The Nex Flow Difference: Why we treat our materials differently?
Nex Flow Air Products Corp. sets itself apart from its competitors by doing a few things differently with the materials that we use in manufacturing our products. While some producers are actually quite similar in product as to how they deal with material, we stand out in four specific areas as to what we do with the materials of manufacture. Differences for Nex Flow are as follows:
Anodized aluminum parts
Powder coated parts
No Plastic in our vortex tubes
We do not mix aluminum and stainless steel in our vortex tube packages
Anodized Aluminum parts
We make it a point to anodize our aluminum air knives, amplifier, air jets, air wipes and air operated conveyors. It is actually much easier (and certainly less costly) to produce these items without anodizing due to the importance of efficient aerodynamic design. When the products are anodized the surface changes, even if the change is very small, it makes it more difficult to keep a flat part flat (i.e. air knives). But, we CAN do and we do it because of the value the anodizing adds benefits to the products. Anodizing helps guard against the effects of the factory environment on the aluminum. Unprotected aluminum will form a powdering while oxide over time. Anodizing keeps the product looking better and longer even when using dissimilar metals in assembly, stainless shims, stainless screws, with aluminum bodies, it protects the accessories from even minor effects of cathodic corrosion. Cathodic corrosion can occur in a highly humid environment or if the parts get wet. Dissimilar metals can act like a battery where the more active metal can corrode unless there is some form of protection. You can see this effect, for example, with rust around screws used on some buildings or machines because the screws are of one material while the metal it is screwed into is another. When paint wears away, it leaves unprotected metal that is more electrically “active” than the metal in the screw. By anodizing and protecting our product, Nex Flow ensures that our accessories will last longer and look better over time.
Powder Coated parts
Some of our cast zinc parts, specifically our Air Edger flat jet nozzles and cast Fixed X-Stream Air Amplifier, also have powder coating. It provides a much better finish and look to the product and again, extra layer of protection from the factory environment. Powder coating is an excellent protection in a factory environment. Powder coating parts adds intrinsic value to the products to the betterment of the customer providing a product that is longer lasting look better through time.
No Plastic in Vortex Tubes
Most manufacturers of vortex tubes use injection molded plastic “generators” which are used in the unit to initiate the compressed air spinning effect. Nex Flow machines their “brass” generators for that purpose instead of plastic. While plastic would be much less costly, brass offers a few advantages. Injection molding plastic will have some variations in production, especially as the mold wears out. By machining the metal generators we have much greater consistency with the parts which translates into much greater consistency in performance from one vortex tube to the next. Vortex tubes consist of several parts and of course, each part has a certain tolerance in manufacturing. Nex Flow has very tight tolerances on each part and the generators especially require very tight tolerances. The more pieces involved in assembling a part, the more the cumulative effect on the overall variation in tolerance and therefore performance since the operation of all Nex Flow products are based on aerodynamic shapes.
As the generator is such a critical component in a vortex tube, we recognize the need to use metal instead of plastic. Another advantage of using metal, in our case brass, instead of plastic is that plastic can possibly crack over time. If the compressed air supply is dirty the generator can also build up dirt and engrain itself, hence requiring replacement. The metal ones we use are easily cleaned. Sometimes vortex tubes or their packaged versions are used in very hot environments so the parts must be able to hold up in high temperature areas, especially when not operating. In these cases even competitive units replace their plastic generator with metal. Nex Flow vortex tubes and many of their packages are therefore more flexible in the environments where they can be used. While competitors would charge extra for a special product, our standard product can generally be used instead.
We do not mix Aluminum and Stainless Steel
Our vortex tube packages include tool coolers, mini coolers, adjustable coolers, panel coolers, etc. Of particular importance is the materials used in a panel cooler used for cabinet enclosure cooling and camera cooling. Many manufacturers will use a stainless steel vortex tube packages as a control panel cooler using aluminum housing and attachments. While not a problem in relatively benevolent factory environments, it can become an issue in very humid area or in applications where they are used in wash down conditions. Cathodic corrosion can occur described earlier with dissimilar metals with air knives. On one visit to a customer there was actually a competitive vortex tube cooling system with a big hole on the side of the assembly. Cabinet cooling applications are very critical because you do not want any possibility for moisture getting into the control panel. This is the reason vortex coolers should have the proper approvals to insure this does not happen (such as Underwriters Laboratory testing and approval). Cabinet Coolers are essentially vortex tubes with a cover and some system to prevent moisture from getting inside of the cover and possibly then into the cabinet. This cover was aluminum and the vortex tube another material. The environment was a relatively wet environment, so over time cathodic corrosion cause the aluminum to corrode and create a hole in the protective cover. Thus, creating a potential risk for water to get into the electrical cabinet. It is for this very reason (preventing cathodic corrosion) that Nex Flow only has stainless steel covers for their stainless steel vortex tubes. Similarly with all other packages systems, whether they are tool coolers or adjustable coolers, the packages are made with stainless steel only and not a mixture of stainless steel and aluminum.
It’s a Wrap
These are some of the reasons why Nex Flow treats their materials differently. While some of these “differences” in material handling and treatment can be more costly from a manufacturing point of view, they do offer significant added value to the products and a benefit to the customer, and still with a very competitive price.
Wind tunnels are large tubes with air moving inside. These tunnels are used to test models of aircraft or other flying objects on their actions in flight. These models are scaled down versions of actual objects that will be built. Researchers and institutions around the world like NASA, uses wind tunnels to learn more about how an aircraft and spacecraft will fly. But it is not just flying machines that are tested. These Wind chambers are also used to test how an automobile shape, or windshield design will behave in environments with strong winds. Aerodynamics is the study of the flow of air or gases around an object in motion. Essentially these tunnels are hollow tubes with controllable fans at one end to test objects aerodynamics ensuring safety and performance of machines. Airplane builders use NASA wind tunnels to test new airplane designs. Credits: NASA
Frank H. Wenham (1824-1908), along with his colleague John Browning, invented the wind tunnel and built the first one in 1871. He described it as “a trunk 12 feet long and 18 inches square, to direct the current horizontally, and in parallel course.” As a British marine engineer he studied the problems of human flight and had many publications. He also made a huge influence in the development of aeronautics. Their experiments showed that high aspect ratio wings – long and narrow—had a better lift-to-drag ratio than short stubby wings with the same lifting area. Wenham may have been the first scientist to use/coined the word “aeroplane”. Aviation writer Carroll Gray says Wenham’s work may have been an important influence to the Wright brothers.
As mentioned above, wind tunnels typically use powerful fans. But – it is possible to use Nex Flow compressed air operated Air Amplifiers instead of fans for a miniature wind tunnel. To get the system to work, the gap setting on the Air Amplifiers will have to be increased to approach the power needed for testing even a very small object. Although there are limitations to using compressed air for wind tunnel emulation – they do offer some advantages like having a lower noise level and their ability to be combined with vortex tube technology for testing at sub-zero temperatures. Powerful fans overcome back pressure created by the length and overall volume in the tunnel. Compressed air amplifiers however cannot be “revved up” like a motor and are subject to this back pressure limiting the length and volume of a tunnel where it can be used. However for very light and small objects, it is conceivable to use an Air Amplifier to operate a miniature wind tunnel. Air Amplifiers take compressed air that is consumed and converts the pressure normally lost as pressure drop and noise into high velocity and high laminar flow. With fans you can control this velocity and flow by making the fan turn faster or slower. With Air Amplifiers you have some limited control with input pressure but in a much more narrow range which should suffice for a small miniature tunnel. A common setup at exhibitions is to attach an Air Amplifier to a stand and have the amplified airflow support a beach ball which can be held a few feet above the vertically aimed Amplifier. The object tested in an Air Amplifier operated miniature wind tunnel would have to be in the low weight range of a beach ball to be useful. A powerful compressed air operated engineered nozzle, or a series of engineered air nozzles might be paced at one end of a miniature wind tunnel for more force. After a short distance, the combined airflow could produce enough velocity and flow to be useful for testing small, light objects. One advantage of both using compressed air amplifiers or laminar nozzle is the lower noise level than you would get from a powerful fan.
Vortex tube technology however, does offer one advantage for a special type of wind tunnel. A vortex tube is a device which takes compressed air and divides it up into a hot and cold stream. This cold stream of air flow can go to very low, sub-zero temperatures. Vortex tube commercially are available in air consumption ranges of 2 to 150 SCFM. However, there is no reason that a vortex tube cannot be made much larger to consume several thousand SCFM. In some research applications for wind tunnels it is necessary to study aerodynamics at sub-zero temperatures (i.e. the behavior of military aircraft in arctic or subarctic conditions). A much larger vortex tube consuming one thousand SCFM or even more can produce very cold temperatures of -40 ˚C and even colder if the compressed air supply is cooled further. While it would seem to be uneconomical to use such high volumes of compressed air, that high energy cost is offset by the fact that you do not have to cool the air to the sub-zero temperatures required for testing. Also, the efficiency in the production of the cold temperature actually goes up as you increase the size of the vortex tube. Let’s presume you have 10,000 SCFM of compressed air supply. With vortex tubes the temperature drop increases (you get colder temperatures) the more air you exhaust at the “hot end”. So if only 30% (3000 SCFM) goes out the cold end to get that -40 degrees Celsius. The cost of cooing 3000 SCFM of a fan produced air flow to that cold temperature using a more traditional means of cooling will be very high. You also will be using refrigerant which will be costly, and need maintenance. In using a special vortex tube you only have the compressors and the wind tunnel taking the flow, at the low temperatures you want. This minimizes any maintenance involved. It is actually a very simple system.
