So it was 19°F (-7°C) when I walked outside this morning. The layer of ice on my windshield was thin, but particularly stubborn, and I muttered under my breath. I have no business complaining about the cold…see, I moved to Ohio (on purpose) from Florida, in 1991. In November, to be exact. I still remember where I surrendered my “complain-about-the-cold” card:
Why am I writing a blog about solutions to heat problems when, even though I do have a really nice pair of gloves, my fingers still aren’t even really thawed from ice removal duty this morning? Well, I’ve got three reasons:
1. Outside temperature doesn’t necessarily have any bearing at all on the temperature inside. Sure; there’s a reason we call July and August “Cabinet Cooler Season” – summer heat will do a number on sensitive electronic & control panels in spaces with no climate controls, but the problem goes away as winter approaches. In fact, there’s even such as thing as a cabinet HEATER, if the equipment in question is exposed to the elements. Sometimes, though, heat is an issue year ’round…think blast furnaces, boiler rooms, foundries, chemical plants. If your process generates heat, it’ll affect a control panel in the dead of winter just the same as on the dog days of summer. We can quickly and easily specify the right Cabinet Cooler System for you with just a few key pieces of data…here’s a link to our Cabinet Cooler Sizing Guide if you want to find out.
2. It’s not winter all over the world. Here in the Midwest United States, I full well realize we’re just gearing up for windshield scraping, snow shoveling, slipping-on-the-ice (some people call it skating and do it intentionally) season. But right now, our friends in the Southern Hemisphere are getting ready for heat waves, sunscreen, and (hopefully) air conditioning. So, in essence, they’re moving towards what we call “Cabinet Cooler Season.”
3. Our Cabinet Cooler Systems are so great, the 316SS Cabinet Cooler Systems with Electronic Temperature Control are actually up for Plant Engineering’s Product of the Year Award. Because of their 316SS construction, they’re optimally suited for installation in harsh or demanding locations. The Electronic Temperature Control offers continuous indication of internal temperature, and the ability to change the thermostat setpoint with the push of a button. If you’re a current user, and you agree that they’re great, we’d appreciate your vote. If not, I’m reluctant to encourage you to vote for it, but I suppose I can’t stop you from taking my word for it…
If you’d like to talk about protecting sensitive electronics from the heat, or from the environment, or both, I’d love to hear from you…give me a call.
If you’ve ever cleaned around the house (and who hasn’t?), you’re probably familiar with atomized liquid spraying…it’s what happens when you squeeze the trigger on that bottle of cleaner that breaks down the stove top grease in the kitchen and the ring-around-the-tub in the bathroom.
There’s a variety of industrial and commercial applications that require an atomized liquid spray too…applications that are beyond the scope of an operator with a trigger-operated spray bottle. That’s where EXAIR Atomizing Spray Nozzles come in. We have three types: Internal Mix, External Mix, and Siphon Fed. Depending on what you want to spray, and how you want to spray it, one of these is likely going to work better than the others for you. Today, we’re going to examine the Internal Mix Atomizing Spray Nozzles.
Better mist: Because the liquid & air come together inside the air cap, this results in very fine atomization.
Range of adjustment: Regulating either the liquid or air pressure supply will change the flow rate AND the flow pattern, giving each individual nozzle a wide performance band. The needle valve can “fine tune” the flow and pattern with even greater precision.
Area of coverage: With five patterns (Narrow or Wide Angle Round, Flat Fan, Deflected Flat Fan, and 360° Hollow Circular) and 72 distinct models to choose from, you can get spray patterns from 2″ (1/8 NPT Narrow Round Model AN8010SS) to 13 feet (1/2 NPT 360° Hollow Circular Model AT5010SS.)
Flow rate: Again, because of the many models available, you can get from 0.6 gallons/hour (Model AN8010SS again) to 264 gallons/hour (1/2 NPT Wide Angle Round Model AW5030SS.)
No-Drip option: The standard Models have a needle valve, which, as mentioned above, gives you the ability to make minute changes to the flow rate & pattern. If the application calls for rapid on/off control, or the chance of an errant drip after flow is not stopped might be a problem, the needle valve can be replaced with a No-Drip assembly. This positively shuts off liquid flow, at the exit of the liquid cap, when air pressure is secured.
Easy installation: All of our Atomizing Spray Nozzles have female NPT (1/8, 1/4, or 1/2) ports. The 1/8 and 1/4 NPT models can be adequately supported – and positioned – with a Stay Set Hose, and all models (even the 1/2 NPT) can be used with an appropriately sized Swivel Fitting. If you want to use your own tubes or hoses, we’ve got “clip-in” style Mounting Brackets.
