Calculating CFM of Air Needed for Cooling

It’s easy to know that EXAIR’s vortex tubes can be used to cool down parts and other items, but did you know that our air knifes can be used to cool down these same things? It’s the same process that we do every day to cool down hot food by blowing on it. Every molecule and atom can carry a set amount of energy which is denoted by physical property called Specific Heat (Cp); this value is the ration of energy usually in Joules divided by the mass multiplied by the temperature (J/g°C). Knowing this value for one can calculate the amount of air required to cool down the object.

Starting out you should note a few standard values for this rough calculation; these values are the specific heat of Air and the specific heat of the material. Using these values and the basic heat equation we can figure out what the amount of energy is required to cool. The specific heat for dry air at sea level is going to be 1.05 J/g*C which is a good starting point for a rough calculation; as for the specific heat of the material will vary depending on the material used and the composition of the material.

Heat Flow Equation
Using the standard heat equation above add in your variables for the item that needs to be cooled down. In the example I will be using a steel bar that is 25 kg in mass rate and cooling it down from 149 °C to 107 °C. We know that the specific heat of steel is 0.466 J/g°C therefore we have everything needed to calculate out the heat load using air temperature of 22 °C.
Calculating Joules/min
Using the heat rate, we can convert the value into watts of energy by multiplying the value by 0.0167 watts/(J/min) which gives us 16,537.18 watts. Furthermore, we can then convert our watts into Btu/hr which is a standard value used for cooling applications. Watts are converted into Btu/hr by multiplying by 3.41 Btu/hr/watt, giving us 56,391.77 Btu/hr.
Converting Joules to Btu/hr
Once you have Btu/hr you can plug the information into a re-arranged Cooling power formula to get the amount of CFM of air required for cooling.
Calculating CFM
As you can see in order to cool down this steel bar you only need to 343 CFM of air at 72°F. This can be done very easily and efficiently by using one of EXAIR’s Air Amplifiers or Air Knife. Sometimes you don’t need to use a vortex tube to cool down an object; sometimes simply blowing on it is good enough and its pretty simple to calculate out which product would fit your application the best.

If you have any questions about compressed air systems or want more information on any EXAIR’s of our products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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Usefulness of a Coanda Profile

How did a past inventor help generate efficient compressed air products for EXAIR?  In the early 20th century, Henri Coanda who was a Romanian aeronautical engineer that built an experimental Coanda-1910 airplane.  There are some debates if the airplane actually flew, but he invented a curved surface for a wing to generate a Coanda effect. The Coanda effect is the “tendency of a fluid jet to stay attached to a convex surface”1.   Thus, a moving stream of fluid will follow the curvature of the surface rather than continuing to travel in a straight line.  The Wright Brothers who flew the first airplane in the state where EXAIR is located, Ohio, used the Coanda effect to create lift.  With a curved profile, the air will adhere to the surface, causing a low pressure which makes the airplane fly.

Standard Air Knife

Super Air Amplifier with shims

EXAIR uses this Coanda profile to make some of our Intelligent Compressed Air Products™.   Like the airplane wing, our curved surface will also create a low pressure.  How does this help?  Well, high pressure will always travel to low pressure.  Instead of lift, we use the low air pressure to entrain ambient air.  This ratio is what we call the amplification ratio.  The higher the amplification ratio, the higher the efficiency for a blowing device. Two main compressed air products that EXAIR manufactures use this type of profile; Air Knives and Air Amplifiers.  I will cover both below.

Compressed air flows through the inlet (1) to the Standard Air Knife, into the internal plenum. It then discharges through a thin gap (2), adhering to the Coanda profile (3) which directs it down the face of the Air Knife. The precision engineered & finished surfaces optimize entrainment of air (4) from the surrounding environment.

The Air Knives that use the Coanda profile blows air along the length of the knife at a 90o angle from the exit.  We offer two types; the Standard Air Knife and the Full Flow Air Knife.  The Standard Air Knives are made in Aluminum or Stainless Steel with blowing widths up to 48” (1219mm).  The inlet ports are at each end; so, the overall length is 1” (25mm) longer.  The Full Flow Air Knives have the port or ports on the back.  The air blows out the entire length of the air knife.  The maximum length is 36” (914mm).