So while there are certainly not a great deal of applications where a wind tunnel is needed that produces such low sub-zero temperature airflow, there are certainly enough when dealing with some military and space equipment applications where aerodynamic tests results under extremely low temperatures are required. In this case, using a special large vortex tube is a possibility. Such special wind tunnel has been built in the past with very large vortex tube design.
For unique applications such as the above – Nex Flow has experience in special vortex tube design. Some years ago a two meter long vortex tube was developed for an application (not a wind tunnel however) which used natural gas as the medium instead of compressed air. The parameters of the application had to be addressed to develop the optimum design and the supply gas was at very high pressure. The application remains proprietary but it does indicate that vortex tube technology can be adapted and made effective and economical for special applications where cold temperatures or overall cooling is necessary and where using traditional cooling would not be as effective or economical.
So for wind tunnel applications, Air Amplifiers (and even Engineered Air Nozzles or jets) can apply to miniature wind tunnel for small and lightweight objects. If the wind tunnel requires sub-zero temperatures, vortex tube can be integrated as part of the system. Do note that as these are two different things entirely, you connect a vortex tube to an air amplifier
Compressed air is safe, reliable, and used in packaging products. The compressed air systems move materials from one area of the factory to another, perform blow-off, part drying, and align products for packaging. Bakeries use compressed air for blow-off applications, while others use compressed air to clean containers before filling them with products. Compressed air technology is also used to cut, sort, shape, and convey products, such as food, from one location to another in a factory.
Cartons are also formed, filled, and sealed using compressed air. The quality of compressed air can vary widely depending on its application. The food industry requires the highest level of safe, clean compressed air to handle and package goods. Pharmaceutical industries also require more stringent clean air than other industrial applications because they are either ingested or injected.
Clean, high-quality compressed air is required in pharmaceutical and food packaging to ensure consumer safety and prevent product contamination. It is essential to have either no contact with the product or contact using pure air to avoid product recalls, damage to brand reputation, or litigation. Pneumatic systems are recommended because there is no chance of leaking oil as in hydraulic systems.
Pneumatic systems do not pollute or release contaminants into the atmosphere, so they are especially useful for packaging food products. These systems have no moving parts, so there is less maintenance and downtime compared to other systems.
Using Compressed Air in Packaging
Clean compressed air is essential for food and pharmaceutical processing and packaging operations. Compressed air must be purified, especially when the product is consumed. Compressed air conveyors are the best technology to ensure safe food quality. Contaminants include spores, solid particulate, vapors, and moisture. Oil is often not an issue with compressed air conveying systems, unlike hydraulic systems, which use oil as a medium.
To stop microorganisms and fungi growth, the dew points of air at line pressure must be -25 degrees Celsius (-15 degrees Fahrenheit). Standards have been developed that state very fine filtrations to prevent particulate and oil from contaminating food products.
How does Compressed Air Keep Products Dry and Free of Contaminants?
Equipment performance is only as good as the quality of air. Any atmospheric air contains some moisture and dirt. No matter how small the contaminants are initially, they are concentrated when the air is compressed as the air heats, its ability to hold water vapor increases. The vapor condenses into liquid when the air begins to cool as it travels downstream. Maintenance by plant operators can remove liquid, particles, and contaminants. Air dryers are installed to reduce moisture.
They lower the dewpoint of the compressed air to prevent water droplets from forming downstream. There are four types of dryers: Refrigerated, chemical, regenerative, and membrane or mechanical. Mechanical filters work with compressed air dryers to remove contaminants and water. There are three types of filters: Particulate, coalescing, and adsorption.
After the appropriate filter has been added to the conveying system to ensure that the compressed air equipment does not introduce contaminants, equipment that is used to blow off products before packaging is added, examples of this type of equipment include engineered nozzles and air knives. They conserve compressed air by using the Coandă effect to entrain surrounding air along with compressed air to create a high-flow velocity stream of air.
What are some things to remember when using Compressed Air Products for packaging?
If used as intended, compressed air will not generate biological, chemical, or physical hazards while packaging goods. The manufacturer is responsible for producing final products that are sanitized and free of contaminants such as oil, microorganisms, particulate or dust. Manufacturers that use the compressed-air system must carefully consider productivity and production costs against safety.
Compressed air used in packaging will often come into contact with the product. “Contact Application” is defined in the British Compressed Air Society (BCAS)/ British Retail Consortium (BRC) code of Practice for Food Grade Air code as “the process where compressed air is used as part of the production and processing including packaging and transportation of safe food production.” This means that packaging and moving products with compressed air is a contact application.
Other examples of compressed air contacting the product include blowing off the water after washing a product and before packaging, cooling a product to increase line speed, and blowing off excess ingredients (such as sugar) before cooking. Non-Contact Application is “the process where compressed air is exhausted into the local atmosphere of the food preparation, production, processing, packaging or storage.” Non-contact applications can be categorized into 2 additional sub-categories (high risk and low risk).
Using Compressed Air in Packaging
When designing a compressed air system for conveying, it is important to use filters and air purifiers to ensure compliance with various safety and manufacturing standards. The BCAS/BRC Code of practice recommends testing the machinery installation twice a year for contaminants such as microorganisms, particles (dirt and dust), humidity, and oil contamination. Refer to this article to learn more about the requirements in the food industry or the standards in the pharmaceutical industry.
With regards to filtration, a centralized air drying and filtration system should suffice if the pipes are relatively new in the facility. However – if the pipes are polluted or hard to clean – it is better to have both a centralized filter as well as a decentralized filter installed upstream of the point of use. New or cleaned pipes are also recommended of zinc-plated steel for food applications, V2A/V4A, compressed air-approved plastic, or aluminum.
How does it work?
The Packaging industry includes a wide variety of materials and products since almost every manufactured product is packaged: toys, food, soft drinks, beverages, cigarettes, cosmetics, brushes, kitchen accessories and more. All the products move down the assembly line before packaging. The packaging process consists of transportation lines made of pipes or ducts to carry a mixture of products and materials along a stream of air.
The pneumatic conveyor system consists of interconnected transition lines, hoses, cylinders, a gas compressor, standard cylinders, and gas (atmosphere). The compressor generates the air flow and transmits the material through a series of hoses. Manual or automatic solenoid valves control the air flow—a centrally located and electrically powered compressor powers cylinders, air motors, and other pneumatic devices. Pneumatic systems are controlled by a simple ON/OFF switch.
There are three conveyor systems that generate high-velocity air streams: a suction system/vacuum system, a pressure system, and a combined system.
A suction or vacuum is used to move light-free-flowing materials. The system operates at 0.5 atm below atmospheric pressure.
A positive pressure compressed air conveying system is used to push material from one point to another. This type of conveyor operates at a pressure of 6 atm or more.
The combined suction/pressure conveying system is used to convey material from several loading points (suction) to deliver to several unloading destinations (push).
What are some Nex Flow products applied to packaging items?
Pneumatic systems are highly recommended when manufacturing, moving or packaging any product that will be digested or inserted in a living organism, such as food or pharmaceutical goods, since there is no chance of contamination due to burst pipes or oil leaks. Nex Flow manufactures compressed air products that help companies to package goods by supplying machines used for industrial cooling (Vortex tubes), part cleaning, drying, and blow-off, and air-operated conveying before packaging.
Nex Flow engineered air optimization design improves safety while increasing manufacturing and packaging productivity and decreasing energy costs. The air-operated conveyor systems sold by Nex Flow can replace traditional conveyor belt systems, which have higher operational costs because they need to be regularly maintained.
Spot Cooling
Nex Flow pneumatic products provide the best spot cooling and blow-off solutions for materials before packaging. Vortex tubes convert compressed air into very cold air for spot cooling for industrial applications. Small vortex tube-operated mini-coolers and vortex cooling can provide extremely cold temperatures for spot cooling before packaging without refrigerants, such as CFCs or HCFCs. Vortex tubes improve factory safety and reduce noise for workers in a manufacturing environment.
Blow-Off Products
Effective, engineered blow-off products manufactured and sold by Nex flow include air knives, air amplifiers, air jets, and air nozzles. These products are another example of how Nex Flow strives to improve the safety of manufacturing and factory environments because they meet OSHA noise and pressure specifications. Among many other applications, air amplifiers are used to clean and dry parts and remove chips and part ejection.
Air knives and nozzles are used to flip open and close the tops of boxes during packaging. Air blade ionizers effectively remove static that could trap the dirt while using plastic wrap for packages.
Conveying Systems
Compressed air-operated conveying systems move materials and products at high speeds over long distances. Ring Vac Operated conveyors, and X-Stream Hand Vac are used for conveying materials where vacuum force is required to move products over long distances at high rates. Ring Vac Air operated conveyors were originally designed to help with bending and lifting goods. The speed of conveyors depends on the density of the materials (lbs./cubic foot), horizontal distance, and vertical lift.
A Ring Vac operated conveyor is a simple, low-cost solution to other pneumatic conveying systems. They are available in several materials depending on the application. Ring Vac operated systems are made of anodized aluminum or stainless steel. 316L Stainless Steel pneumatic conveyors are used when moving food and pharmaceutical products or packaging. It is available in regular and high-temperature stainless steel for high-temperature and corrosive environments.
The X-stream® Supreme Pneumatic Conveying System (XSPC) is an air-operated conveyor that uses compressed air for an efficient and power venturi action along the length of the non-clogging design. The compressed air system is designed to transport or vent lightweight items and raw materials for packaging at high rates over long distances.
