A positive displacement flow meter is a type of flow meter that requires fluid to mechanically displace components in the meter in order for flow measurement.
Sino-Inst offers a variety of flow meter sensors for industrial level measurement. If you have any questions, please contact our sales engineers.
What is a Positive Displacement Flow Meter
A positive displacement flow meter is a fixed small volume is used to repeatedly measure the volume of fluid passing through the flowmeter. The “metering space” of a positive displacement flow meter is a space that constitutes a standard volume inside it. This space is formed by the inner wall of the meter housing and the rotating parts of the flowmeter.
How Does a Positive Displacement Flow Meter Work
When the fluid passes through the flow meter, the pressure difference will be generated between the inlet and outlet of the flow meter. This pressure difference causes the rotating parts of the flowmeter to rotate and discharge the fluid from the inlet to the outlet. In this process, the fluid fills the “metering space” of the flowmeter again and again, and then is continuously sent to the outlet. Under the conditions of a given flow meter, the volume of the measuring space is determined, as long as the number of rotations of the rotor is measured. The cumulative value of the volume of fluid passing through the flowmeter can be obtained.
Advantages of Volumetric Flow Meters
- High measurement accuracy.The high precision of the internal components means keeping the gap between the sealing surfaces to a minimum. The smaller these gaps, the higher the accuracy.
- The installation pipeline conditions have no influence on the measurement accuracy and can be used for the measurement of high-viscosity liquids.
- It can be used for the measurement of high viscosity liquids.
- Wide range.
- The direct-reading instrument does not require external energy to directly obtain the accumulated, total, clear and simple operation.
Use and Maintenance
- The volumetric flowmeter should be installed and used in accordance with the standard flow range, nominal pressure and flow direction marks on the nameplate.
- The positive displacement flowmeter should work under the condition that the fluid temperature is -20~+120℃ and the ambient temperature is -20~+55℃ and the relative humidity of the environment is not more than 80%.
- When the positive displacement flowmeter leaves the factory, it is calibrated with water at room temperature. If the measured fluid is different from the water at room temperature,the constant should be corrected or re-calibrated with the actual measured fluid, but for fluids with a viscosity less than 5×10-6m2/s (5Mpa.s), there is no need to re-calibrate.
- Under normal circumstances, the service life of positive displacement flowmeters is generally from six months to one year, depending on the severity of the working conditions. And should be removed and washed regularly. If the shaft or bearing is found to be severely worn, it should be replaced and re-calibrated.
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