Pros and cons of common types of flow measurement technology.
07/30/2018
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