The cost-effective systems are ideal for continuous or intermittent use since they are operated by a simple on/off switch and are controlled by a regulator. All Nex Flow conveyor systems are simple, easy to install and use, compact, portable, and maintenance-free.
Other benefits of compressed air-operated conveying systems are also reliable since there are no moving parts and low maintenance costs. These systems have no angles to collect contaminants such as moisture, particulate debris, or microbiological growth. They are safe for any factory environment because the system is powered by compressed air and not electricity.
Mufflers, filters, mounting systems, and static control for blowing off dust and debris from statically charged surfaces are available through Nex Flow to improve factory production and efficiency in assembly and packaging goods.
Trust Nex Flow to provide the most efficient, reliable, maintenance-free compressed air solutions for packaging your goods so that they are clean and safe for your customers.
Using Compressed Air in Packaging FEATURED PRODUCTS
Air Amplification Explained compressed air-operated amplifiers presume to reduce compressed air use and lower noise levels in blow-off and cooling applications. The term air amplifier is normally applied to annular-shaped units (called Air Amplifiers or Air Movers). However, the same technology used applies to air nozzles, air jets (which are essentially small Air Amplifiers), air knives (linear amplifiers), and some air wipe designs.
They work using the Coanda effect, which essentially is an effect in which a fluid (liquid or gas) clings to a surface as it flows in a laminar flow. You can see this effect by turning on the water tap in your kitchen at a low level, so the water flow is smooth. Put your finger just touching the flow, and it will bend the water flow as it slings to your finger. The same thing occurs with a compressed gas like air.
To achieve the best use of this Coanda effect other factors need to be considered such as the volume of the chamber that the compressed air exits to minimize any turbulence inside the chamber and minimize pressure losses. The number of and actual angles of these Coanda “angles” combined with internal designs where the compressed air is collected before exit determines the overall efficiency and performance of the compressed air used for blow-off.
As this air bends, it creates a vacuum behind it drawing in surrounding atmospheric air. This “converts” the pressure that is normally lost as pressure drops and noise into the flow. This is important. Several things occur as this additional mass flow is drawn in and mixed with the compressed air.
First, the overall force goes down because you mix with still (non-moving) atmospheric air. Secondly, the flow is dramatically increased because of this pressure conversion to flow. It is “converted energy” instead of “lost energy.” While the overall force goes down, overall kinetic energy remains high and laminar for some distance.
This means that whatever blow-off energy is required, it can perform that operation at a greater distance from the exit of the air than if compared to an open pipe or tube. And, of course, because lost energy is recovered, the noise levels drop. So when we state that air amplification is free, it is quite true, but with the caveat that overall force will be lower, but velocity and flow will both be much higher, all due to the extended laminar flow.
If air is blown with just an open pipe or tube, the exit creates a great deal of turbulence resulting in energy loss and high noise levels. This means that the force may be quite high near the exit, but it will dissipate quickly as you move away from the air exit.
There are some situations where high pressure is required. In those situations, an air amplification nozzle or device may not meet that force, such as removing heavy mud baked onto a surface or breaking off scale waste from metal. But the pipe used has to be close to the surface. However, except for those situations, air amplification technology certainly can be used instead, as the vast majority of applications where compressed air is used do not need the full high-pressure force of an airline.
One suggestion to reduce energy and noise is simply to reduce air pressure for blow-off and even cooling applications. After all, a 20% reduction in compressed air pressure will reduce the compressed air energy by 10%. If you reduce the pressure to 30 pounds from 80 pounds per square inch, that would yield a 25% reduction in energy. Noise will go down somewhat, but you will still have a great deal of turbulence at the air exit, and you will not get the “distance” for effectiveness that you would with an air amplifier.
But, even an air amplifying air nozzle will get anywhere from 30% to 40% or more energy reduction with the equivalent force, depending on the design of the air nozzle. For example, older cone-shaped air nozzle designs will reduce energy by 30% and create very high flow and velocity, which is especially ideal for cooling applications. The Nex Flow Air mag design reduces energy by over 40% and works with a powerful force and high flow, and high velocity with the laminar flow at a very long distance, as well as noise reduction.
The argument for that extra “free” energy from air amplification is therefore very compelling.
As was hinted at above, it is not just the flow profile and Coanda “angles” which affect performance. It is the internal design of an air amplifier and how the compressed air behaves internally that is also important. Minimizing internal turbulence is a major consideration in design. For example, you can take five different cone-shaped air nozzles from different manufacturers, test them side by side, and their performance and efficiency can vary by a wide margin.
In this case, efficiency can be defined as the force produced at a set distance divided by air consumption. There is a design called a Laval nozzle, for example, that was developed to produce less noise and improve energy. However, the noise level improvement is not significantly noticed due to the noise frequencies obtained, and the distance of effectiveness appears to be limited because, to make this design work, the efficient exit of the force-producing airflow has to be contained by a rather inefficient series of air flows from slots around the Laval opening, offsetting any other improvements.
The Coanda design combined with proper internal design appears to be the optimum methodology in air amplifier design.
Air jets are another example where the Coanda design makes a big difference. Air Movers or large annual Air Amplifiers, if very small, are called Air Jets. Most manufacturers of Air Jets have one Coanda angle to direct the air exiting the annual plenum. Nex Flow Air Jets have several specially designed Coanda angles and can produce the same high level of force and flow with 25% less energy and lower noise levels.
Large annual Air Amplifiers also have efficiency variations among different manufacturers because of internal and external design differences. A somewhat abused term that often comes up with annular Air Amplifiers is “amplification ratio”. One should be very wary of, frankly, ridiculous claims of high amplification ratios. For example, for annular air amplifiers, the maximum practical ratio you can achieve is about 20 to 1.
This means that if you measure the flow at the exit of an annular Air Amplifier, the flow rate would be 20 times the inlet air. For several reasons, some producers are claiming as much as 25 times, which is dubious. One reason is that when surrounding air is entrained with the moving compressed air exiting the opening in the Air Amplifier, “still” outside air will slow down the flow velocity at the outlet.
If you entrain, for example, 25 times the compressed air consumed, the velocity would be 20% less than it would be if the figure were only 20 times. That is significant because you need adequate velocity for both blow-off and cooling. Secondly, the explanations one can read on how this extra air amplification occurs should be challenged as defying physics.
In comparison, Nex Flow has done with such products, the results were a lower air amplification and even lower overall performance because of internal design and extra pressure losses internal to those systems. Anyone can always compare a Nex Flow Air Amplifier to another and see the difference. Nex Flow fixed Air Amplifiers, for example, claim 16 times amplification with a compressed air supply at 80 PSIG (5.5 bar) pressure and at standard atmospheric conditions.
These figures are averages because air amplification will go up (as much as 20) at lower inlet air pressure and if the atmospheric air is warm.
Air knives are another area where figures need to be considered between manufacturers. Air knives are linear air amplifiers. There are two styles of compressed air-operated air knives on the market. The older style uses several Coanda angles where the air exits a gap, normally maintained using a shim to set the gap, and is bent 90 degrees.
This gives a decent air amplification ratio of about 10:1 right at the exit and 25:1 to 30:1 measured 6 inches away (due to downstream air entrainment) depending on internal design effects. Some manufacturers have air knives with two gaps and claim as much of a 50:1 amplification ratio (two gaps, so they double the ratio) which makes dubious sense. You don’t double the air out and the ratio – it does not make sense to have it “additive.”
So again, it is good to challenge claims that may seem to make sense. Another thing to consider, especially with air knives, is real efficiency. Efficiency, as before, is the force measured at a distance per unit of air consumption, for example, force/SCFM. Internal design can make a difference. Newer style air knives have the airflow exiting straight out of the gap with air entrainment from special angles on each side of the air gap.
This design will provide 25% more force/SCFM than the older style versions, where the air bends 90 degrees. Hence their popularity has largely displaced the older style, but there are still some applications where the old style is useful. But even among the new style, design differences can affect performance and efficiency.
Nex Flow, for example, with their Silent X-Stream Air Blade air knife has a different internal design than two other significant air knife manufacturers and has about the same force/SCFM as them at a given pressure except for one thing… Nex Flow produces the same SCFM and same force at 60 PSIG, while the other units get equal performance and efficiency at 80 PSIG. That means a Nex Flow air knife needs less pressure to do the same job as the others.
It was quite humorous when one manufacturer claimed in a blog that our air knives used so much more air at a given pressure, but without mentioning the force produced, a poorly written defense of the fact that they are less efficient.
If the Nex Flow unit replaced the competitive unit, the air pressure could be reduced by 20 PSIG. As mentioned earlier in this article, that pressure reduction represents a 10% energy saving. So when comparing products, it is very important to look at all the facts. One of the other aspects of the Nex Flow Silent X-stream Air Blade air knife that dramatically illustrates efficiency is how quiet it is, even compared to other designs of its type.
One other point to mention is the flow profile. When an air nozzle, air jet, air amplifier, or air knife produces the amplified airflow, the profile will affect the force per square inch or square millimeter. This is particularly important in air nozzles. You need to decide on the minimum force required and the surface area you need to address.
This is especially important if putting together a row of nozzles for blow-off. You want the flow profiles to cover the required area without missing any spots or overlapping. A wider profile produces less force per unit area than a more focused air nozzle.
Air amplification is free, but among different designs, it can be more or less free than others. Besides reducing energy and noise, it is important to remember that air-amplifying products work at a greater distance than just open pipe or tubing.
