The EXAIRSuper Air Knife is the most efficient compressed air knife on the market. We know this because we’ve tested them, and our competitors’ offerings, for performance, using the same instruments, controls, and procedures. We’re not going to publish data that we can’t back up, and that’s a fact.
They’re also ideally suited to a wide variety of applications – they come in lengths from 3 inches to 9 feet long (and can actually be coupled together for uninterrupted air flows of even longer lengths,) a variety of materials for just about any environment. But the best thing about our Super Air Knives is how you can adjust the air pressure and flow to complete a wide variety of tasks. You can adjust them in two different ways, Replacing or adding Shims, or regulating the incoming air pressure.
Changing out your shim!
A larger shim gap will give you higher flow and force from your Air Knife. Honestly, the 0.002″ shim that comes pre-installed in all of our Air Knives is perfectly suitable for most blow off applications, and appropriate air supply conditions are the first thing you should check for before going with thicker shims, but if you do indeed need a boost, a thicker shim will indeed give you one…here’s a blog with the video to show you how it’s done:
Another advantage to having a Pressure Regulator at every point of use is the flexibility of making pressure adjustments to quickly change to varying production requirements. Not every application will require a strong blast sometimes a gentle breeze will accomplish the task. As an example one user of the EXAIR Super Air Knife employs it as an air curtain to prevent product contamination (strong blast) and another to dry different size parts (gentle breeze) coming down their conveyor. For Performance at different supply pressures see the chart below.
EXAIR products are highly engineered and are so efficient that they can be operated at lower pressures and still provide exceptional performance! This save’s you money considering compressed air on the average cost’s .25 cents per 1000 SCFM.
If you’d like to discuss altering the performance of your Super Air Knife, give us a call.
How do we know something is true? In grade school, you may remember being taught a process by which an observation elicits a question, from which a hypothesis can be derived, which leads to a prediction that can be tested, and proven…or not) These steps are commonly known as the Scientific Method, and they’ve been successfully used for thousands of years, by such legendary people of science as Aristotle (384 – 322 BC,) Roger Bacon (1219 – 1292,) Johannes Kepler (1571-1630,) Galileo Galilei (1564-1642) and right up to today’s scientists who run the CERN Large Hadron Collider. The collider is the largest machine in the world, and its very purpose is the testing and proving (or not) of hypotheses based on questions that come from observations (often made in the LHC itself) in ongoing efforts to answer amazingly complex questions regarding space, time, quantum mechanics, and general relativity.
The Scientific Method is actually the reason (more on this in a minute) for the name of a fundamental law of physics: Boyle’s Law. It states:
“For a fixed amount of an ideal gas kept at fixed temperature, pressure and volume are inversely proportional.”
And can be mathematically represented:
P = is the pressure of a gas
V = is the volume of that gas, and
k = is a constant
So, if “k” is held constant, no matter how pressure changes, volume will change in inverse proportion. Or, if volume changes, pressure will change in inverse proportion. In other words, when one goes up, the other goes down. It’s also quite useful in another formulaic representation, which allows us to calculate the resultant volume (or pressure,) assuming the initial volume & pressure and resultant pressure (or volume) is known:
P1and P2 are the initial, and resultant, pressures (respectively) and
V1and V2 are the initial, and resultant, volumes (respectively)
This is in fact, what happens when compressed air is generated, so this formula is instrumental in many aspects of air system design, such as determining compressor output, reservoir storage, pneumatic cylinder performance, etc.
Back to the reason it’s called “Boyle’s Law” – it’s not because he discovered this particular phenomenon. See, in April of 1661, two of Robert Boyle’s contemporaries, Richard Towneley and Henry Power, actually discovered the relationship between the pressure and volume of a gas when they took a barometer up & down a large hill with them. Richard Towneley discussed his finding with Robert Boyle, who was sufficiently intrigued to perform the formal experiments based on what he called “Mr Towneley’s hypothesis.” So, for completing the steps of Scientific Method on this phenomenon – going from hypothesis to law – students, scientists, and engineers remember Robert Boyle.