Interchangeability: The only difference between any model of the same-size Atomizing Spray Nozzle is the Liquid and/or Air Cap. If your application’s liquid spray requirements change, or vary, you don’t need to replace the whole nozzle; just one (or in some cases, both) of the caps.
In the world of compressed air blow off solutions, there are a number of options which customers must consider. Should the plant maintenance personnel configure something on-site? Is there a low-cost option available from a catalog warehouse? Or, is there an engineered solution available – and if there is, what does this even mean?
Ultimately, the exercise in comparing these options will help select the option best for the application and best for the company. In order to make these comparisons, we will consider each option based on the following attributes: Force, sound level, safety, efficiency, repeatability, and cost. These are the factors which impact the ability to perform as needed in the application, and effect the bottom line of the company
Blow off applications require a certain amount of force in order to perform the desired task. If the blow off is in a bottling line, for example, we will aim for a lesser force than if blowing off an engine block. But, no matter the application need, we will want to consider the ability of the solution to provide a high force, high impact blow off. Homemade and commercially mass-produced nozzles produce low-to-mid level forces, which translates to a need for more compressed air to complete a task. Engineered nozzles produce high forces, minimizing compressed air use.
Have you ever been to a concert and felt your hearing reduced when you left? This can be the case for personnel in industrial environments with unregulated noise levels. Homemade or non-engineered blow off solutions carry the risk of increased sound levels which are outside of the acceptable noise level limits. EXAIR engineered nozzles, however, are designed to minimize sound level for quiet operation and continual use.
Workplace safety is a serious matter for everyone from shop floor personnel to executive management. Whether you’re working with or near a compressed air operated device, or your making decisions for your company which have to do with the compressed air system, safety is undoubtedly a priority. Unfortunately, homemade and commercially available nozzles normally fail to meet OSHA standards for dead-end pressure requirements (OSHA Standard 29 CFR 1910.242(b)). This means that these solutions can pose a risk of forcing compressed air through the skin, resulting in an embolism which can cause severe harm or even death.
EXAIR nozzles, however, are designed to NEVER exceed dead-end pressure limits and to provide an escape path for airflow in the even the nozzle is blocked. This safety aspect is inherent in ALL EXAIR designs, thereby adding safety to an application when an EXAIR product is installed.
Compressed air is the most expensive utility in any facility. Energy enters as an electrical source and is converted into compressed air through a compressor where up to 2/3 of this energy is lost as heat. The resulting 1/3 of converted energy is then piped throughout a facility as compressed air, where up to 1/3 of the air is lost to leaks. With this in mind, maximizing the efficiency of a nozzle solution becomes imperative. A homemade solution or commercial nozzle does not maximize the use of the compressed air. The result is a need to increase flow or increase pressure, both of which result in higher energy costs.
EXAIR nozzles are designed for maximum force per CFM. This means that any of our nozzles will produce the highest force at the lowest possible compressed air consumption. This, in turn, reduces demand on the compressed air system and allows for a lower energy requirement. Less energy demand means less energy costs, which goes straight to the bottom line of your company.
When installing a nozzle solution, it is important to have the same force and flow from each unit. If a solution needs to be replicated, balanced, or adjusted in any way, having various forces and flows from a homemade setup will induce difficulty and could make changes impossible. Line speed or volume increases may not be possible due to variance in the output flow and forces from homemade setups, but an engineered solution will produce the same output every time. This means you can adjust the nozzles as needed to achieve the perfect solution in your application.
For many customers and businesses, the most important aspect of any solution comes down to cost. Will the solution work? And, how much does it cost? When it comes to a homemade or commercial blow off solution, it may or may not work, and it will have a low purchase cost. But, the purchase price isn’t the whole story when working with compressed air. The real cost of an item is in the operation and use. So, while a homemade solution will be cheap to make and install, it will be EXPOENTIALLY more expensive to operate when compared to an engineered solution. An excellent example is shown above. An open copper tube is compared to an EXAIR model 1102 Mini Super Air Nozzle. The copper tube cost only a few dollars to install, many times less than the EXAIR nozzle, but it costs almost two THOUSAND dollars more to operate in a year. Translation: Install a cheap blow off solution and pay for it in utility costs.
EXAIR nozzles and blow off solutions are engineered for maximum force, lowest possible noise level, OSHA safety compliance, maximum efficiency, and maximum repeatability. These factors allow for options which not only solve application problems, but also do so with the lowest total cost possible. If you have an application in need of a blow off solution, feel free to contact our Application Engineers. We’ll be happy to help. And, if your curious about the benefit of our products in your application, consider our Efficiency Lab. We will test your existing setup next to our recommended EXAIR solution and provide the impact to your bottom line.
