, the flow velocity of the fluid passing through the valve core is higher than that in the rest of the pipe. There are also gaps around the fluid, and such unstable flow conditions can lead to inaccurate measurements by the rotameter. The one installed horizontally below likely has a U-shaped pipe inside the flow meter, which causes the fluid to move upward and then downward; as a result, its pressure drop and accuracy are not as good as those of a vertically installed unit. The advantage is that it can also be installed on horizontal pipes; those with the necessary conditions for piping do not choose this type
A straight pipe section is required for accurate measurement. A horizontally installed rotameter has a vertical pipe section inside, and inaccurate measurements are likely due to an insufficient straight pipe section.