The velocity produced by air amplification products is very important when used for cooling. The high velocity combined with the high flow is important, but they are mutually dependent. The more flow, the less velocity. The less velocity, the more flow. If the velocity is too low, you will not get the same cooling effect. Think of driving a car on a hot day with the window down.
It’s the same volume of air coming in to cool you, but the velocity from driving fast helps cool you more. But most certainly, air-amplifying products reduce energy use, and noise levels and make factory operations using compressed air more environmentally friendly.
Hollywood Special Effects with Nex Flow® Compressed Air Accessories
Not only have Nex Flow® products been used for Hollywood special effects for US made movies but also for movies made by other jurisdictions and for special effects in museums and in theme parks.
The most popular products used are the air knives and the air amplifiers for creating special effects where wind or heavy air flow needs to be simulated. The advantage of the Nex Flow air knife design is its high efficiency in being able to produce more flow and force at a lower pressure than competitive units (performs the same at 60 PSIG compared to competitors operating at 80 PSIG). The Nex Flow Fixed Air Amplifiers as well as more efficient than competitive designs by about 10% and are much more rugged for easier handling and use.
One unique application in a Stephen King movie was the use of a standard air knife which operates by having the compressed air exit the air knife, and bending 90 degrees over a series of angles. When aiming a flame source against the flow, the air bends the flame also 90 degrees. With some computer manipulation this simulated a barrier against a flame (bending it 90 degrees).
One of my favorite application is from the original X-files series filmed in Canada. The fixed air amplifiers were used to simulate heavy air flow as one of the characters (Mulder) in the X-files was taken by aliens from an airplane. That was simulated by using several AM125 units (now the part number has been changed to FX125).
Standard air knives (Model 10024 – 24” long units) have been used in the Keanu Reeves remake of The Day The Earth Stood Still. If you have seen the movie there are several scenes where the grass is rustling from the wind. This effect was created using the air knives. Because of its even air flow it made a realistic simulation of wind blowing over a large area that was filmed.
Product has been used even off camera. In one of the James Bond movies (the most recent James Bond with Daniel Craig) there is a scene where there is a sand storm and the cameras that were doing the filming had protected the camera lenses with air knives that acted as a barrier to prevent the sand from hitting the lenses.
We do not always know what the specific application is for the product. Several 2” Fixed Air Amplifiers were purchased by a special effect company in Brazil but we were not told of the scene. In 2018 some products were purchased for apparently a major superhero movie but we were advised that we could not disclose the details. Needless to say, I will be viewing all the superhero movies for clues on where the products might be applied! While it might not be as exciting as appearing in a movie, having your product in a movie is kinda cool!
It’s not only movies that use Nex Flow products. A large number of 4” Air Amplifiers were purchased a few years back by Universal Studios when revamping their special effect “wind from King Kong’s breathing” at their King Kong ride. They replaced product previously supplied by a competitor with the superior and better priced Nex Flow product.
Museums are also trying to have exhibit that are more interactive. One such museum approached Nex Flow to use a small air amplifier or air jet to simulating the effect of bats flying by people in one of their bats tunnel. The advantage of using the Nex Flow compressed air amplification technology is the portability, ease of use and also the quiet non-disturbing operation of the products. The compressed air is supplied by a compressor in the film studio or from a rented portable compressor when filming on site.
Ring Vac® air operated conveyors were also used by one special effect company but in this case we were not advised of the special effect. We suspect it may have been used to simulate the firing of a projectile of some sort.
Regardless of the particular special effect, there are many uses for compressed air accessories in the entertainment industry, whether for films, television, theme parks or interactive displays in museums. The application of Nex FlowTM compressed air products for blowing or conveying is limited only to the imagination. The low cost, compact nature, portability, and low noise level of the products make them attractive to use in creating special effects.
To choose the perfect blow off product for your manufacturing environment it is important to consider the application, placement in the factory, energy savings, health and safety, and finally material durability.
Application
One of the primary criteria for deciding which blow off product is right for your manufacturing plant is the application desired. This section describes the primary application for the following devices: air amplifier, air jet, air blade air knives, and air guns.
An air amplifier is an air mover that is virtually maintenance free. The primary applications of air amplifiers include cooling, venting exhaust, drying, cleaning, distributing heat in molds or ovens, and collecting dust.
Air Jets entrain large volumes of surrounding air. They are similar to air amplifiers but comes in a smaller size yet are more efficient flow amplifiers than nozzles. These jets cover a larger blow off area than a nozzle and are ideal for part ejection. They are primarily used for cooling, part drying, chip removal, and air assist.
Air BladeTM Air Knives consist of a body with a plenum chamber, cap, and either a machined gap in the body or a shim to maintain an even gap along the length of the air knife. It uses compressed air for industrial blow off and cooling. The laminar sheet of air created by the unit is often used to replace rows of nozzles or jets to reduce energy costs. Air Knife is most commonly used to dry, clean, and cool. Examples of applications include removal of liquid, dust, and excess oils from flat and curved surfaces, conveyor cleaning, blow off before painting surfaces, and scrap removal.
Unlike any of the above units, air guns are not integrated into the factory line but instead are handheld units for blowing off work surfaces and other applications that require a high force or flow application. Safety blow guns are used to blow off metal chips during drilling operations, removing “stuck” material such as tape, gasket material, caulk, adhesive, paint, and labels. With the addition of air, the detached material is blown away during scraping, keeping the area clean.
Location
Although these pressurized air equipment may be ideal for specific applications, they are sometimes interchangeably used based on space availability, desired orientation, and even the factory environment. It is important to keep in mind that these blow off devices must have room for exhaust. Furthermore, if the device is used by a worker, comfortability and ease of maneuver is key.
The shape and size of the unit are important considerations. Air amplifiers and jets are both circular products but jets are smaller in size than amplifiers. Hence the amplifiers can blow off a larger area but with less force than a jet.
Air knives are straight and vary in lengths anywhere between 3” to 36” and can be used as part of an automated conveyor system. Air guns, on the other hand, are typically used at work stations. Extensions and swivels of various lengths and gun tips (i.e. nozzle and air edger) are available, making the safety gun a very flexible handheld unit.
Energy Savings
Depending on the required application, finding the best fitting blow off product allows the equipment to do the same job at less pressure. Energy savings is accomplished by finding blow off products that have the highest force/air consumption ratio. Reducing compressed air use and noise levels translates into an efficient high output air with lower energy use.
Here at Nex FlowTM – we continuously research and design better engineered products for our customers. For instance – our standard air blades have been proven to reduce energy by 30% – 90% as it is designed to produce the most force over the length at the lowest possible input pressure. Taking it a step further – our silent air knives are designed to further reduce energy lost as noise and is 25% more efficient than the standard design.
The best blow off customized product and technical support is obtained by choosing Nex Flow systems. During installation, our highly trained customer technical support advises our customers to install equipment that provides the most accurate blowing angles and direction All Nex Flow compressed air blow off products have a five-year warranty against manufacturer’s defects.
Health and Safety
The most important reason to use Nex Flow® blow off equipment is safety. Air equipment exhaust can be loud. Noise and vibration that are detected by the human ear are classified as sound. “Noise” is the term to describe unwanted sound. Extended exposure to unwanted sound or at high levels can harm workers and can result in profound hearing loss. Hearing loss can also occur as the result of one-time repeated contact to loud sounds or uncomfortable sound pressure over an extended period.
Occupational Safety and Health Administration (OSHA) sets legal limits on noise exposure in the workplace. Guidelines are available that describe permittable duration of exposure for occupational exposure limits (OELs) for various noise levels. These OELs are determined using a weighted average over an 8-hour work day. With unnecessary noise, all workers should be exposed to OSHA’s permissible exposure limit (PEL) of 90 dBA during an 8-hour work day. Note: The OSHA standard uses a 5-dBA exchange rate.
Nex Flow takes noise levels into consideration very seriously because we understand that reducing noise levels from very loud and damaging compressed air equipment is important. Noise levels are much lower when using air nozzles and air jets. The added bonus is that the use of air nozzles and air jets, not only lower noise levels but also lowers energy use.
All Nex Flow blow off products provide noise reduction in factories to ensure the safety of your workers in a factory environment.
Some Air Gun suppliers do not provide energy effectivenozzles or are not safe to use. All Nex Flow® air guns are safe to use, have energy efficient nozzles, and meet OSHA guidelines for safety.
Reducing unwanted noise can be achieved through using noise-canceling headphones, mufflers on any exhausting air, or by adding low-cost air amplifying nozzles on blow off devices. To further enhance safety in the manufacturing environment, Nex Flow® monitoring devices can detect sources of noise previously missed or unidentified. Use the Nex Flow Digital Sound Level Meter to accurately monitor noise levels and ensure that high levels of sounds do not exceed OSHA limited standard 29 CFR – 1910.95 (a) which limits an 8-hour exposure of constant noise to 90 dBA. The maximum hold setting will provide the highest noise level and will update continuously if a higher noise level comes into play. If you need to keep a record of sound measurements, a complete data logging system is available.
All of Nex Flow blow off equipment provides noise reduction, meets OSHA safety standards, and are safe to use in any factory environment.
Material Durability
Compressed air operated equipment is generally simple to use, compact, rugged, and portable.
To keep our products durable – we do not use plastic shims to save costs like other manufacturers. Nex FlowTM only uses stainless steel shims to guarantee longer life with still very competitive prices.
