HomeBasicIndustrial Flow Measurement | A Complete Beginner Guide

Industrial Flow Measurement | A Complete Beginner Guide

Flow measurement is very important in the industry. In this article, I want to share with you all one guide that helps you to learn about Industrial Flow Measurement.


There are multiple technologies available for the measurement of Flow. in this Artic I am covering all the basics of Industrial Flow Measurement and the Best Useful free resources.

Before we start learning about flow measurement, we have to learn about the terms below because it is very important.

  • Accuracy
  • Repeatability / Precision
  • Rangeability / Turn Down Ratio

We one by one learn about these terms in simple language and examples for a better understanding of these terms.

1. Accuracy

Accuracy is a very commonly used term in any instrument. As per definition, Accuracy shows the closeness of the measured value to the actual true value.

If the Measured value is close to the actual then the instrument is accurate. And if the Measured value is far from the actual value, then we conclude that the instrument is less accurate.

2. Repeatability / Reproducibility

Repeatability and Reproducibility are two aspects of Precision. In simple language Repeatability / Precision is defined as the Closeness of Measured to each other.

When we take repeat measurements in the same location with the same physical conditions then it is called Repeatability of Instruments.

Reproducibility is defined as repeat measurements with different locations with different physical conditions. You can visually that what is the difference between Accuracy and Precision.

3. Rangeability / Turndown Ratio

Rangeability or Turndown Ration is very important in flow measurement. In simple Language, Rangeability is defined as a Range of Flow that is measured within an accuracy tolerance. Rangeability is also represented in the “Turndown ration“.

Turndown ratio is defined as the ratio of Maximum flow and Min flow that the flow meter can measure.

Example: – A meter is Measure the Maximum flow of 100m3/d (100%) and the minimum flow of 10m3/d (Within specific accuracy tolerance like 0.5%) has 10:1 Rangeability or turndown.

STEP 1. Turndown Ratio = Maximum flow/ Minimum flow

STEP 2. Turndown Ratio = 100/10

STEM 3. Turndown Ratio = 10: 1

It shows that the meter measures the flow rate from 10m3/d to 100m3/d with 0.5% accuracy.

The meter may also provide better accuracy in a reduced measuring range if the meter provides 0.5% accuracy for 10:1 Turndown. It may also provide a tighter tolerance of 0.25% for a 3:1 turndown ratio.

I think now you have an idea about the basic terminology that you need to understand in flow measurement.

Types of Flow Measurement Technology

There are multiple flow measurement technologies available. And all technology has its advantages and disadvantages.

Closed Pipe Flow MeasurementVelocity/ ForceTurbine
CE and ME
Positive DisplacementNutating disk
Oval Gear
Rotating Piston
Rotating Vane
InferentialVariable Area Rotameter
V Cone
Open ChannelParshall Flume
Type of Flow Measurement Technology

Standards in Flow Measurement

Many organizations specially made worldwide acceptable standards for flow measurement.

Because Measurement of accurate flow is directly or indirectly connected with money. for example, oil and gas if it is not measured accurately then it shows a direct effect on the money factor.

1. American Gas Association (AGA)

Sr. No.StandardsDetails
1AGA Report No. 3Orifice Metering of Natural Gas
2AGA Report No. 7Measurement of Gas by Turbine Meters
3AGA Report No. 8Compressibility and Super-compressibility for Natural Gas and other Hydrocarbons.
4AGA Report No. 9
Measurement of Gas by Multipath Ultrasonic Meters
American Gas Association (AGA) Standard

2. American Petroleum Institute (API)

Sr. No.StandardsDetails
1Chapter 18Custody Transfer
2Chapter 19Evaporation Loss Measurement
3Chapter 20Allocation of Measurement of Oil and Natural Gas.
4Chapter 21Flow Measurement Using Electronic Metering Systems
5API RP 551 Process Measurement Instrumentation
6API 1101Measurement of Petroleum Liquid Hydrocarbons by Positive Displacement Meter
7API 2534Measurement of Liquid Hydrocarbons by Turbine Meter Systems
API Manual of Petroleum Measurement Standards – Measurement of Crude Oil by Coriolis Meter
American Petroleum Institute (API) Standards

3. American Society of Mechanical Engineers (ASME)

Sr. No.StandardsDetails
1MFC-IMGlossary of Terms Used in The Measurement of Fluid
Flow in Pipes
2MFC-2MMeasurement Uncertainty for Fluid Flow in Closed
3MFC-3MMeasurement of Fluid Flow in Pipes Using
Orifice, Nozzle, and Venturi
4MFC-4MMeasurement of Gas Flow by Turbine Meters
5MFC-5MMeasurement of Liquid Flow in Closed Conduits
Using Transit-Time Ultrasonic Flowmeters
6MFC-6MMeasurement of Fluid Flow in Pipes Using Vortex Flow
7MFC-7MMeasurement of Gas Flow by Means of Critical
Flow Venturi Nozzles
8MFC-8MFluid Flow in Closed Conduits-Connections for Pressure
Signal Transmissions Between Primary and Secondary Devices.
9MFC-9MMeasurement of Liquid Flow in Closed Conduits by
Weighing Method.
American Society of Mechanical Engineers (ASME)

4. American Society for Testing and Materials (ASTM)

Sr. No.StandardsDetails
1D1070-85Standard Test Methods for Relative Density of Gaseous
2D1072-90Standard Test Method for Total Sulfur in Fuel Gases
3D1142-95Standard Test Method for Water Vapor Content of Gaseous
Fuels by Measurement of Dew-Point Temperature
4D1826-94Standard Test Method for Calorific (Heating) Value of
Gases in Natural Gas by Continuous Recording Calorimeter
5D1945-96Standard Test Method for Analysis of Natural Gas by Gas
American Society for Testing and Materials (ASTM) Standard

Learning Resources

1. Visual Learning through Video

I would like to thank the Endress+Hauser team for providing such amazing content on flow measurement.

1. Coriolis Flow Meter

The Coriolis Flow Measurement

2. Magnetic Flow Meter

The Magnetic Flow Measurement

3. Ultrasonic Flow Meter

The Ultrasonic Flow Measurement

4. Vortex Flow Meter

The Vortex Flow Measurement

5. Thermal Mass Flow Meter

The Thermal Mass Flowmeter

6. DP Flow Meter

The Differential Flowmeter using Orifice

7. DP Flow Meter Using Pitot Tube

DP Flow Meter Using Pitot Tube

2. Free Reference Books

ABB provides a free Handbook for Industrial Flow Measurement and you can download this free Handbook by clicking the download button.

Free Handbook by ABB


I hope now you have a basic understanding of industrial flow Measurement and that all the resources I shared become helpful to you.

If you like this article you can also like my previous article on Magnetics flowmeter | A complete Guide.

Instrumentation and Control Engineer | IAS Member

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