Video Blog: How To Remove, or Move, A Digital Flowmeter By Using Block-off Rings

If you need to remove (or move) a Digital Flowmeter, EXAIR has Block-off Rings that are used to safely cover & seal the holes that were drilled in the pipe for installation. Here’s how they work:

If you’ve got any questions about Block-off Rings, Digital Flowmeters, or would like to find out more about EXAIR Corporation can help you get the most out of your compressed air system, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Fluid Mechanics – Boundary Layer

Fluid mechanics is the field that studies the properties of fluids in various states.  Fluid dynamics studies the forces on a liquid or a gas during motion.  Osborne Reynolds, an Irish innovator, popularized this dynamic with a dimensionless number, Re. This number determines the state in which the fluid is moving; laminar, transitional, or turbulent.  For compressed air, a value of Re < 2300 will indicate a laminar air flow while the value of Re > 4000 will be in the range of turbulent flow.  Equation 1 below shows the relationship between the inertial forces of the fluid as compared to the viscous forces.

Equation 1:

Re = V * Dh / u

Re – Reynolds Number (no dimensions)

V – Velocity (feet/sec or meters/sec)

Dh – hydraulic diameter (feet or meters)

u – Kinematic Viscosity (feet^2/sec or meter^2/sec)

To dive deeper into this, we can examine the boundary layer.  The boundary layer is the area that is near the surface of the object.  This could refer to a wing on an airplane or a blade in a turbine.  In this blog, I will target the boundary layer inside pipes, tubes, and hoses that are used to transport fluids.  The profile across the area (reference diagram below) is a velocity gradient.  The boundary layer is the distance from the wall or surface to 99% of the maximum velocity of the fluid stream.  At the surface, the velocity of the fluid is zero because the fluid is in a “no slip” condition.  As we move away from the wall, the velocity starts to increase.  The boundary layer thickness measures that area where the velocity is not uniform.  If you reach 99% of the maximum velocity very close to the wall of the pipe, the air flow is turbulent.  If the boundary layer reaches the radius of the pipe, then the velocity is fully developed, or laminar.  Mathematically, laminar flow equations can be calculated, but turbulent flows require theories and experimental data to determine. 

As an analogy, imagine an expressway as the velocity profile, and the on-ramp as the boundary layer.  If the on-ramp is long and smooth, a car can reach the speed of traffic and merge without disrupting the flow.  This would be considered Laminar Flow.  If the on-ramp is curved but short, the car has to merge into traffic at a much slower speed.  This will disrupt the flow of some of the traffic.  I would consider this as the transitional range.  Now imagine an on-ramp to be very short and perpendicular to the expressway. As the car goes to merge into traffic, it will cause chaos and accidents.  This is what I would consider to be turbulent flow.     

Hot Tap DFM

In a compressed air system, similar things happen within the piping scheme.  Valves, tees, elbows, pipe reducers, filters, etc. are common items that will disrupt the flow.  Let’s look at a scenario with the EXAIR Digital Flowmeters.  In the instruction manual, we require the flow meter to be placed 30 pipe diameters from any disruptions.  The reason is to get a laminar air flow for accurate flow measurements.  In order to get laminar flow, we need the boundary layer thickness to reach the radius of the pipe. 

Why is this important to know?  In many compressed air applications, the laminar region is the best flow to generate a strong force; efficiently and quietly.  Allowing the compressed air to have a more uniform boundary layer will optimize your compressed air system.  And for the Digital Flowmeter, it helps to measure the flow accurately and consistently.  If you would like to discuss further how to reduce “traffic jams” in your process, an EXAIR Application Engineer will be happy to help you.

John Ball
Application Engineer
Twitter: @EXAIR_jb

Photo: Smoke by SkitterphotoPixabay license

About Rotary Screw Air Compressors

What is an air compressor? In simple terms it is a machine that increases fluid pressure, it works by changing the volume of air and storing it in a storage tank. Many industries use compressors to increase production and thus has led to the development of many new industries. There are a couple types of air compressors but today I will focus on the Rotary Compressor.