It is also important to choose the correct material used to construct the accessories. In a high temperature and corrosive environment, 303/304 Stainless Steel is recommended. The 316L Stainless Steel is recommended for very corrosive or high temperature applications and when the application is food or pharmaceutical grade. Anodized Aluminum is usually suitable for most other application but for oily environment it may be worth choosing the hard-anodized aluminum. Learn more about “Why we do what we do with our materials” here (Link to article).
Nex Flow is the best supplier of blow off products. Our trained customer service and installation technicians can help you identify the criteria that is most important for your blow off application. Educating your workers, while performing regular inspections will enhance their work environment, prevent leaks, and extend the life of your blow off equipment. When choosing the best blow off solution, understanding the benefits of a well-engineered Air Knife, Air Amplifier, Air Jet, and Air Guns to withstand a harsh factory environment with safety in mind is important. Remember Nex Flow is happy to help you and your company to meet all your compressed air needs.
Case Study: Nex Flow Air Knife Making Chicken Nuggets and Delicious Muffins
Making muffins, or any mass food production operation has critical standards of quality that must be met. If cooking or baking is involved the heat needs to be precise and consistent. Similarly for the ingredients involved in the cooking or baking process.
Nex Flow Air Knives (also called Air Blades) are used extensively to replace drilled pipe or rows of nozzles and jets for blow off, drying and even cooling. As they are compressed air operated the flow rate and blow off force produced can easily and accurately be controlled for any of the applications.
This accurate control with compressed air operated air knives was especially useful in an interesting and unique application involving the baking of muffins that was installed some years ago. The muffins are produced continuously and then placed evenly spaced in rows onto a conveyor. As the muffins move along the conveyor sugar is added onto the tops of each of the muffins before they enter an oven. The conveyor is continually moving. The nature of the process of adding the sugar caused occasionally too much sugar to be applied to some of the products. As the muffins moved through the oven, the oversupply of sugar would create burnt tops or overly baked tops which were out of specification and had to be disposed of. While they may have been rejected I am sure some would have been disposed of by eager, and hungry personnel on the line in a very humane manner) The operation I must admit, was very pleasant to the smell and I remember it to this day! To prevent burnt tops – a mechanism had to be put in place to limit the amount of sugar on the muffins.
The means to remove excess sugar was achieved by using a stainless steel air knife at very low compressed air pressure. Very little energy was required to remove the excess sugar and it had to be finely tuned so that just the right amount of sugar was removed. The result is a perfect muffin every time. Yummy!!! The air knife needed to have a high quality in control of manufacture to produce the even flow required with low pressure across the length of the web to cover all the muffins. It also had to be in stainless steel as it is being applied in a food processing plant. Since Nex Flow air knives have this necessary high quality control, so no issues arise in this kind of application.
A similar food processing application came up years later at a factory making chicken nuggets. In this operation the company had previously used blowers to remove access breading on the nuggets. The reason is in the same vein – too much breading on the nuggets produces product that is out of specification. The blowers worked fine but very high maintenance is required. This is because the environment had to be cold for processing meat products and heavy wash downs of equipment must be done daily – thus creating this high maintenance environment for blowers. So instead, the plant switched over to using our stainless steel X-stream Air Blade air knives at very low pressure to remove the excess breading. As was with the muffins, it was all done on moving conveyors. Not only did the compressed air operated air knives perform the job well, it virtually needed no maintenance decreasing quite a bit of the cost. Because the pressure used was only around 10 PSIG for the blow off of excess breading the energy cost increase compared to what was used with the blowers was negligible. Another benefit was the very quiet operation of the air knife. At 80 PSIG the exhaust air noise level from the air knife is only 69 dBA and at 10 PSIG the sound was barely audible. The savings in maintenance cost, downtime, and personnel time for outweighed the slight increase in energy costs. Years of maintenance free, reliable product is assured with the use of the silent X-Stream Air Blade air knife. The much smaller footprint of the compressed air device replaced the bulky and noisy blower, creating more space and a better working environment for the employees.
In both operations and outlined above, it is important to have clean and dry compressed air. As compressed air makes contact with the food product in both of the above application – strict guidelines must be followed to ensure that the compressed air is free from contaminants with potential health hazards.
The reasons for choosing the compressed air operated air knives in both situations were similar:
First, it was used to improve the quality of the end product and the solution had to be tightly controlled (not too much, not too little). The compressed air solution allowed that to be done with the use of a simple regulator to set the optimum pressure.
Second, a simple and quick relatively low cost solution was required. In the muffin case, just the capital cost involved in getting a blower system would take a long time to get equipment approval, in addition to space considerations. As for the nuggets, the benefit of reduced maintenance and downtime alone, regardless of the extra benefits of less noise and more space was enough to justify the solution.
Third, easy installation, low noise, small footprint, and ease of use with near zero maintenance made the solution. In many processes you can still see open pipe and open air lines being used for drying, cooling, cleaning and moving products, but with very little investment, the process can be improved dramatically using the compressed air technology. Replacing open pipe, tubing, or drilled pipe using compressed air with the appropriate nozzle type from Nex Flow can reduce noise levels by 10 dBA or more. It can improve safety and improve the manufacturing process with paybacks in energy use in less than a year. When replacing blower systems, the maintenance costs should also be weighed in along with assessing the actual pressures used in the process. Another factor to consider is whether the blow off, cleaning, drying, cooling or moving of part is intermittent. A compressed air solution allows for an on/off switch, wherein blowers system have to be on all the time. This means that compressed air can be used “on demand” to further save energy.
Contact one of our personnel, so we can help assess your application to determine the best approach to improving your operations, in all sorts of industries that involve the use of compressed air. Our goal is to make sure that compressed air is used in the most optimum, most productive, and the safest way in a factory environment.
Have you ever heard someone said something along the lines of “well that’s definitely a powerful machine – just listen to how loud it is”. While this may be true some of the time it is not always the case. When working with compressed air, having a well-designed machines and accessory that is equally powerful at a much lower noise level is always a plus. Here are some things to consider about noise.
Loud Noise Means Less Efficiency
Have you ever tried to concentrate with loud noise? It is much more difficult to think clearly with loud noise. But it’s not just personal efficiency that can be negatively affected, the efficiency of the device making the noise can also be jeopardized. For instance, the noise involved with compressed air blow-off can mean a leakage or an inefficient design. It is still prevalent to use open tubes and jets and drilled pipe for blowing compressed air in production applications to clean, cool and move products. However, the exhaust noise using these methods can exceed 90 dBA depending on the pressure used and the bulk of the noise generated by this method of blowing with compressed air is from the energy lost as it exits the tube or pipe. In other words, the energy is loss as noise and pressure drop because the flow and force from dilled pipes and open tubes are mostly turbulent.
Turbulent Flow can be characterized as having tiny whirlpool regions and it also increases the amount of air resistance which is useful for accelerating heat conduction and thermal mixing. However, it is not useful for blowing applications. Turbulent flow will produce a great deal more noise. For blowing with compressed air, whether for cooling or cleaning or drying, laminar air flow is preferred.
Laminar Flow is when the flow of a fluid (in this case, air) follows a smooth path, or paths which never interfere with one another. One result of laminar flow is that the velocity of the fluid is constant at any point in the fluid movement path.
Just how much can noise be reduced and how much energy saved using blow off products that produce a laminar flow? The answer is – quite dramatic. A laminar flow nozzle can reduce noise levels as much as 10 dBA and reduce energy consumption by 30% – 40%. Likewise, laminar flow air knives which is basically long, flat nozzles are used to replace drilled pipe for higher efficiency. Some designs are extremely quiet and can reduce exhaust air noise to as low as 69 dBA.
High Noise Level is a Hazard
Of the roughly 40 million Americans suffering from hearing loss, 10 million can be attributed to noise-induced hearing loss (NIHL). NIHL can be caused by a one-time exposure to loud sound as well as by repeated exposure to sounds at various loudness levels over an extended period of time.
Sound pressure is measured in decibels (dB). The average person can hear sounds down to about 0 dB, the level of rustling leaves. A handful of people with very good hearing can hear sounds down to -15 dB. On the other end of the gauge, a sound that reaches 85 dB or stronger can cause permanent damage to your hearing even if exposed for a very short time. The timespan you listen to a sound affects how much damage it can cause. The quieter the sound, the longer you can listen to it safely. A very quiet sound will not cause damage even if you listen to it for a very long time. However, a sound that reaches 85 dB can cause enough damage to induce permanent hearing loss. Here are some common sounds.
A typical conversation occurs at 60 dB – not enough to cause damage.
A bulldozer that is only idling (not actively bulldozing) is loud enough at 85 dB – after only 8 hours it can cause permanent ear damage.
When listening to music – a stock earphones at maximum volume can generate sounds reaching a level of over 100 dBA. Loud enough to begin causing permanent damage after just 15 minutes a day!
A clap of thunder from a nearby storm (120 dB) or a gunshot (140-190 dB, depending on weapon), can both cause immediate damage.
It is estimated that as many as 30 million Americans are exposed to potentially harmful sounds at work. Even outside of work, many people participate in recreational activities that exposes them to harmful noise (i.e. musical concerts, use of power tools, etc.).
Designing the Future of Air Blow Off Technology
Nex Flow® Air Products Corp. continually perform and fund research to constantly improve the efficiency and safety of compressed air accessories. With this approach, we are able to offer noise reduction for compressed air technologies that are equally or more efficient than competitive units.
Air Nozzles
Our Air Nozzles are engineered to reduce noise by 10 dBA over open pipe, tube or jets and maximize laminar flow to increase force/compressed air consumed.
