Regarding the selection of flow meters: different operating conditions, different media
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Taking on a project in practice: There is a newly built wastewater treatment plant in an industrial park, with a processing capacity of around 400 tons per day. Currently, there are more than 10 small factories located near this wastewater treatment plant, and the number is expected to rise to over 50 in the future. Since fees have to be imposed on these polluting enterprises for waste treatment, it is necessary to monitor the flow rate in each discharge pipeline. The monitoring system itself is straightforward to implement; the difficulty lies in selecting the appropriate flow meters. The reasons are as follows: 1. The majority of these devices are buried underground. Although flow wells can be added, they remain underground, so factors such as humidity and resistance to freezing (given the temperatures in the northeast) must be taken into account, as well as the required protection level to prevent flooding ； 2. The content of wastewater varies, with a wide range of possibilities ； 3. The flow rate varies; it is all gravity-driven flow. Some companies drain water regularly, while others may have a low flow rate and operate in a semi-closed state for extended periods, or the pipes might remain empty at all times – any of these scenarios is possible. 4. The material of the pipes varies as well; it is presumed that there are hardly any cement pipes, with most being metal pipes, pipes with metal linings, non-metallic pipes such as PPR, fiberglass pipes, and so on ； All prefer external measurement methods, that is: without modifying the existing pipelines, which avoids various complications. 5. The maximum pipe diameter shall not exceed DN150, and the maximum flow rate can only be estimated using a constant based on the previous daily processing volume. Certain enterprises will certainly experience peak drainage volumes, as there are various types of wastewater involved, and in all cases flow does not occur at full pipe capacity. Attempting to create concave shapes in the pipes to ensure full flow can instead lead to pipe blockages, so this approach is not considered. For other requirements, I would appreciate it if experienced colleagues could recommend instrument brands or types of measurement. If it’s not convenient to mention the manufacturer’s name directly, you can send me a PM. Thank you all
You can install an ultrasonic open-channel flow meter
The flow meters produced by our company can fully meet your needs, but you need to leave your contact information so that my engineer can get in touch with you.
I’ve checked your company’s website, and based on my personal experience, none of the options suit my working conditions. I also thank you for leaving me 4 messages, but don’t just say it’s good – I want to know which of your products is good and why. I work in system integration; first and foremost, technical feasibility is important, and at the very least, there should be terms that interest me. Your guarantee at this early stage is merely a business practice; it’s too early for my project.
In my opinion, it is possible to consider using an Anubaa flow meter or a compact orifice plate flow meter; however, it would be best to have a water well available
It seems that installing a flow well is necessary； Furthermore, virtually all methods of flow measurement require the installation of equipment on the existing pipes, including open-channel flow meters; it therefore seems that the pipes will have to be modified as well. Another question: I’m considering using a Roots flow meter, also known as a rotary vane flow meter. My main concern is particle impurities; in any case, it will be necessary to modify the pipes and install a flow measurement well. Adding a pipe filter might not be a big issue. What’s confusing is what pressure difference is required to drive a Roots flow meter; I hope it isn’t too large. After all, Roots flow meters are relatively inexpensive, although they may require some maintenance over time. Users are receptive, and it’s easy to launch the project. So the preliminary plan is to mainly use ultrasonic open-channel flow meters and Roots flow meters. Similar to the Pitot tube, I’m afraid that when flow is at half pipe velocity, it isn’t sufficient to submerge all of the dynamic and static pressure sampling ports ； I’m also worried about this with orifice plates. No pressure difference can be generated in the semi-pipe flow state— furthermore, for orifice plates and nozzles, the range ratio is usually 1:3, meaning they can hardly be used when the flow rate is less than 30% of the full scale. This post was last edited by Icetide on 2009-4-11 17:47]
The simplest way is to use electromagnetic methods; the pipeline needs to be modified slightly, through full pipe flow or pressurization, etc. So as I said, let my engineer talk to you and you’ll understand
I also considered electromagnetic flowmeters, but measures such as using concave tubes are needed to ensure full-flow conditions; for various types of wastewater, some of these pipelines may get blocked by debris, sediment, and other substances.