Applications, Advantages and Disadvantages of Positive Displacement Flow Meters
Read: Positive displacement type flow meter
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
- Good accuracy
- Low maintenance, long life.
- It gives excellent accuracy and repeat-ability
- Accuracy not affected by the upstream conditions. It requires very little straight upstream piping.
- Suitable for high viscosity fluids
- Little sensitive to uneven flow distribution across the area of the pipe, it does not matter the flow is pulsing.
- Read out directly in volumetric units
- Good Turndown ratio
- Nutating Disc Flow Meter
- Oscillating Piston Flow Meter
Limitations of positive displacement meters
- In large pipe diameter PD flowmeters are heavier and expensive than the differential pressure type flow meters.
- 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.
- Sudden change in flow may damage the moving parts due to inertia.
- Periodic calibration is required for meter using in extreme conditions
- Moving parts subjected to wear and construction material susceptible to corrosion
- Not suitable for sticky, abrasive liquids.
- It may cause pulsation in flow