The Rotary Screw Compressor is a very common type of air compressor. This compressor uses dual rotors with meshing lobes that trap air while rotating. The rotation continues to push air toward a discharge port while decreasing the space the air take sup, thus increasing pressure. The rotary compressor has a simple structure with few components and has some clear advantages over other compressors:

  • Longevity
  • When operating, they are quiet
  • Low vibration
  • Continuous operation, or they can match demand

Some disadvantages include:

  • Skilled maintenance required compared to other compressors.
  • They are more expensive than other compressors

There are two types of rotary air compressors. They are oil-injected and oil-free rotary air compressors. Oil-injected rotary screw compressors as the name suggests has oil injected in the compressor element during the air compression. An insignificant amount of oil will escape into the compressed air system also known as “oil carryover”. The use of EXAIRs oil removing filters and filter separators will help remove the oil, moisture and other particulates from the compressed air lines resulting in clean compressed air.

Oil-free rotary screw compressors are similar to the oil-injected compressor but without the use of oil. The oil-free compressors use a two stage system with a cooling process between stages as the compressed air will become extremely hot if not for a cooling process between stages of compression. The oil-free compressors are commonly used in food and medical industries.

EXAIR is here to help with your “Intelligent Compressed Air Products” so please contact us with your compressed air tooling needs.

Eric Kuhnash
Application Engineer
Twitter: @EXAIR_EK

File:IngersollRand R-series-R110.jpg image is licensed under the Creative Commons Attribution 3.0 License.

Methods, Patterns, and Continuous Improvement

I’ve blogged about the fact that I am married to an amazing woman and we have been blessed with three incredible daughters before. My wife and I are constantly being reminded of just how different raising kids in this digital and rapidly changing world is compared to when we were kids. And, just writing those statements makes me realize I have truly entered the next (I’m old) chapter of my life.

My oldest, who is 12, is at that point where she is gaining some independence at middle school, and at the same time is getting sucked into social norms where she can easily be consumed by social media and screen time. The challenge I took on was to find something analog that we could both pick up and enjoy, maybe even challenge each other with. Enter a classic that I was never able to master, and still can’t without the aid of another (my 12 year old), the Rubik’s Cube. I was honestly shocked when she took the time to review a video from our library and learned the patterns to solve the cube. Turns out a few of her friends are even able to solve them and thus the education began.

A traditional 3×3 Speed Cube in a solved state then converted to a checkerboard pattern.

What I once thought was an impossible task was broken down into patterns and a logical path to correct and straighten out the tangled squares. The are a number of methods to solve the standard 3×3 cube. No matter what, the pattern has to be recognized, implement the steps to solve, and then improve through repetition. Not many people pick something like this up, solve it once and then sit it down. It becomes a process of continuous improvement and that is exactly what my daughter took on. For me, it reminded me of Lean Manufacturing and every process I have ever looked at professionally. It was truly rejuvenating for me to see her take on the challenge and then have an urge to improve her process time.

When I came into work the next day, it clicked. That same process of methodical movements could all connect to our Six Steps to Compressed Air Optimization. Each of these steps is solving another layer of a mixed up cube. While at first, the process of optimizing a compressed air system can easily seem out of reach it is easily broken down into steps that result in a solution. Then, instead of taking all of that new found knowledge to only conduct the six steps once, you can easily make this a recurring event. Because even though your facility may not change, the air system will, new leaks may appear, items on the supply side may wear, demand side application may change as processes are added or modified.

Processes lead to continuous improvement.

Continuous improvement is a method that propels a system forward toward efficiency and improved outcomes and it is something that is needed to stay relevant. Even with the methods of solving a 3×3 cube, those methods continue to evolve and the main level of improvement is often on the person spending time with the process. If you want to discuss a compressed air application in your facility that could stand some improving or maybe you want to share your solve times on the 3×3 cube, don’t hesitate to reach out to me.

Brian Farno
Application Engineer