Applications, Advantages and Disadvantages of Positive Displacement Flow Meters

Applications of positive displacement meters

• They are used in high viscous, dirty fluid which does not flow through the straight conduit.
• Hydraulic testing, Chemical injection or chemical dosing, pharmaceutical application and similar precision applications.
• Custody transfer of gasoline fuels.
• Residential water, or gas metering.
• Oil hydraulics
• It can use to measure the high viscous dirty fluid. However, it is advised to use in clean, noncorrosive, and non-erosive fluid for measurement accuracy and longevity.

Advantages of positive displacement meters

1. Good accuracy
2. Low maintenance, long life.
3. It gives excellent accuracy and repeat-ability
4. Accuracy not affected by the upstream conditions. It requires very little straight upstream piping.
5. Suitable for high viscosity fluids
6. Little sensitive to uneven flow distribution across the area of the pipe, it does not matter the flow is pulsing.
7. Read out directly in volumetric units
8. Good Turndown ratio

Limitations of positive displacement meters

1. In large pipe diameter PD flowmeters are heavier and expensive than the differential pressure type flow meters.
2. They are normally limited to higher viscosity fluid - with very low viscosity liquid or in gas this meter is less accurate because there is more leakage in the internal sealing surface.
3. Sudden change in flow may damage the moving parts due to inertia.
4. Periodic calibration is required for meter using in extreme conditions
5. Moving parts subjected to wear and construction material susceptible to corrosion
6. Not suitable for sticky, abrasive liquids.
7. It may cause pulsation in flow