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As Application Engineers, we help many customers with finding solutions with effective, safe, and efficient EXAIR products. But, in some instances, we get a request for an air amplifier to increase line pressures. EXAIR does not manufacture this type of Air Amplifier. In doing some research on the internet, I was able to find two different types of air amplifiers. In this blog, I will describe the difference between the pressure-type and volume-type.
The EXAIR Super Air Amplifiers are defined as a volume-type of an amplifier. They use compressed air to generate a large volume of air flow. The amplification ratio is the comparison between the inlet air flow and the outlet air flow. With the EXAIR Super Air Amplifiers, we can reach an amplification ratio of 25 to 1. They use a Coanda profile with a patented shim to create a low pressure to draw in a large volume of the surrounding air. EXAIR manufactures a variety of different sizes, materials, and types. But they all do the same thing, amplify the volume of air. To give an example, model 120024 Super Air Amplifier has a 25:1 amplification ratio. It uses 29.2 SCFM (826 SLPM) of compressed air at 80 PSIG (5.5 bar). So, the outlet air flow is amplified from 29.2 SCFM to 730 SCFM (20,659 SLPM) of air. This large volume of air works great for cooling, exhausting, and transferring. But, with any type of amplification, you have to lose something. With the volume type Air Amplifiers, the outlet pressure is reduced dramatically.
The pressure-type air amplifiers are different from the Super Air Amplifiers as this device will amplify the outlet air pressure, not the volume. It is an air pump that has a direct dual piston that uses two different diameters. The larger diameter uses the drive inlet pressure while the smaller diameter is used for the boost pressure. The amplification ratio is determined by the difference in volume from the drive piston to the boost piston. They also come in a variety of ranges and sizes. As an example, an amplification ratio of 15:1 will increase an inlet pressure from 100 PSI (7 bar) to an outlet pressure of 1,500 PSI (103 bar). Since the pressure-type air amplifier is an air pump, the system has to cycle. To do this, they use pilot valves to either add the inlet compressed air to the drive piston or to relieve the air pressure from the drive piston. This cycling portion of the operation does reduce the efficiency of the air amplifier. The pressure-type air amplifiers are used to generate high pressure for a specific application or area and eliminate the purchase of a high-pressure air compressor. The applications include air clamps and presses, pressure testing, air brakes, and also blow molding. Like stated above about losing something with amplifications, the volume of air is reduced dramatically. Generally, a reservoir tank and over-sizing will be needed for a good system.
The Application Engineers at EXAIR enjoy talking to customers about compressed air applications. If you need more information about Air Amplifiers, you can contact us directly. We can explain the volume-type that we manufacture or refer you to a company that makes the pressure-type. Either way, we will be happy to hear from you.
When the topic of Air Amplifiers comes up, there are two avenues to consider – is it the air pressure or the air volume that you wish to amplify? There exists technologies to amplify either parameter, and we will examine them both.
There may be equipment or processes within a facility that operate best at air pressures higher than can be delivered, due to air compressor limitations or the supply system. An Air Pressure Amplifier can take the existing compressed air supply, and boost the pressure allowing for the higher needed air pressure without requiring a dedicated compressor capable of operating at the higher pressure.
An Air Pressure Amplifier is basically an air pump, driven by a portion of the compressed air supply. The pump cycles and compresses the remaining amount of compressed air to a higher outlet pressure. This higher output pressure can be used to operate the equipment or process that required the pressure levels that the base system could not supply. The drawback is that the pump system consumes a good amount of the compressed air volume, to power the pump which reduces the amount of air available for other equipment or processes. This drives up the compressed air consumption for the system, and requires the extra capacity to operate.
The other type of Air Amplifier is the kind that amplifies the air flow volume. EXAIR manufactures this type of amplifier.
