Which standards should be referred to for the straight sections before and after the flow meter?
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I just know that generally, it is withdrawn in 10D periods at the beginning and 5D periods afterward; but what specifications should be referred to for specific flow meters? I saw it on a forum; Appendix A can be found at the end of the \"Control Instrument Design Manual\", but it seems that the book \"Control Instrument Design Manual\" itself doesn’t exist.
This post was last edited by cwq84 on 2011-6-30 at 16:24. Generally, it’s best to follow the manufacturer’s samples; for a general idea, you can check the design manual at http://bbs.hcbbs.com/thread-830830-1-2.html. The manual is available here
The poster doesn’t necessarily have to follow the specifications; nowadays, the installation methods are based on the instructions provided with the flow meter, and those instructions already address the issue of straight pipe sections before and after it!
Generally, if there are specific requirements stated in the instrument’s calculation sheet or manual, the installation should be carried out in accordance with the manufacturer’s specific instructions. If there are no specific requirements, follow the instructions in the manual for installation.
First, follow the requirements in the instructions or refer to the \"GB 50093 2002 Code for Construction and Acceptance of Automation Instrumentation Projects\", whose appendix contains
This issue remains quite complex at present. During the design phase, meter manufacturers usually don’t determine the exact requirements, so a provision of ten units in the front and five units at the back is made. Once work starts and procurement begins, it turns out that the quantity specified is usually not sufficient. In the end, there’s nothing that can be done – the process engineers say the pipes cannot be modified, so that’s how it has to be done. . Each manufacturer gets different calculation results. . Some write ‘first 3, last 5’ on the sample, but in reality it’s not at all like that in the calculation sheet. In the end, they even say to you, “There’s no rule saying one has to be in the top ten or bottom five; this is just the way I do things. It’s necessary to use a large distance in order to get accurate measurements, and it doesn’t violate any rules.” And you can’t even get angry at that.
Specifications or manuals only state the principle-based requirements; different manufacturers have varying requirements for the straight pipe sections of flow meters. Install in accordance with the requirements for straight sections specified in the manufacturer’s instructions.
Follow the manufacturer’s requirements; 10 in the front and 5 at the back will generally suffice.
It is specified in the instrument selection and design guidelines, and it can also be found in the Chemical Process Automation Design Manual