Both types of air knives use the Coanda profile to generate a low pressure as the air exits the gap and “hugs” the curve (reference photo above).  This low pressure draws ambient air into the air stream at a 30:1 amplification ratio for both the Standard Air Knife and Full Flow Air Knife.  So, for every one part of compressed air, we entrain 30 parts of ambient air.  Besides efficiency, it also adds mass to the air stream for a hard-hitting force.  With this engineered profile, the air stream is laminar which gives a consistent force across the entire length and reduces noise levels.  Not only will they save you money,  but they are also OSHA safe.

Air Amplifiers use the Coanda Effect to generate high flow with low consumption.

The Air Amplifiers use the Coanda profile in a circular form to pull in dramatic amounts of free surrounding air.  The Coanda effect is able to generate a low pressure to blow air for cooling, cleaning or removing smoke and debris efficiently and quietly.  The Air Knives above blow a flat stream of air while the Air Amplifiers will blow a conical air stream.  They can reach amplification ratios up to 25:1. The Super Air Amplifiers use a patented shim to increase efficiency.

Unlike fans, they blow a laminar air stream for quick cooling.  They do not have any moving parts or motors to wear, so they are very quiet.  EXAIR manufactures five different sizes from ¾” (19mm) to 8” (203mm).  The Adjustable Air Amplifiers have a plug that can be adjusted to control the blowing force from a breeze to a blast.  For cleaning surfaces, this is a nice feature to “dial” in to exactly what you need.  We also manufacture five different sizes in aluminum and stainless steel ranging from ¾” (19mm) to 4” (102mm).  Both Air Amplifiers can be attached to ducts to remove debris, heat or smoke from the area.

Utilizing the Coanda effect allows for massive compressed air savings. Whether it is a flat or round air stream, EXAIR can do this with high amplification ratios.  If you would like to discuss further how our Air Knives or Air Amplifiers can help you in your applications, please contact us. An Application Engineer will be happy to help you.  History has shown us a way to increase efficiency when using compressed air.  And you can take advantage of it with the Coanda profile.  Thank you Mr. Henri Coanda.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

1note – Wikipedia – Coanda effect

Super Air Amplifiers and Amplification Ratio

Super Air Amplifier Family

In the pneumatic industry, there are two types of Air Amplifiers.  One type will amplify the inlet air pressure to a higher compression.  The other type uses the inlet air pressure to amplify the air volume.  EXAIR manufactures the volume type called the Super Air Amplifiers™.

This change in air volume is called the amplification ratio.  So, what does this mean?  The definition of a ratio is the relation between two amounts showing the number of times one value is contained within the other.  For the Super Air Amplifier, it is the value that shows the amount of ambient air that is contained within the compressed air.  The higher the ratio, the more efficient the blowing device is.  With the EXAIR Super Air Amplifiers, we can reach amplification ratios up to 25 to 1.  This means that 25 parts of ambient “free” air is introduced for every 1 part of compressed air.

Air Amplifiers Are Great For blowing!

Why an EXAIR Super Air Amplifier?  Like a fan, they are designed to move air.  But fans use motors and blades to push the air toward the target.  The fan blades “slap” the air which creates turbulent air flows and loud noises. The Super Air Amplifiers do not use any blades or motors to move the air.  They just use a Coanda profile and a patented shim to create a low pressure to draw in the ambient air.  In physics, it is much easier to pull than it is to push.  The process of pulling air through the Super Air Amplifiers make them a more efficient, uniform, and quiet way to blow air.

Most people think that compressed air is free, but it is most certainly not.  Because of the amount of electricity required, compressed air is considered to be the fourth utility in manufacturing plants.  To save on utility costs, it is important to use compressed air as efficiently as possible.  In reference, the higher the amplification ratio, the more efficient the compressed air product.  Manufacturing plants that use open fittings, copper tubes, and drilled pipes for blowing are not properly using their compressed air system.  These types of products generally only have between a 2:1 to 5:1 amplification ratio.  The Super Air Amplifiers can reach a 25:1 ratio.

EXAIR manufactures and stocks five different sizes ranging from ¾” (19mm) up to 8” (203mm) in diameter.  Some of the benefits that the Super Air Amplifiers have is the inlet and outlet can be ducted for remote positioning.  They are very compact and can fit into tight places.  They do not have any moving parts to wear or need electricity to run.  They only need clean compressed air to operate; so, they are maintenance-free.