One of the oldest styles of air saving, noise reducing air nozzles are of a cone shaped design. But if you put every single design next to one another both energy saving and noise reduction will vary greatly because many times the aerodynamic design is neglected. Having the nozzle outside appearance as a cone shape in not enough. There are many other (proprietary) factors to consider to truly minimize turbulence and maximize laminar flow. The cone shaped designs are still the optimum style to use for maximizing total volume of flow produced per quantity of compressed air consumed and is especially ideal for cooling applications. Where cost is a factor, this model is ideal.
The Air Mag is another one of our engineered nozzle with patented design. The bullet shaped design trumps the cone shaped design for producing the highest force/quantity of compressed air consumed. The patented design allows the Air Mag to provide the furthest distance for laminar flow compared to competitive units. Other bullet shaped nozzles need to be close to the target as turbulent flow begins to occur after only a short distance from the nozzle. Our unique design helps significantly extend the range of the laminar flow. Due to increased complexity and manufacturing processes, they are more costly than the cone shaped designs. However, they are the best option for when force produced is an important factor.
Air Knives
When replacing drilled pipe with holes, the Nex Flow Silent X-stream Air Blade air knife lives up to its name. At 80 PSIG the unit is runs on just 69 dBA exhaust noise and uses the same air consumption as if running competitive units at 60PSIG. Extremely popular as they often replace competitive units in the field because of the design and quality of manufacture.
Other blow off products we offer include air flow amplifiers, air jets, and many more. Our accessories are used not only for blow off and cooling applications but can also be used for conveying, cleaning and to control static electricity.
The next time you hear a loud sound when using compressed air anywhere in the production line, don’t forget to check and see what is making that noise. Loud noise is a health hazard and is often wasted energy. So, if the source of the noise is coming from an open tube, open pipe or a drilled pipe of any sort, chances are, you can reduce this noise very quickly and even reduce energy and get better performance by using low cost products from Nex Flow®.
Compressed Air: 5 Associated Injuries and How to Stay Safe
While compressed air is relatively safe compared to many other sources of power, especially electricity, there are still safety issues that need to be considered with using compressed air. Here Nex Flow shares 5 injuries associated with compressed air operations and how to steer clear of them.
1. The Eyes
The most common injury from the use of compressed air is to the eyes. Compressed air is used by most industries and is often used to blow off and clean work places of dirt and debris. A prominent cause of eye injury is when chips and particles bounce back towards the operator when blowing off or working. This is often not stressed enough, but it can be a huge safety risk as the eyes are one vital way for us to sense the environment. Even the smallest of particle has the potential to cause a large injury, especially if correct safety equipment is not readily accessible. As little as 12 pounds of compressed air pressure can blow an eye out of its socket.
According to the United States Occupational Safety and Health Administration (OSHA), up to 90 percent of eye injuries can be prevented with correct safety equipment. When flying chips and particles is part of the work environment, wear safety glasses with side protections. These help to prevent back bouncing particles from getting in behind the safety glasses and cause harm.
Three important things to think about to decrease the risk of eye injuries:
Work preventively by understanding the nature of the work assigned and minimize the risk of harm
Identify and eliminate potential risks before diving straight to work. Remember that work screens and other guarding equipment can be used to limit risk area.
Use proper safety equipment that protects the eyes.
To work without safety in mind in an environment where eye injuries can occur can be very expensive. The annual cost of eye in juries is estimated to be over $300 million per year. To increase safety, and extra protection when blowing off, air guns with safety shields can be used to minimize the risk of chips and particle that can be blown behind safety glasses and cause potential injury.
2. The Ears
Compressed air noise can cause damage to the ears. Compressed air exhaust noise can be quite noisy when used for blow off or cooling. Blowing with compressed air can result in elevated noise levels that can be harmful to both the operator as well as the surrounding persons. Both short and repeated blowing operations can be harmful and result in hearing damage and tinnitus. The damage can appear gradually, and it can be difficult to determine when and how the hearing problems developed. OSHA’s regulations also affect the approved noise level of a workplace. Open jets and pipe can produce noise levels as high as 90 dBA or more which is very dangerous to hearing even with short term exposure. Learn more about noise levels here. In any factory environment, there are certainly many other sources of noise from moving machinery, grinding of gears, the squeaking and clanging of chains, and banging of parts. Damage from compressed air noise can have serious and damaging effect on your hearing due to high noise exhaust levels. Fortunately compressed air exhaust noise can be addressed by the use of exhaust mufflers on devices such as air cylinders and the use of engineered air nozzles, compressed air amplifiers, and air knives to reduce the noise levels significantly.
3. The Skin and Body
Skin and body damage can also occur from flying debris when using compressed air for blow off or cooling. Blowing to cool a hot part can cause a chip or hot dirt particle to become loose and possibly fly towards and burn your hands and arms. Even small particles can bounce back and at high enough velocity can embed into the skin and cause infection later on, even if not felt immediately. Again not only is the use of eye shields important but it is equally important to wear protective clothing when handling compressed air in a high risk environment. Compressed air accidentally blown into the mouth can rupture the lungs, stomach or intestines. Even with a layer of clothing, compressed air can enter through the navel so be cautious and pay attention to your surroundings when in an industrial environment. It also helps to know and abide by compressed air safety standards.
A very serious situation occurs when compressed air enters the bloodstream – an aeroembolism. This can happen if the operator is blowing compressed air on themselves or someone else. If the pressure becomes too great or the compressed air is blown directly against the body, the compressed air can get underneath the skin and into the bloodstream.
Compressed air is a concentrated stream of air at high pressure and high speed that can cause serious injury to the operator and the people around him. First, compressed air in itself is a serious hazard. It has been known for compressed air to enter the blood stream through a break in the skin or through a body opening. An air bubble in the blood stream is known medically as an embolism, a dangerous medical condition in which a blood vessel is blocked, in this case, by an air bubble.
An embolism of an artery can cause coma, paralysis or death depending upon its size, duration and location. While air embolisms are usually associated with incorrect scuba-diving procedures, they are possible with compressed air due to high pressures. This may all seem to be improbable, but the consequences of even a small quantity of air or other gas in the blood can quickly be fatal so it needs to be taken seriously. Unfortunately, horseplay has been a cause of some serious workplace accidents caused by individuals not aware of the hazards of compressed air and/or proper work procedures. If an air pocket reaches the heart, it causes symptoms similar to a heart attack. Upon reaching the brain, pockets of air may lead to a stroke. Therefore to stay safe, do not use pressurized air to blow on yourself and other personnel, and avoid horseplay when working with compressed air.
5. Faulty Equipment
Another danger to be aware of when using compressed air is with hoses and quick disconnects. Leaking or damaged hose or connectors can be quite dangerous as they could break. Under pressure broken hoses or hoses that come loose from the system because of failed connectors can whip around and cause serious injury. If people are working with old or frayed hoses, air may leak out causing a pressure drop. This lack of pressure can cause machines to malfunction and other problems. If the hose is damaged and then pressurized it could cause injury when it ‘explodes’ outward. This sudden release of the pressure can cause a machine to engage or disengage, resulting in injuries to the operator and bystanders.
To stay safe, check the hoses regularly and never – of course – use frayed, damaged or deteriorated hoses. Worn connectors and hoses should be replaced immediately. Store hoses safely, away from heat and sunlight to prolong the product lifetime. Hoses are best stored on a hose reel for longer life, and to avoid tripping hazards.
Compressed air is still one of the safest and friendly utility to use with many advantages. But while relatively safe, certain precautions as listed above are still necessary so you can safely enjoy the benefits of compressed air.
The Coandă effect is the tendency of a stream of fluid (air or liquid) coming from an opening to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops. It can also be described as the tendency of a fluid to adhere to the walls of a convex surface.
Commonly a free jet of fluid entrains and mixes with its surroundings as it flows away from a nozzle. The key to the Coandă effect is that when the jet of air comes close to a curved surface, it remains close to the curvature even if the surface is curved away from the initial direction of the jet of fluid. This effect can be used to change a stream’s direction. In doing so, the rate at which the jet mixes are often significantly increased compared with that of an equivalent free jet.
When the fluid increases in speed, the pressure decreases, and this pressure imbalance results in the flow being pushed against the surface by the atmosphere. This means that even if the surface curves away from the direction of flow, the flow keeps sticking to it because the atmosphere is “applying” pressure so the liquid sticks to the surface. This continues until the flow slows down and mixes with ambient air taking away the pressure difference.
This effect is quite widespread in its applications – from airplanes to windshield washers in automobiles and even in air conditioning unit designs and their placement.
Bernoulli Principle and Coandă effect: Their Contributions to Flight
Daniel Bernoulli (1700-1782) discovered an effect named after himself over 300 years ago called the Bernoulli’s Principle. Air behaves like a liquid and when air moves, the pressure around the air parcel decreases. He discovered that if you can move air along a surface, the pressure on that side of the surface will be less than the pressure on its other side. This principal is used to lift airplane wings on aircraft.
The Bernoulli principle describes how planes fly. Aircraft wings have curved top sides and the bottoms are relatively flat. When moving, air hits the front edge of the wing causing some of the air to move up over the wings and the rest to move below the wing. As the upward movingair must follow the curvature of the wing and travels further than theair moving under the wing to reach the back edge at the same time, the air pressure on the top of the wing is reduced according to Bernoulli’s principle. The resulting higher pressure under the wing, lifts the aircraft. This lifting effect pushes the wing upwards and keeps the aircraft in flight.
