What is a positive displacement flow meter?

Positive displacement (PD) flow meters are flow meters with high accuracy (in some cases ±0.1% of actual flow) and good repeatability (up to 0.05% of readings). These meters do not require power supply and do not require direct upstream or downstream piping installation. They are ideal for flow measurement of viscous fluids such as oils, fuels and solvents, which are difficult to measure with other types of flow meters.

PD flow meters are most widely used in household water meters, producing millions of units per year. Positive displacement flow meters can be used for clean, hygienic and corrosive liquids such as water and food, as well as some gases. They are often most suitable when high accuracy is required at a reasonable price.