The air flow amplification works by taking compressed air (1) and directing into an annular chamber (2). It is then throttled through a small ring nozzle (3) at high velocity. This primary stream of air adheres to the Coanda profile (4) and is directed through the outlet. A low pressure area is created at the center, inducing a high volume flow (5) of surrounding air to be drawn in and added to the main air stream. The combined flow of primary and surrounding air exits as a high volume, high velocity flow.
EXAIR manufactures (2) types of Air Amplifiers, the Super Air Amplifier and the Adjustable Air Amplifier. In addition, a special model for High Temperature applications is available. Sizes range from 3/4″ (19mm) to 8″ (203mm) to meet most air flow requirements. Air amplification ratios start at 12:1 for the 3/4″ model and increase to 25:1 for the 4″ and 8″ models.
Charts and tables are available to help determine the right Air Amplifier for the job.
If you have questions about the Air Amplifiers, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
What is Air? Air is an invisible gas that supports life on earth. Dry air is made from a mixture of 78% Nitrogen, 21% Oxygen, and 1% of remaining gases like carbon dioxide and other inert gases. Ambient air contains an average of 1% water vapor, and it has a density of 0.0749 Lbs./cubic foot (1.22 Kg/cubic meter) at standard conditions. Air that surrounds us does not have a smell, color, or taste, but it is considered a fluid as it follows the rules of fluid dynamics. But unlike liquids, gases like air are compressible. Once we discovered the potential of compressing the surrounding air, we were able to advance many technologies.
Guess when the earliest air compressor was used? Believe it or not, it was when we started to breathe air. Our diaphragms are like compressors. It pulls and pushes the air in and out of our lungs. We can generate up to 1.2 PSI (80 mbar) of air pressure. During the iron age, hotter fires were required for smelting. Around 1500 B.C., a new type of air compressor was created, called a bellows. You probably seen them hanging by the fireplaces. It is a hand-held device with a flexible bag that you squeeze together to compress the air. The high stream of air was able to get higher temperature fires to melt metals.
Then we started to move into the industrial era. Air compressors were used in mining industries to move air into deep caverns and shafts. Then as the manufacturing technologies advanced, the requirements for higher air pressures were needed. The stored energy created by compressing the air allowed us to develop better pneumatic systems for manufacturing, automation, and construction. I do not know what the future holds in compressed air systems, but I am excited to find out.
Since air is a gas, it will follow the basic rules of the ideal gas law;
PV = nRT (Equation 1)
P – Pressure
V – Volume
n – Amount of gas in moles
R – Universal Gas Constant
T – Temperature
If we express the equation in an isothermal process (same temperature), we can see how the volume and pressure are related. The equation for two different states of a gas can be written as follows:
P1 * V1 = P2 * V2 (Equation 2)
P1 – Pressure at initial state 1
V1 – Volume at initial state 1
P2 – Pressure at changed state 2
V2 – Volume at changed state 2
If we solve for P2, we have:
P2 = (P1 * V1)/V2 (Equation 3)
In looking at Equation 3, if the volume, V2, gets smaller, the pressure, P2, gets higher. This is the idea behind how air compressors work. They decrease the volume inside a chamber to increase the pressure of the air. Most industrial compressors will compress the air to about 125 PSI (8.5 bar). A PSI is a pound of force over a square inch. For metric pressure, a bar is a kg of force over a square centimeter. So, at 125 PSI, there will be 125 pounds of force over a 1” X 1” square. This amount of potential energy is very useful to do work for pneumatic equipment. To simplify the system, the air gets compressed, stored as energy, released as work and is ready to be used again in the cycle.
Compressed air is a clean utility that is used in many different applications. It is much safer than electrical or hydraulic systems. Since air is all around us, it is an abundant commodity for air compressors to use. But because of the compressibility factor of air, much energy is required to create enough pressure in a typical system. It takes roughly 1 horsepower (746 watts) of power to compress 4 cubic feet of air (113L) to 125 PSI (8.5 bar) every minute. With almost every manufacturing plant in the world utilizing compressed air in one form or another, the amount of energy used to compress air is extraordinary. So, utilizing compressed air as efficiently as possible is mandatory. Air is free, but making compressed air is expensive
If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Products, you can contact an Application Engineer at EXAIR.