Though Bernoulli’s principle is a major source of lift in an aircraft wing, a Romanian aerodynamics pioneer engineer, Henri Coandă (1885-1972), discovered another effect that also helps produce lift. Henri Coandă, built the first jet aircraft in December 16, 1910 with his partner Gianni Caponi (another aviator). The plane, called the Coandă-1910, was a 4-cylinder piston engine used to power a rotary compressor. It was displayed in Paris at the Second International Aeronautical Exhibition and, unlike all other planes at the time, the Coandă-1910 did not have a propeller. The motor-driven turbine of his specially designed aircraft sucked the air through the turbine, while the exhaust exited from the rear. This design drove the plane forward by propulsion. Coandă noticed that the airflow was attracted to nearby surfaces. In 1934, Coandă obtained a patent in France for a “method and apparatus for deviation of a fluid into another fluid.” The effect was described as the “deviation of a plain jet of a fluid that penetrates another fluid in the vicinity of a convex wall.” The first official documents that explicitly mention the Coandă effect were two 1936 patents by Henri Coandă. (Coandă effect, Retrieved from Wikipedia on Dec 12, 2018). Unfortunately, the first flight ended in an accident and he could not raise enough money to continue his research. “A moving stream of fluid, when in contact with a curved surface, will tend to follow the curvature instead of continuing to move in a straight line.”
Like the Bernoulli effect, the Coandă effect also describes how an airplane’s wing lifts. The difference is the Coandă effect describes the angle of attack, which is the angle between the wing and the direction of the air flow, as shown in the following diagram:
The angle of attack indicates the wing’s tilt with respect to the oncoming air. To lift the wing, Newton’s third law says that there must be an equal force acting in the opposite direction. If we can exert a force on the air so that it is directed down, the air will exert an upward force back on the wing. As the angle of attack increases, so does the lift. If the angle of attack is too great, the air flow will stop following the curve of the wing and a small vacuum is created behind the wing causing vibration and decreases the wing’s efficiency. The wing’s efficiency is important because it directs the airflow downward and pushes up on the wing to produce lift. If the surface is not too sharply curved, the jet of air can follow the surface. The forces that cause these changes in the direction of flow causes an equal and opposite force on the surface along which the jet/stream flows.These Coandă effect/forces causes lift depending on the orientation of the jet and the surface to which the jet/stream adheres. This effect can be induced in any fluids including water.
Applications of Coandă effect in Compressed Air Industries
Henri Coandă was the first person to recognize the practical application of the phenomenon in aircraft development. The effect is used to power pneumatic production equipment, air operated lathe chucks, pressure clean parts, and to convey or cool components during production for the following industries:
Chemicals
Pharmaceuticals (i.e. ventilators)
Food & Beverage
Aeration and Agitation
Semiconductor & Electronics
Medical Breathing Air
Automotive for tires and breaks
Manufacturing
Compressed air is also used for maintenance, power washers, and other cleaning tools.
In air conditioning, the Coandă effect is exploited to increase the throw of a ceiling mounted diffuser. It cools without the use of chemicals. Because the effect causes air discharged from the diffuser to “stick” to the ceiling, it travels farther before dropping for the same discharge velocity than it would if the diffuser was mounted in free air, without the neighboring ceiling. Lower discharge velocity means lower noise levels and in the case of Variable Air Volume (VAV) air conditioning systems, permits greater turndown ratios. Linear diffusers and slot diffusers that present a greater length of contact with the ceiling exhibit a greater Coandă effect.
The Coandă effect is used in compressed air flow amplification technology to create energy efficient and noise reducing air amplifiers or movers, jets, and knives used in blow off applications. This effect helps to save energy and meet Occupational Safety and Health Administration (OSHA) standards in compressed industries.
Air Amplifiers or “Movers”
A compressed air flow amplifier works by entraining air along with compressed air. The amplified air utilizes the Coandă effect to draw in surrounding atmospheric air while consuming only a minimal amount of compressed air. These products can amplify airflow up to 17 times with reduced noise levels. The air follows the profile of a pipe outward to cool or dry a surface. Compressed air mixes with ambient air drawn into the device causing the resulting mixed air to have a higher flow and force than the starting ambient air. Air movers are more effective for cooling because of the high velocity outlet flow when compared to flat nozzles. The force produced for blow off decreases as the amplifier outlet diameter increases.
The increased flow reduces the amount of compressed air required. Allowing the Air Amplifier to be used in applications like venting fumes and smoke, conveying low weight materials, and entraining a high volume of air to cool, blow off, or dry.
Air Jets
Compressed air jets generate a high-volume air flow while minimizing compressed air consumption. The compressed air is distributed through an annular ring and is directed towards the outlet using the Coandă effect. This results in the entrainment of surrounding air and results in a great force and velocity compared to the minimized volume of compressed air needed.
Air Knife
Air knives use the Coandă effect for product cooking, drying, and cleaning. An air knife system can be found in most manufacturing and packaging plants such as:
Food packaging for drying; cooling; removing spills from packaging materials
Bottle plants for drying cans and bottles
Metal forming for cleaning; cooling; galvanizing; roll forming
Foundries and casting plants for cleaning and cooling
For example:
The coating thickness in hot-dip zinc galvanizing process is often done using the gas wiping through an air knife system that uses the Coandă effect. The thickness of the galvanized zinc is of practical importance in determining the quality of product.Such a gas wiping method causes a technical problem of splashing from the strip edge to have a harmful effect on the performance of the galvanizing process and the product quality. The results obtained from “a study on the air knife flow with Coandă effect” Journal of Mechanical Science and Technology 21(12):2214-2220, December 2007, show that Coandă air knife system (nozzle)effectively reduces the splashing problem, leading to improvement of the whole galvanizing process.
Nex Flow Air Products Corp. specializes in the manufacturing of compressed air products for blow off, cooling and moving to optimize energy use and safety.
Recommended compressed air standards and related terms
There are several major standards to consider with the use of compressed air – two with regard to air quality, one for compressed air safety and any local standards related to noise.
Since compressed air is used in so many areas where it can come in contact with food or medicines, air quality standard is probably the most important standard related to compressed air use. ISO 8573, established in 1991 is a multi-part standard for compressed air quality to facilitate compressed air system component selection, design and measurement. Part 1 classifies contaminant type and assigning air quality levels, and Parts 2 through 9, define testing methods to accurately measure a full range of contaminants within the end user’s facility. The ISO 8573 Air Quality standard does not however address how manufacturers are to test and rate the filters. The ISO 12500 filter standard was developed to address this issue and establishes how manufacturers test and rate compressed air filters by defining critical performance parameters (namely, inlet oil challenge, inlet compressed air temperature and pressure measurement techniques) that will deliver certifiable filter performance information suitable for comparative purposes.
ISO 12500 is a multi-part standard, with ISO 12500-1 encompassing the testing of coalescing filters for oil aerosol removal performance, ISO 12500-2 quantifies vapor removal capacity of adsorption filters, and; ISO 12500-3 outlines requirements to test particulate filters for solid contaminant removal.
Occupational Safety and Health Administration (OSHA) standard 1910.242(b) requires that compressed air used for cleaning purposes must be reduced to less than 30 psig (pounds per square inch gauge, 204 kPa). Compressed air used for cleaning must only be permitted with effective chip guarding and personal protective equipment to protect the operator and other employees from the hazards of the release of compressed air and flying debris. Standard 1917.154, which addresses similar hazards in the maritime industry, explicitly prohibits the use of compressed air for personnel cleaning. While this particular requirement is not specifically applicable in the general industry setting, it is recognized as good practice for all industries. Standard CFR 1910.242(b) is a major guideline for Nex FlowTM in the design of their air saving nozzles, to keep dead end pressure under 30 psig.
Noise standards vary around the world. Compressed air, when exhausted from cylinders, air nozzles especially, produce noise – both impact noise and exhaust noise. Please refer to our article on noise levels for more detail.
Terminology used in compressed air systems can be confusing, so we have defined some for you along with common units and conversions below (the terms do not include terms related specifically to the compressors themselves – just terms downstream).
Absolute Pressure – The measure of pressure compared to the absolute zero pressure of an empty space—e.g., a vacuum. Expressed in pounds per square inch (PSI) or bar (BAR) or kilopascals (KPa). 1 bar equals 14.7 PSI equals 100 KPa
Actual Capacity – Also known as Free Air Delivered (FAD), this is the amount of gas actually compressed and delivered (at rated speeds and conditions) to a discharge system. Expressed as cubic feet per minute (CFM) or liters (LPM) per minute where 1 CFM = 28.32 LPM.
Air Consumption – The compressed air consumed from the compressed air system by any machine, air tool or blow off device to operate expressed at a particular input pressure to the device and usually in SCFM or SLPM as defined further below.
Amplification Ratio – A term typically used with blow off devices such as engineered air nozzles, jets, air amplifiers, air knives to express the amount of increase in air flow compared to the compressed air used. Should be expressed at a particular distance from the blow off device. It is usually and average over various inlet pressures.
Atmospheric Pressure – The measured surrounding pressure of a particular location and its altitude. Measured in PSI or BAR or KPa as explained above
Blow Off Force – The force produced by a blow off nozzle, jet, air knife or amplifier on pounds force or grams as a particular pressure at the device inlet, expressed at a particular distance from the device.
Free Air CFMor LPM– Air’s flow rate at a specified point and condition, which is then converted to surrounding conditions.
Actual CFM or LPM – Air’s flow rate at a specified point and condition.