What is laminar flow and turbulent flow? Osborne Reynolds popularized this phenomenon with a dimensionless number, Re. This number is the ratio of the inertial forces to the viscous forces. If the inertial forces are dominant over the viscous forces, the fluid will act in a violent and chaotic manner. The formula to determine the Reynolds number is as follows:
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)
The value of Re will determine the state in which the fluid (liquid or gas) will move. If the Reynolds number, Re, is below 2300, then it is considered laminar (streamline and predictable). If Re is greater than 4000, then it is considered turbulent (chaotic and disarrayed). The area between these two numbers is the transitional area where you start to get small eddy currents and velocities in a non-linear direction. When it comes to effective blowing, cleaning and lower noise levels, laminar flow is optimal.
Let’s do a comparison of Reynolds numbers between the EXAIR Super Air Knife and a blower-type air knife. Both products are designed to clean and blow off wide areas like conveyor belts. The EXAIR Super Air Knife is powered by compressed air, and the blower-type air knife is powered by an air blower. The main difference between the two products is the dimension of the slot opening. The Super Air Knife has a gap opening of 0.002″ (0.05mm). It uses the force of the compressed air to “push” it through the small opening to create a strong velocity. A blower does not generate a high force, so the opening of the blower-type air knife has to be larger to overcome any back pressure the opening creates. The gap opening is typically 0.5″ (13mm). From Equation 1 above, the gap opening helps determine the hydraulic diameter, Dh. The hydraulic diameter is an equivalent tube diameter from a non-circular flow area. Since both the Super Air Knives and blower-type air knives have rectangular cross sections, the Dh can be calculated as follows:
Equation 2: Dh = 2 * a * b/ (a + b)
Dh – Hydraulic Diameter (feet or meter)
a – Gap Opening (feet or meter)
b – Gap Width (feet or meter)
If we compare for example a standard 12″ wide air knife, we can calculate the hydraulic diameter, Dh, by using Equation 2:
The exit velocity of the Super Air Knives can be changed by regulating the air pressure. The higher the air pressure, the higher the velocity. The blower type air knives can use a blower with a variable frequency drive (VFD) to change the exit velocity . A reasonable air pressure for the Super Air Knife is 80 PSIG, and the exit velocity is near 540 ft/sec (164 m/s). To equate this to a blower system, the size of the blower will determine the maximum velocity. To do this comparison, I will use the same velocity as the Super Air Knife. With the kinematic viscosity of air, it has a value of 0.000164 ft^2/sec (0.000015 m^2/sec) at 70 deg. F (21 deg C). Now we have all the information for the comparison, and we can now find the Reynolds number from Equation 1:
As you can see from the above calculations, the Super Air Knife has a Reynolds number, Re, below 2300. The flow characteristic is in the region of laminar (predictable and streamline). The blower air knife has a Reynolds number, Re, above 4000. The flow dynamic coming out of the blower-type air knife is turbulent (chaotic and disoriented). To better show the difference in laminar flow and turbulent flow, I have a picture below that shows both states with water as a fluid (being that air is an invisible fluid). Here is an example of water coming out of a drain pipe at Cave Run Lake (first picture below). With the inertial forces much higher than the viscosity of the water, it is in a turbulent state; loud and disorderly. Reynolds number is greater than 4000. The water is traveling in different directions, even upstream. As the water flows into the mouth of the river after the channel (second picture below), the waves transform from a violent mess into a quiet, calm stream flowing in the same direction. This is laminar flow (Re is less than 2300).
With the engineered design of the Super Air Knife, the thin slot helps to create that laminar flow. All the air is moving in the same direction, working together to give a higher force to remove debris. If you have turbulent flow like that of a blower air knife, the noise level is much higher, and the disoriented forces are less effective in blowing. Turbulence is useful for mixing, but horrible for trying to clean or wipe a conveyor belt. If you have any open pipes, drilled pipes or blower-type air knives in your application, you should try an EXAIR product to see the difference. An Application Engineers can help you take advantage of laminar airflow.
I wrote a blog a few weeks ago about increasing efficiency with EXAIR Super Air Nozzles. In the application for that blog we used engineered nozzles to place open pipes, resulting in an efficiency increased of ~65%. This week’s installment of efficiency improvements boasts similar figures, but through the replacement of misused liquid nozzles rather than open pipe.
