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.
One of the most common and dangerous hazards that occur within a manufacturing and production facility is the noise level within the plant. Noise is measured in units known as decibels. Decibels are a ratio of the power level of the sound compared to a logarithmic scale. If an employee is an exposed for too long to high levels of noise, they can begin to lose their hearing. That is where the OSHA 29 CFR 1910.95 regulation comes into play.
This OSHA standard doesn’t just provide the protection against noise in the work place but monitoring as well. Companies shall provide at no cost audiometric tests for all employees to ensure that no damage is being to the hearing of all personnel. This program is to be repeated every six months and the results are to be made accessible to all personnel.
Hearing is very important to our everyday lives and must be protected due to the fact that once it is damaged hearing loss cannot be lost be repaired. The OHSA 29 CFR 1910.95 is there to protect and monitor this dangerous hazard in the workplace so that all employees can go home safe and sound.
Here at EXAIR we design all of our products to safe and quite. Weather it is using one of our mufflers for vortex tubes or E-vac’s or one of our super air nozzles we strive to meet and exceed the OSHA standard. One could also purchase EXAIR’s Digital Sound Level Meter which can give a accurate and responsive reading of how loud your compressed air sources are.
For more information on EXAIR’s Digital Sound Level Meter and any of EXAIR‘s Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.
Cody Biehle Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
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.
The Second Step to optimize your compressed air system is to Find and fix leaks in your compressed air system. The reason leaks are important to find and fix is because they can account for 20-30% of a compressors total output. A compressed air leak fixing process can save 10-20% of that lost volume.
Unintentional leaks will result in increased maintenance issues and can be found in any part of a compressed air system. Leaks can be found at a poorly sealed fitting, quick disconnects and even right through old or poorly maintained supply piping. Good practice will be to develop an ongoing leak detection program.
The critical steps needed for an effective leak detection program are as follows:
Get a foundation (baseline) for your compressed air use so you have something to compare once you begin eliminating leaks. This will allow you to quantify the savings.
Estimate how much air you are currently losing to air leaks. This can be done by using one of two methods.
Load/Unload systems, where T= Time fully loaded and t=Time fully unloaded:
Leakage percent = T x 100
(T + t)
Systems with other controls where V=cubic feet, P1 and P2=PSIG, and T=minutes
Leakage = V x (P1-P2) x 1.25
T x 14.7
Know your cost of compressed air so you can provide effectiveness of the leak fixing process.
Find, Document and Fix the leaks. Start by fixing the worst offenders, fix the largest leaks. Document both the leaks found and the leaks fixed which can help illustrate problem areas or repeat offenders, which could indicate other problems within the system.
Compare the baseline to your final results.
Repeat. We know you didn’t want to hear this but it will be necessary to continue an efficient compressed air system in your plant.
After getting a baseline measurement of the air consumption in your facility and locating and fixing leaks in your system, it’s time to begin implementing some changes. Step 3 of the 6 Steps to Optimizing Your Compressed Air System covers upgrading your blowoff, cooling, and drying operations using engineered compressed air products.
This step can have the most impact when it comes to your bottom line. The energy costs associated with the generation of compressed air make it one of the most expensive utilities for any industrial environment. Because of this, we need to ensure that the places in your facility that are using compressed air are doing so efficiently.
EXAIR manufactures a variety of products that can help to ensure you’re using your compressed air in the best way possible. What it may seem simple, easy, and cheap to use something like an open-ended pipe or tube for blowoff, the fact of the matter is that the volume of air that these homemade solutions use quickly make them more expensive. Super Air Nozzles have been designed to entrain ambient air along with the supplied compressed air, allowing you to achieve a high force from the output of the nozzle while keeping compressed air usage to a minimum. In addition to saving air, they’ll also provide a significant reduction in overall sound level.
Another product that can be used to increase the efficiency of your blowoff processes is the Super Air Knife. Available in lengths ranging from 3”-108” and in a variety of materials, the Super Air Knife is the ideal replacement for inefficient drilled pipes. Again, it may seem cheaper to just drill a few holes in a pipe whenever you need to cover a wide area but the volume of air consumed in addition to the incredibly high sound level will quickly drain your compressor. The Super Air Knife is also designed to entrain ambient air, at a rate of 40:1! Allowing you to take advantage of the free ambient air in addition to the supplied air.
Let’s compare the costs difference between a homemade drilled pipe and EXAIR’s Super Air Knife. The Super Air Knife has a precisely set air gap across the full length of the knife, allowing for an efficient and quiet laminar airstream. When compared to a drilled pipe, the air consumption is dramatically reduced as is the sound level. For example, let’s take an 18” section of drilled pipe, with 1/16” diameter holes spaced out every ½”. At 80 PSIG, each hole consumes 3.8 SCFM. With a total of 37 holes, this equates to a total of 140.6 SCFM.