Another unique feature of the EXAIR Super Air Amplifier is the patented shim which optimizes the low-pressure to draw in more ambient air.   With extracting welding smoke, increasing cooling capacities, and moving material from point A to point B; the more air that can be moved, the better the performance.  And with the patented shim inside the EXAIR Super Air Amplifiers, it provides that.  As an added bonus, they are OSHA safe and meet the standards for noise level and dead-end pressure.

Super Air Amplifier Patented Shims

To explain things in every day terms; the amplification ratio can be represented by gas mileage.  Like your car, you want to get the most distance from a gallon of gasoline.  Similarly, with your compressed air system, you want to get the most for your pneumatic equipment.  An EXAIR Super Air Amplifier has a 25:1 amplification ratio.; so, in other words, you can get 25 mpg.  If you use drilled pipes, open fittings, copper tubes, etc. for blowing, then you are only getting 2 to 5 mpg.  If you want to get the most “distance” from your compressed air system, you should check the “gas mileage” of your blow-off components.  If you need assistance, an Application Engineer at EXAIR can help you to “tune up” your compressed air system.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Two Types of Air Amplifier: Pressure vs Volume Amplifiers

In the compressed air world, when we talk about an “air amplifier” it can mean one of two things: either a pressure air amplifier, or a volume air amplifier. How do we differentiate the two and what types of applications does each serve?

A pressure air amplifier works as an air pump to increase the pressure of the supplied air, generating pressures ranging from 30 psi up to as much as 1500 psi in some specialized types of pressure amplifiers. Pressure air amplifiers operate only off of the supplied compressed air and do not require a source of electricity to drive the piston amplifying the pressure. They are available in both single-acting and double-acting varieties with the double-acting being the most efficient.

Pressure-type air amplifiers are used in applications where a specific product or process must have a higher pressure than the compressor system can deliver. This includes applications such as: air clamps, presses, pressure testing, air brakes, and also blow molding. The drawback to these products is that the increase in pressure does result in a reduction in volume of air. A point of use receiver tank and over-sizing of the overall system is generally a good practice to ensure sufficient operation.

salapp

On the other side of the amplifier spectrum lies EXAIR with our volume amplifying amplifiers. EXAIR manufactures two different styles of volume air amplifier: The Super Air Amplifier and Adjustable Air Amplifier. These products utilize Bernoulli’s Principle and the coanda effect to draw in large amounts of ambient air that mixes with the supplied compressed to project a hard hitting force of laminar airflow, much greater than what is supplied.

EXAIR’s Adjustable Air Amplifiers are available in both Stainless Steel and Aluminum from sizes ranging from ¾”-4” on the air outlet. The outlet can be ducted or it can be used as-is. The air gap of the Adjustable Air Amplifier is infinitely adjustable, allowing you to regulate both the air consumption and outlet flow from a “breeze” to a “blast”. In addition to the standard Adjustable Air Amplifiers, we also have a High Temperature Air Amplifier available that is capable of withstanding temperatures as high as 700°F.

aalapp4

aal-vacuum

 

 

 

 

 

 

 

 

 

EXAIR’s Super Air Amplifiers utilize a patented shim design to maintain critical positioning of component parts. This allows a precise amount of compressed air to be released at exact intervals toward the center of the Super Air Amplifier. This creates a constant, high velocity outlet flow across the entire cross-sectional area. Free, ambient air is entrained through the unit, resulting in high amplification ratios. The balanced outlet airflow minimizes wind shear to produce sound levels far lower than other similar air movers.

Volume air amplifiers can be used in a variety of blowoff, conveying, drying, cooling, and venting applications. With a range of different sized Super Air Amplifiers and Adjustable Air Amplifiers, EXAIR has a solution for you if you need to move A LOT of air for a variety of reasons. Reach out to an Application Engineer today if you have an application that you believe could be served with a low-cost, simple solution!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter:@EXAIR_TD

Custom Air Amplifiers: Customization to Fit Your Needs

EXAIR’s line of Air amplifiers can be found in thousands of applications across the world from everything as simple as blowing parts off to exhausting fumes. The Air Amplifier comes in two different styles either the Super Air Amplifier or the Adjustable Air Amplifier. Super Air Amplifiers come in a stock Aluminum Body with a diameter that ranges from ¾” to 8”. This differs from the Adjustable Air Amplifier which comes in either type 303 Stainless Steel or Aluminum and are Sized from ¾” to 4”.