The image above shows a compressed air manifold with a number of nozzles. BUT, the nozzles in this manifold are not compressed air nozzles, nor do they have any engineering for the maximization of compressed air consumption. These are liquid nozzles, usually used for water rinsing.
In this application, the need was to blow off parts as they exit a shot blasting machine. When the parts exit the shot blasting process they are covered in a light dust and the dust needs to be blown away. So, the technicians on site constructed the manifold, finding the liquid nozzles on hand during the process. They installed these nozzles, ramped up the system pressure to maintain adequate blow off, and considered it finished.
And, it was. At least until one of our distributors was walking through the plant and noticed the setup. They asked about compressed air consumption and confirmed the flow rate of 550 m³/hr. (~324 SCFM) at 5 BARG (~73 PSIG).
The end user was happy with the performance, but mentioned difficulty keeping the system pressure maintained when these nozzles were turned on. So, our distributor helped them implement a solution of 1101SS Super Air Nozzles to replace these inappropriately installed liquid nozzles.
By implementing this solution, performance was maintained and system pressure was stabilized. The system stabilization was achieved through a 61% reduction in compressed air consumption, which lessened the load on the compressed air system and allowed all components to operate at constant pressure. Calculations for this solution are shown below.
Compressed air consumption of (9) model 1101SS @ 5.5 BARG (80 PSIG): 214 m³/hr. (126 SCFM)
Total compressed air consumption of 1101SS Super Air Nozzles:
Air consumption of 1101SS nozzles compared to previous nozzles:
Engineered air nozzles saved this customer 61% of their compressed air, stabilized system pressure, improved performance of other devices tied to the compressed air system, and maintained the needed performance of the previous solution. If you have a similar application or would like to know more about engineered compressed air solutions, contact an EXAIR Application Engineer.
I had the pleasure of discussing a spot cooling application with a customer this morning. He wanted to get more flow from his Adjustable Spot Cooler, but still keep the temperature very low. He machines small plastic parts, and he’s got enough cold flow to properly cool the tooling (preventing melting of the plastic & shape deformation) but he wasn’t getting every last little chip or piece of debris off the part or the tool.
After determining that he had sufficient compressed air capacity, we found that he was using the 15 SCFM Generator. The Adjustable Spot Cooler comes with three Generators…any of the three will produce cold air at a specific temperature drop; this is determined only by the supply pressure (the higher your pressure, the colder your air) and the Cold Fraction (the percentage of the air supply that’s directed to the cold end…the lower the Cold Fraction, the colder the air.)
Anyway, the 15 SCFM Generator is the lowest capacity of the three, producing 1,000 Btu/hr of cooling. The other two are rated for 25 and 30 SCFM (1,700 and 2,000 Btu/hr, respectively.)
He decided to try and replace the 15 SCFM Generator with the 30 SCFM one…his thought was “go big or go home” – and found that he could get twice the flow, with the same temperature drop, as long as he maintained 100psig compressed air pressure at the inlet port. This was more than enough to blow the part & tool clean, while keeping the cutting tool cool, and preventing the plastic part from melting.
If you’d like to find out how to get the most from a Vortex Tube Spot Cooling Product, give me a call.
Earlier this morning I received a phone call from a gentleman in search of a more efficient compressed air solution. The application was to remove thermoformed plastics from a mold immediately after the mold separates. In the current state, the application is consuming ~40% of the available compressed air in the facility through the use of (9) ¼” open pipes, consuming a confirmed 288 SCFM at 60 PSIG. Due to the use of an open pipe, this customer was facing a safety and noise concern through the existing solution.
After discussing the application need and the desire to reduce compressed air use, reduce noise, and add safety, we found a suitable solution in the 1101 Super Air Nozzle. Installing (9) of these EXAIR nozzles will reduce the compressed air consumption by over 65%!!! Calculations for this savings are below.
Existing compressed air consumption: 288 SCFM @ 60 PSIG
Compressed air consumption of model 1101 @ 60 PSIG: 11 SCFM
Total compressed air consumption of (9) 1101 nozzles:
This is the percentage of air which the new EXAIR solution will consume. To put it another way, for every 100 SCFM the current solution consumes, the EXAIR solution will only require 34.38 SCFM. Installing these EXAIR nozzles will result in lower operational cost, lower noise levels, and increased safety for this customer – all while maintaining or improving the performance of the blow off solution in this application.
EXAIR Application Engineers are well versed in maximizing efficiency of compressed air systems and blow off needs. If you have an application with a similar need, contact an EXAIR Application Engineer. We’ll be happy to help.