Laminar Flow and Digital Flowmeters: An Explanation On How To Achieve Laminar Flow

When I see turbulent flow vs. laminar flow I vaguely remember my fluid dynamics class at the University of Cincinnati.  A lot of times when one thinks about the flow of a liquid or compressed gas within a pipe they want to believe that it is always going to be laminar flow. This, however, is not true and there is quite a bit of science that goes into this.  Rather than me start with Reynolds number and go through flow within pipes I have found this amazing video from a Mechanical Engineering Professor in California. Luckily for us, they bookmarked some of the major sections. Watch from around the 12:00 mark until around the 20:00 mark. This is the good stuff.

The difference between entrance flow, turbulent flow and laminar flow is shown ideally at around the 20:00 mark.  This length of piping that is required in order to achieve laminar flow is one of the main reasons our Digital Flowmeters are required to be installed within a rigid straight section of pipe that has no fittings or bends for 30 diameters in length of the pipe upstream with 5 diameters of pipe in length downstream.

This is so the meter is able to measure the flow of compressed air at the most accurate location due to the fully developed laminar flow. As long as the pipe is straight and does not change diameter, temperature, or have fittings within it then the mass, velocity, Q value all stay the same.  The only variable that will change is the pressure over the length of the pipe when it is given a considerable length.

Another great visualization of laminar vs. turbulent flow, check out this great video.


If you would like to discuss the laminar and turbulent flow please contact an Application Engineer.

Brian Farno
Application Engineer

1 -Fluid Mechanics: Viscous Flow in Pipes, Laminar Pipe Flow Characteristics (16 of 34) – CPPMechEngTutorials –

2 – Why Laminar Flow is AWESOME – Smarter Every Day 208 – SmarterEveryDay –



Video Blog: Compressed Air Sensor/Solenoid Control for Maximum Efficiency

The Electronic Flow Control, or EFC, is an EXAIR Optimization product to reduce air consumption in your facility.  Saving this electricity that is used to make compressed air will save you money and will help you to “Go Green”.  The EFC has 8 different modes that uses a timing sequence with a Photoelectric Sensor to turn on/off a solenoid valve.  In this video, I will go through each mode to demonstrate how the Electronic Flow Control will perform.

John Ball
Application Engineer

Twitter: @EXAIR_jb