# Flow Measurement definition and its type

Updated: Nov 10, 2020

In this article, you will learn the definition of a term used in flow measurement and type of flow measurement technique. To know the history of the Flow measurement click here.

Flow measurement plays an important role from calculating mass flow to volumetric flow which are a critical and important parameter to know about actual total flow generated. flow can be measured for liquid or gas. both can be measured in mass flow or volumetric flow.

In both case material related bases on flowing fluid's density. however, in the case of liquid it is totally independent of density and in case of gas density mostly depend upon temperature and pressure.

Let discuss the difference between mass flow and volumetric flow with the help of the definition,

Mass Flow - Mass flow rate is a mass of fluid which passes per unit of time. mass flow measured in kg/s or kg/h represented by symbol m.

Volumetric Flow - volumetric flow is a volume of fluid which passes per unit of time. volumetric flow measured in m3/s or m3/hr denoted by Q.

### Effect on measurement due to different measuring condition,

Gas service - Gases is compressible and change its volume due to different pressure and temperature.

So volume at one temperature and pressure can never be the same at different temperature. in case of actual flow rate measured through the meter and standard flow rate can be measured through meter using a unit like an actual cubic meter per hour or standard cubic meter per hour. Mass of gas can directly measure independent of temperature and pressure using different flow measuring technique.

Liquid service - Gases are compressible and change it's over which can be measured in variety unit out them most commonly used unit is a gallon per min.

### Types of Flow Measurement Method

there are various method to measure flow based on the condition we can use an appropriate method which can give the best result. methods are,

1) Mechanical Flow Meter

1. Turbine Flow Meter

2. Oval gear meter

4. Current meter

2) Obstruction Based Meter

1. Orifice plate

2. Venturi tube

3. Wedge type

4. Annubar

5. Pitot tube

6. Flow nozzle

3) Variable Area Flow Meter

1. Rotameter

4) Thermal Mass Meter

5) Ultrasonic Flow Meter

6) Electromagnetic Flow Meter

7) Vortex Flow Meter

8) Coriolis Mass Flow Meter

9) Laser Doppler Flow Meter

10) Sonar Flow Meter

11) Open Channel Flow Meter