Requirements for turbine flowmeter piping

1. In order to eliminate the influence of uneven velocity distribution in the cross section of the pipeline on the measurement accuracy, the flow sensor should have a certain straight pipe section upstream and downstream, or install a rectifier to replace part of the straight pipe section. Generally, the upstream straight pipe section is not less than 15D, and the downstream straight pipe section is not less than 5D (D is the nominal diameter of the flow sensor).
2. In order to eliminate the influence of backflow, uneven velocity distribution and swirl, a rectifier can be installed upstream. At this time, the straight pipe length L of the upstream part of the flow sensor can be 10D. If it is 15~20D, the measurement accuracy can reach the calibration accuracy.
3. When the measured liquid contains solid impurities, a filter should be installed upstream of the flow sensor. The mesh number of the filter is 20~60 mesh (3~9 mesh/cm2). Generally, the mesh number of the flow sensor with a small diameter is more. The installation position of the filter should be considered to facilitate the disassembly and assembly of the filter.
4. When there is gas mixed in the liquid or when measuring easily gasified liquids, an air separator (degasser) should be installed.
5. If the measured liquid is easy to gasify, in order to prevent cavitation, the pressure at the outlet of the flow sensor should be higher than the value Pmin calculated by the following formula:
Pmin = 2△P   1.25Pv
Where: Pmin-minimum pressure; △P-pressure loss of the flow meter at the maximum flow rate;
Pv-saturated vapor pressure of the measured liquid at the highest operating temperature
6. If the flow through the flow sensor is too large, the bearing life will be too short. The flow is usually adjusted to an appropriate size through a valve, and the valve should be installed downstream of the flow meter.
7. In order not to interrupt the fluid delivery during maintenance, a stop valve is usually installed upstream and downstream of the flow sensor, and a bypass pipeline is set at the same time. It should be ensured that the bypass pipeline does not leak when the bypass valve is closed during measurement.
8. If reverse flow is likely to occur, a check valve should be added to prevent the fluid from flowing in the opposite direction.
9. The flow sensor should be concentric with the pipeline, and the sealing ring should not protrude into the pipeline.
10. In order to avoid gas accumulation in the flow meter, the flow meter should not be installed at the highest point of the horizontal pipeline.
11. If the flow meter is installed at the low point of the pipeline, a discharge valve should be installed on the pipeline to discharge sediment regularly.
12. The pipes before and after the flow sensor should be firmly supported so that there is no obvious vibration.
13. When cleaning the newly laid pipeline, a short pipe should be connected to the location where the flow sensor is installed, and then the flow sensor should be installed after the cleaning is completed.
14. When it is necessary to measure the temperature of the fluid, it should be measured at a length of 5 times the nominal diameter of the pipeline downstream of the flow sensor.