Inlet CFM or LPM – Air that is flowing through the inlet filter or valve of a compressor (under rated conditions).
Standard CFM or LPM – The flow rate of free air that is measured and then converted to a uniform set of reference conditions. Normally expressed as SCFM or SLPM.
Dew Point – The temperature point at which moisture starts to condense in the air, if the air continues to be cooled at a single pressure.
Compressed air can be costly – so it is important to keep waste at a minimum while taking advantage of the benefits compressed air offers.
A good practice is to measure and monitor your compressed air system, flow rates, operating air pressure and energy consumption. Small adjustments where applicable can reduce your operating costs while improving flow rates and output. Here are 10 things that you can do now to optimize your systems and reduce energy costs!
1.When Not In Use, Turn Off the Compressed Air.
There are 168 hours in a week, but most compressed air systems only run at or near full capacity between 60-100 hours. So depending on your plant’s shift work pattern, you may consider turning off your compressors in the evenings and on weekends. This could reduce your energy bills up to 20 percent! One of the advantages of compressed air is that the energy can be used “on demand” so you can use it only when you need and not when you don’t. For example, if you are using compressed air for any blow off, drying or cooling application and the part being addressed is intermittent, you can install a sensor, PLC or timer and a solenoid valve to turn the compressor on and off as needed. Depending on how intermittently the air is needed, savings can easily add up from anywhere between 5% and 20%. This is an advantage of compressed air that is often overlooked – so when using compressed air, or considering its use against other options, don’t forget to keep the actual cycle time in mind because this can have dramatic impact on the actual costs. You cannot have this instant “demand” with most other options.
2.Find and Fix Existing Leaks in the System.
An air leak that is ¼” can cost you more than $2,500 a year. Imagine a series of smaller leaks that can potentially add up to sizes larger than ¼”. Pipe systems that are older than five years may have leaks of up to 25 percent of produced capacity if left unchecked and unrepaired. It takes energy to generate compressed air, so any air that leaks is essentially money wasted. Yet – air leaks tend to be largely ignored because you cannot “see it”. But if you have a water leak it is readily visible and often quickly addressed. Yet the cost of a compressed air leak can be much higher. Approximately 80 percent of air leaks are not audible so one means to detect (and then repair) leaks is to regularly check for leaks using a quality Ultrasonic Leak Detector. Many air leaks are from piping (especially at pipe joints), and from poor, inexpensive or worn out fittings, from valve assemblies and even from stuck auto drains used on filters. To minimize these problems, sometimes third-party is contracted to come into an operation to detect these leaks, assess their cost and the factory can then facilitate appropriate repairs or part replacements as necessary.
3.Prevention of New Leaks.
Benjamin Franklin once said, “An ounce of prevention is worth a pound of cure.” Check your piping system for its quality. A clean, dry pipe system indicates good quality compressed air and no corrosion issues. Dust in the pipe is caused by particles in the compressed air. If the air is not properly filtered, or if inlet filters are clogged, pressure drops will occur and the risk of end product contamination will increase. Sludge in the pipe is very bad news and should be addressed immediately. Dust and sludge in a compressed air piping system will cause corrosion very quickly and will greatly increase the number of leaks. Properly dried and filtered air keeps your pipe system clean and minimizes the occurrence of leaks. Be proactive in regularly checking for leaks in filters, fittings, valves, and connectors. Old quick disconnects are notorious for leaks. Use quality units and replace worn out units.
4.Reduce System Pressure if Possible. Run at required pressures – not more, for Each Application.
Every two PSIG reduction in compressed air pressure from the air compressor reduces energy consumption by one percent. When a system has issues there is a tendency to increase the supply pressure to compensate. Leaks cause pressure reduction downstream so resist the urge to turn up the pressure to compensate for leaks. Pressure drop is also caused by undersized piping delivering the compressed air to specific applications or by undersized fittings, and connections or from clogged filters. It is better to address the actual cause or causes of the pressure drop rather than simply increasing the supply pressure. A central supply side controller can reduce the operational pressure band and control air production more efficiently and effectively. Pressure regulators with gauges at appropriate locations can set the optimal pressure level needed for the particular application to minimize compressed air use and also indicate when access pressure drops occur.
5.Check Condensate Drains. Are your condensate drains stuck on open?
Condensate drains on timers are common items and there is a perception that they do not waste a great deal of compressed air. They should be adjusted periodically to ensure that they open as intended and that they do not get stuck in an open position. Concerning the perception that timer drains waste only a small amount of compressed air, it may be true in a small operation. However, if you have more than a few such units, that small cost can add up to a significant amount. It is better to replace timer drains with zero-loss drains to stop wasting compressed air. Such drains used to be expensive but have come down in cost significantly over the years and are now much more economical to use.
6.Review Your Piping Infrastructure to Optimize.
A piping system design should optimize transfer of compressed air at the desired flow and pressure to the point of use. Increasing the size of a pipe from two to three inches can reduce pressure drop up to 50 percent. Shortening the distance air has to travel can further reduce pressure drops by about 20-40 percent. Factory operations change over time. Machines are moved, added, or replaced. A look at the system pipe size and layout to determine how much compressed air is used in each section can provide an idea of whether the pipe is at the optimum size for current use. The more flow through a pipe the greater the pressure drop. The drop also increases with the square of the increase in flow, which means, if you double the flow, the pressure drop will increase four times. Air distribution piping diameter should be large enough to minimize pressure drop. If the piping is too small, it should either be replaced or a parallel line should be installed. Either option can address the issue.
7.Change Filters Systematically. Not only when they become so clogged that you must change or service them.
Inspect and replace or service filters systematically to ensure the quality of your air and prevent pressure drops. Over time, filters with replaceable cartridges will build up particulate on the cartridge and this increases pressure drop. In some cases indicators are available (pressure gauges before and after the filter also do this) to indicate the pressure drop across the unit. This goes beyond just the air compressor and the compressor room. All air-line and point-of-use filters within the facility should be checked and a regular cartridge replacement or filter cleaning schedule should be put in place depending on the type of filters. Those are just as important to maintain as the air compressor and air compressor room filters.
8.Utilize the Heat of Compression. Compressing air generates heat – Use it!
When compressing air it gives off heat, a lot of heat. As much as 90 percent of that heat can be recovered for use in your factory operations with heat exchanger technology. This wasted heat can be used to produce hot water for washrooms or to warm up and direct warmed air into a workspace, warehouse, loading dock, or entryway. The savings can be significant. This alone can justify using compressed air over other power sources if this waste heat has a useful purpose.
9.Follow Your Compressor Maintenance Schedule. Ignoring maintenance costs more.
You would not ignore a scheduled oil change on your car. The same reasoning applies here. As with most industrial machinery, in fact any machinery, a compressor runs more efficiently when properly maintained. Proper compressor maintenance cuts energy costs around one percent and helps prevent breakdowns that result in downtime and lost production. Maintain oil change schedules and other timely scheduled maintenance on your compressors. If you have several compressors consult your air compressor supplier on the most efficient way to have them set up to run and review the types of compressors best suitable for your current applications.
10.Use Directed Compressed Air More Effectively.
.About 70% of compressed air products (after leaks) is used for blow off and cooling. Inappropriate applications includes any application that can be done more effectively or more efficiently by other means than using compressed air such as blowers. That being said, however, compressed air is often used because of the velocity or force necessary for certain application that blowers cannot provide. At other times the cooling effect is desired where other options cannot do for any number of reasons, some being available space or lack of local support for another technology. Rather than demonize the use of compressed air, it can be applied very efficiently for blow off, drying and cleaning by using engineered parts like air nozzles, and other air “amplifiers” both annular type and linear or “air knife” versions that converts energy normally lost as pressure drop and noise into high velocity and high volume flow. This type of technology can reduce compressed air costs at point of use anywhere from 10% to 90% while maintaining production rate output and quality, something which is sometimes sacrificed when attempting to replace compressed air. Therefore it is wise to thoroughly consider the benefits and drawbacks of your options before making a decision.
So that’s 10 ways you can reduce and save up on compressed air use and energy for your plant. Don’t forget to think of the benefits and drawbacks when choosing a product for your specific application and be creative! Even heat that is normally considered a waste product can be utilized to save operation costs!
Compressed air amplification products have small air exit “gaps” and if not properly filtered can get dirty and block airflow. But there is an easy way to clean.
No matter how well your compressed air supply is filtered, at some point in time, there will be particulate buildup in the blow-off product used and the most common blow-off products ignored for this are air knives and air amplifiers.
These products operate using an air gap where the compressed air exits over aerodynamically designed surfaces to entrain surrounding air and convert pressure lost as pressure drop and noise into useful airflow. Over time deposits can build up over these surfaces which can negatively affect the entrainment and reduce the output airflow efficiency. Carefully wiping these surfaces can be easily achieved but wiping with care to avoid damage to these surfaces.
However, the problem of particulate buildup can be inside the plenum chambers of the air amplifier or air knife. In this case, it is more complicated. This problem manifests in uneven flow from the air amplifier or knife. This is detrimental to the production process because the cleaning or drying (and even cooling) application for the particular product can be less effective with this uneven flow.
If left too long, the device may need to be removed from production, disassembled, and cleaned if too clogged with dirt and debris. However, when the problem manifests itself with the uneven flow, an easy method to clean is described in the video where you simply keep the air flowing, but at a lower pressure for safety, loosen the body and cap, and blow out the particulate, then retighten,
Nex Flow Air Products Corp. has representatives worldwide to assist you in compressed air blow off, cooling, drying, cleaning and conveying.
