Pros and cons of common types of flow measurement technology.

Learn about the strengths and liabilities of different types of flow meters. Information courtesy of previous Pumps & Systems articles, primarily by Badger Meter and Ray Hardee

Differential Pressure
Pros

  • well understood
  • no moving parts
  • not greatly affected by viscosity changes

Cons

  • limited accuracy and turndown
  • complex installation requirements

Coriolis
Pros

  • handles viscous or difficult fluids that don’t work well with other measurement technologies
  • no internal moving parts
  • minimum upkeep once installed

Cons

  • expense
  • sometimes considered too sophisticated

Electromagnetic
Pros

  • no moving parts
  • low pressure drop
  • high accuracy
  • can handle range of viscosity, temperature and pressure

Cons

  • tendency to foul
  • heavy weight
  • expense

Positive Displacement (PD)
Pros

  • highly accurate
  • easy to maintain
  • does not require straight pipe lengths

Cons

  • only clean fluids
  • large size
  • difficult to install

Thermal Mass
Pros

  • low purchase cost
  • works well with gases

Cons

  • low to medium accuracy

Turbine
Pros

  • high accuracy
  • wide turndown
  • repeatable measurements

Cons

  • only clean fluids
  • requires recalibration and service

Impeller
Pros

  • universal mounting
  • relatively low cost

Cons

  • only clean, low-viscosity fluids
  • requires higher fluid velocity

Ultrasonic
Pros

  • can be used with corrosive fluids or gases
  • unaffected by changes in temperature, viscosity, density or pressure

Cons

  • much less dependable at low flow rates
  • sensitive to unknown piping variables

Variable Area
Pros

  • simple
  • inexpensive
  • reliable

Cons

  • must be mounted perfectly vertical
  • needs to be calibrated
  • relatively low accuracy

Vortex
Pros

  • no moving parts
  • no regular maintenance

Cons

  • only clean liquids
  • may introduce pressure drop