Pakarab fertilizers limited multan
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- Invasive primary device
- Rangeability
- 55 Field Instrumentation GEN Rev)
| Direct flow measurement: the volume of material that passes a certain location in a specified time interval. If an instrument directly measures the volume of fluid passing a certain location in a specified time interval, volume flow rate is measured directly. Indirect flow measurement: it provides instantaneous flow-rate values, but it does not measure accumulated volume. Instead, it measures changes in properties of flowing liquids changes in velocity, depth, or pressure. Indirect flow measurement requires both a primary and a secondary measuring device, A primary device interacts with the flowing fluid to produce a signal that is measured by the secondary measuring device. This measurement is then used as the indicated flow rate. Normally the function of the primary measuring device is to create a difference in pressure, or a pressure differential, in a flowing fluid liquid or gas. Invasive primary device: A device whose sensing elements come indirect contact with the fluid. Non-invasive primary device: A device whose sensing elements remain outside the wall of the pipe, never touching the flowing fluid. Ab secondary device measures or reads the differential to determine the flow velocity or volume flow rate of the fluid. Rangeability The rangeability of a flow meter is defined as Maximum flow rate / minimum flow rate This ratio tells the range of flow that a certain flow meter can effectively measure, from the lowest value to the highest value. Turndown Turndown is defined as Applied maximum flow rate / applied minimum flow rate Turndown is similar to rangeability, but turndown refers to the flow range of a flow meter in an installed system. The maximum flow rate in the application maybe well below the meter’s maximum limit. 55 Field Instrumentation GEN Rev) 3.2 Fluid flow measurement is accomplished by Download 3.37 Mb. Share with your friends:
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