Every day I speak with engineers who are having trouble using compressed air products. A common problem they have is not providing an adequate air supply to their unit. I go through a basic troubleshooting technique to ensure that their pressure and flow rate is adequate. I ask them to install tee on the inlet to the compressed air product in order to install a pressure gauge right at the inlet to the pipe. This allows us to know exactly what pressure we are supplying to the product. Customers are always surprised how the gauge on the compressor or the regulator may read 120 PSIG, but the gage on the inlet to the compressed air product is significantly less.
Last year, my colleague, Russell Bowman, made an excellent video showing how the inlet pressure at the knife will have a significant impact on the performance of the Super Air Knife. In the video, he changes the length and ID of the compressed air supply to illustrate the difference a proper supply line will have on the performance of a compressed air products.
Not providing adequate air supply is commonly caused by these three mistakes, when plumbing compressed air systems.
1. Incorrectly Sized Piping – This can be the single biggest problem. A lack of planning before installing a compressed air product. Not all compressed air systems are created equal. Though a 1/4″ shop air hose may work for a number our products, some of our products require a larger air line because they require more volume of air to be effective. We often speak with customers an illustrate this problem by stating small air lines are like trying to feed a fire hose with a garden hose – there simply is not enough volume to create the pressure necessary to reach the fire, or solve the application in our scenarios. We publish the flow rates for all of our products and make inlet pipe size recommendation in the installation and maintenance guide furnish with the products so you may avoid this common problem. We also have air data tables in our Knowledge Base or you may consult an application engineer who will be happy to make the proper recommendation.
2. Quick Disconnects – These handy connectors are great when operating a brad nailer, or a small blow gun, but the small through diameter can severely limit the flow rate into a long air knife, large diameter air operated conveyor, or big vortex tubes. Due to this fact it is strongly advised to use threaded fittings or over-sized quick disconnects.
3. Adding extra hose or pipe – Extra hose is never a bad thing, right? No, an extra 30 feet of air hose can significantly drop the pressure of a compressed air system. 20 feet of ½ Pipe can flow 70 CFM with a 5 PSI pressure drop. 50 feet of ½” pipe will only flow 42 SCFM with the same 5 PSIG pressure drop. Keep your hose or pipe lengths to a minimum to improve the volume of air you can deliver to a compressed air product.
The five C’s of EXAIR products are Cooling, Cleaning, Conserving, Conveying, and Coating. All EXAIR products are suitable for applications in these areas, with varying degree of possibility. When it comes to cooling, one of the most suitable EXAIR products is the Super Air Amplifier.
An Air Amplifier can increase the volume of ambient air directed over an specific area, effectively decreasing the cooling time needed in an application. Air Amplifiers cool effectively due to the fundamental principles of convective heat transfer. In convective heat transfer, cooling capacity can be increased by increasing the temperature differential between the cooling medium and the object to be cooled, or by increasing the flow of the cooling medium.
An Air Amplifier is the best cooling choice when the material to be cooled is at an extremely high temperature. For example, in the application above, 903°C (1650°F) cylinders need to be cooled to ambient temperature as quickly as possible. Vortex Tubes are another product our customers consider for cooling applications. Vortex Tubes are the best choice when the area to be cooled is small and the temperature differential is not as large. A Vortex Tube based solution will provide very cold air, but at a lower air flow over a small area and they were not the best choice for the application in the image above.
In the same application, a Super Air Amplifier can provide large volumes of ambient air over a large area, effectively cooling the cylinders much more efficiently. The cooling can be achieved in less time, and with maximum efficiency of compressed air implementation. Air Amplifiers also offer great benefits over electric fans in this rough environment: they can withstand higher temperatures and there are no moving parts to wear or break.
If you have an application in need of efficient cooling, contact an EXAIR Application Engineer to find out if an Air Amplifier will work for you.