What should be the appropriate setting for the flow measurement range?

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This post was last edited by wang_qia on 2023-9-27 at 20:14. How should the flow measurement range be set? When the water flow is above 3 meters per second, the accuracy is around 0.2%; when the water flow is below 3 meters per second, the accuracy decreases, but it remains above 1%, so it can be used with confidence. Experience gained at great risk: When setting the range for a flow meter to measure liquids, it is not based on the standard guideline that the maximum flow rate should not exceed 90% of the full scale – such a setting carries a high risk of overflow. The reason why flow meters often exceed their rated range is that centrifugal pumps are usually chosen to be large in capacity; they have strong pumping power. The maximum height of the pipelines is either 5 meters or 10 meters, and centrifugal pumps can eject water up to 30 meters high. The lower the overall resistance in the pipelines, the more liquid the centrifugal pump can pump out. This is the fundamental reason why flow meters exceed their rated range after the pump starts operating. There is another reason: in the workshop, nitrogen is often used to force liquids to be sprayed out. Instead of using pumps, high-pressure nitrogen is employed to empty storage tanks holding several hundred cubic meters in just a few minutes – 100 cubic meters in 15 minutes, which means an instantaneous flow rate of 400 cubic meters per hour. A DN250 diameter pipe can handle 400 cubic meters of flow; it’s insane. That’s how work is done in the workshop. No consideration is given to whether the instruments can measure such high flow rates; they just keep pushing hard, resulting in flow rates that exceed the instrument’s range. With a DN250 pipe, how can you measure a flow rate of 500 cubic meters if no appropriate settings are used? ! ! ! . DN10: 1 m3/h, DN15: 5 m3/h, DN25: 10 m3/h, DN32: 15 m3/h, DN50: 50 m3/h, DN65: 100 m3/h, DN80: 100 m3/h, DN100: 100 m3/h, DN125: 200 m3/h, DN150: 300 m3/h, DN200: 500 m3/h, DN250: 500 m3/h, DN300: 1000 m3/h. The flow rate range is related to the pipe diameter: when measuring liquid media, the flow rate range is connected to the pipe diameter. To facilitate memory, ensure accuracy, and prevent excessive flow in the processing area, the flow rate range can be set according to the following corresponding relationships. DN10 1m3/h DN15 5m3/h DN25 10m3/h DN32 15m3/h DN50 50m3/h DN65 100m3/h DN80 100m3/h DN100 100m3/h DN125 200m3/h DN150 300m3/h DN200 500m3/h DN250 500m3/h DN300 1000m3/h Automatic control instruments