3.8 SCFM x 37 = 140.6 SCFM
A Super Air Knife, operated at 80 PSIG with .002” stock shim installed will consume a total of 2.9 SCFM per inch of knife. An 18” SAK would then consume just 52.2 SCFM.
2.9 SCFM x 18 = 52.2 SCFM
140.6 SCFM – 52.2 SCFM = 88.4 SCFM saved
Replacing an 18” drilled pipe with a Super Air Knife represents a total reduction in compressed air consumption of 63%! How much does this equate to in $$$? A reasonable average of cost to generate compressed air is about $0.25/ 1000 SCF. Let’s assume just a 40hr workweek:
88.4 SCFM x 60 mins x $0.25/1000 SCF = $1.33/hr
$1.33 x 40hr workweek = $53.20 USD
$53.20 x 52 weeks/year = $2,766.40 USD in yearly savings
The 2019 list price on a Model 110018 Super Air Knife is $397.00. By replacing the homemade solution with an 18” Super Air Knife, the return on investment is just over 38 working days of an 8-hr shift. If your plant runs multiple shifts, or works on weekends, it pays for itself even quicker.
Not only are these homemade solutions expensive to operate, they’re not safe either. Familiarize yourself with both OSHA 29 CFR 1910.95(a) and 29 CFR 1910.242(b) and you’ll learn just how expensive it can be if you were to be found using these devices during a random OSHA inspection. Make sure you’re utilizing the most expensive utility as efficiently and safely as possible. If you need help with determining which products are best suited for your application, give us a call. Our team of Application Engineers is ready to help!
EXAIR offers the model 9104 Digital Sound Level Meter. It is an easy to use instrument for measuring and monitoring the sound level pressures in and around equipment and other manufacturing processes.
Sound meters convert the movement of a thin membrane due to the pressure waves of sound into an electric signal that is processed and turned into a readable output, typically in dBA. The dBA scale is the weighted scale that most closely matches the human ear in terms of the sounds and frequencies that can be detected.
Noise induced hearing loss can be a significant problem for many workers in manufacturing and mining. To protect workers in the workplace from suffering hearing loss OSHA has set limits to the time of exposure based on the sound level. The information in the OSHA Standard 29 CFR – 1910.95(a) is summarized below.
The EXAIR Digital Sound Level Meter is an accurate and responsive instrument that measures the decibel level of the sound and displays the result on the large optionally back-lit LCD display. There is an “F/S” option to provide measurement in either ‘slow’ or ‘fast’ modes for stable or quickly varying noises. The ‘Max Hold’ function will capture and hold the maximum sound level, and update if a louder sound occurs.
If you have questions about the Digital Sound Level Meter, or would like to talk about any of the quiet EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
If you’re a follower of the EXAIR Blog, you’re probably well aware that compressed air is the most expensive utility in an industrial environment. The average cost to generate 1000 Standard Cubic Feet of compressed air is $0.25. If you’re familiar with how much air you use on a daily basis, you’ll understand just how quickly that adds up.
To make matters worse, many compressed air systems waste significant amounts of compressed air just through leaks. According to the Compressed Air Challenge, a typical plant that has not been well maintained will likely have a leak rate of approximately 20%!! Good luck explaining to your finance department that you’re carelessly wasting 20% of the most expensive utility.
The best way to save energy associated with the costs of generating compressed air is pretty straightforward and simple: TURN IT OFF! Placing valves throughout your distribution system allows you to isolate areas of the facility that may not need a supply of compressed air continuously.
Even a well-maintained system is going to have a leakage rate around 10%, it’s darn near impossible to absolutely eliminate ALL leaks. By having a valve that allows you to shut off the compressed air supply to isolated areas, you’re able to cut down on the potential places for leaks to occur.
You’re likely not running each and every machine continuously all day long, if that’s the case why not shut off the air supply to those that aren’t running? When operators go to lunch or take a break, have them turn off the valves to prevent any wasted air. The fact of the matter is that taking this one simple step can truly represent significant savings when done diligently.
You wouldn’t leave your house with all the lights and TV on, so why leave your compressed air system running when it’s not in use? Even if everyone’s left for the day, leaks in the system will cause the compressor to keep running to maintain system pressure.
Taking things one step further, EXAIR’s Electronic Flow Control (EFC) utilizes a solenoid controlled by photoelectric sensor that has the ability to shut off the compressed air when no part is present. If you’re blowing off parts that are traveling along a conveyor with space in between them, there’s no need to continuously blow air in between those parts. The EFC is able to be programmed to truly maximize your compressed air savings. The EFC is available in a wide range of different capacities, with models from 40-350 SCFM available from stock and systems controlling two solenoid valves for larger flowrates available as well.
It’s no different than turning off your house lights when you leave for work each day. Don’t get caught thinking compressed air is inexpensive “because air is free”. The costs to generate compressed air are no joke. Let’s all do our part to reduce energy consumption by shutting off compressed air when it isn’t necessary!