Positive Displacement Flow Meter Principle

Positive displacement (PD) meters are the types of flowmeters which are suitable for measurement of viscous liquid flows. These are also considered ideal for applications which require use of a simple mechanical meter
system. In general, a positive displacement flowmeter consists of a chamber or cavity which restricts the flow.

A rotating or reciprocating mechanical device is located inside the chamber to generate fixed-volume discrete parcels from the flowing liquid. Via PD meter units, liquids get separated into exactly calculated increments which are then further counted by a connecting register. Since every measured increment represents a distinct volume, these types of meters are widely used for automatic batching and accounting purposes.