Difference between Differential Pressure Flow Meter and Positive Displacement Flow Meter
Differential pressure (DP) flow meter and positive displacement (PD) flowmeters are two type of flow rate measuring device. They are worked on a different principle.
To know more about these flow meter, please read.
- Differential Pressure Flow Meter Working
- Positive Displacement Type Flow Meter
Here is the quick comparison between DP flow meter and PD flow meter
Differential Pressure Flow Meter
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Positive Displacement Flow Meter
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The indirect method of measurement. To find flow rate they use Bernoulli’s
principle of conservation energy
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Flow rate measured directly in volumetric unit
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There is no need of mechanical movement of component (no moving
parts). Differential pressure head typically measured by using pitot tubes,
manometer.
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There is a mechanical movement of component of measuring device.
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Measure pressure drop across a restriction in passage of fluid
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Entrap and release fixed amount sample fluid
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Used for low viscous fluid
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Used for high viscous fluid, less accurate in low viscous fluid
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It cannot use for low flow rate
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It can measure low flow rate
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Need long straight pipe in upstream and downstream to accurate
measurement
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No need of long straight pipe in upstream and downstream.
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High sensitive to uneven flow(pulsing)
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Little sensitive to pulsing
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Low turndown ratio
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High turndown ratio
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Venturi meter,Orifice meter, Dall tube etc
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