Selection of sewage flow meter
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Hello, everyone! There are many parameters to consider when selecting a wastewater flow meter – how to determine them? For example: how are parameters such as density, viscosity, allowable pressure loss, and calibration range determined? Thank you again to all the experts!
Density, viscosity, temperature, pressure, etc., are the parameters of the medium being measured； The allowable pressure loss is the pressure drop caused by the flow meter that your process system can tolerate; it can be calculated by the manufacturer and then confirmed by you if no specific requirement exists ； The normal flow rate and maximum flow rate of the medium to be tested must be provided to the manufacturer, while the measurement range can be suggested by the manufacturer.
It’s a process modification requirement related to instrumentation; I work in the process area and there’s nothing I can do since several parameters cannot be determined. I hope experts out there can offer some guidance!
How are viscosity, pressure loss, and range determined?
Do you want someone to provide you with these data? You must have measured the viscosity, right? For the verification range, what is required for the instrument is its measurement range; the maximum process flow rate plus around 15% to 20% will suffice. If orifice plates or nozzle-type flow meters are used, it is possible to specify the pressure difference; is the pressure loss you mentioned referring to this situation?
How to calculate viscosity and pressure loss? The verification range is the measurement range plus 15-20% – I’ve never heard of that before! I beg!
Use the actual data you have measured for viscosity. If it has not been measured, inform the flow meter manufacturer of the components of the wastewater so that they can find a similar value. The allowable pressure loss refers to the maximum pressure difference that is permitted for this flow meter. For example, if the pressure before the flow meter is 0.6 MPa (G), and the process system downstream of the flow meter requires a pressure of no less than 0.55 MPa (G), then the allowable pressure loss is less than 0.05 MPa (G). As for the calibration range, I’m not sure what the exact wording is in your instruments’ specifications Your understanding just now was incorrect; it’s not the measurement range that is increased by 15~20%, but rather the maximum flow rate
The allowable pressure loss should be calculated, right? There must be a calculation formula for it
If it is a complex process system, process calculations or assessments should be carried out to determine what the minimum system pressure required by the subsequent process systems is. I’m not sure whether your process is complex Under normal circumstances, the following method can be used: if vortex flow meters or electromagnetic flow meters are chosen, the actual pressure loss is very small and can be ignored. If you choose orifice plates or nozzle-type flow meters, you should aim for the smallest possible size, with you making the final decision. Of course, it can’t be too small; if it is, the flow meter cannot be selected.
The pipeline layout is simple; what is the acceptable range for pressure loss? There is a calculation formula: 1.2 * medium density * square of medium flow velocity. Is such a formula available?