Super Air Amplifiers are supplied with a .003″ (0.08mm) slotted air gap which is ideal for most applications. Flow and force can be increased by replacing the shim with a thicker .006″ (0.15mm) or .009″ (0.23mm) shim. Model 120028 is supplied with a .009″ (0.23mm) air gap. A .015″ (0.39mm) shim is available for Model 120028.

Even though there is a wide variety of sizes and materials for the Stock Air Amplifiers they don’t always match a customer’s specific need or application. Over the years EXAIR has produced a slew of different custom Air Amplifiers for a customer’s specific need and the following are just a few of what we have done.

  • Depending on the environment certain specific materials may be required like the food industry which requires specific Stainless Steel for various applications. One customer had a special PTFE plug made for the Adjustable Air Amplifier to help pull a sticky material through the process. The PTFE helped prevent the material from depositing on the inside diameter of the Amplifier.
  • For applications where mounting may be an issue, special attachments have been made to assist. For instances where an Amplifier may need to be mounted to a pipe, we manufactured a custom Stainless-Steel Adjustable Air Amplifier with class a 150 raised face flange.
  • Applications that are in a hot environment may require a special high temperature version which has be developed to operate in areas up to 700°F. The High Temperature Air Amplifier was so widely sought after that we turned it into a stock item.

No matter what your application is EXAIR is capable to work with you to create custom solutions for your application. Whether you need a different material, size or shim thickness, EXAIR is able to meet your requirements. These Air Amplifiers represent only one of our many product lines that can be custom made to your specifications. 

For more information on EXAIR’s Air Amplifiers or help with customizing any of EXAIR‘s Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Cody Biehle
Application Engineer
EXAIR Corporation
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EXAIR Super Air Amplifiers – Circulate, Blow, Dry, Cool, Vent

Super Air Amplifier

EXAIR manufactures a volume-type amplifier called the Super Air Amplifier. Not to be confused with its cousin, the pressure-type amplifier which increases air pressure, these devices increase the volume of air. This is a great benefit for circulating, cooling, blowing, drying and transferring materials like smoke fumes or lightweight items. With a range of applications, the EXAIR Super Air Amplifiers can be a simple solution for your company.

Super Air Amplifier – flow region

Why an EXAIR Super Air Amplifier? Like a fan, they are designed to move air. But fans use motors and blades to push the air toward the target. The fan blades “slap” the air which creates turbulent air flows and loud noises. The Super Air Amplifiers does not have any blades or motors to move the air. It just uses a Coanda profile and a patented shim to create a low pressure to draw in the air. With physics, it is much easier to pull than it is to push. The method in pulling air through the Super Air Amplifier makes a more efficient, uniform, and quiet operation to blow air.

How It Works

To expand, Coanda was named after a Romanian aerodynamic pioneer, Henri Coanda where he found a fluid flow phenomenon. He stated that “a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops” (1). Since air is a fluid, it will react in the same way. The EXAIR Super Air Amplifiers create a high velocity air stream along an engineered profile. So, as the air “hugs” the profile, a low pressure is created which will draw in ambient air. The ratio between the volume of air produced compared to the volume of compressed air needed is called the amplification ratio. The higher the ratio, the more efficient the blowing device is. With the EXAIR Super Air Amplifiers, we can reach amplification ratios up to 25 to 1.

Super Air Amplifier Family

EXAIR manufactures and stocks five different sizes ranging from ¾” (19mm) up to 8” (203mm) in diameter. One of the unique features with the Super Air Amplifiers is that the inlet and outlet can be ducted for remote positioning. They are very compact and can fit into tight places. They do not have any moving parts to wear, or need electricity to run; or require any maintenance. They only need clean compressed air to work. One of the unique features of the EXAIR Super Air Amplifier is the patented shim which optimizes the low-pressure to draw in more ambient air. For extracting welding smoke, increasing cooling capacities, and moving material from point A to point B; the more air that can be moved, the better the performance. And the patented shim inside the EXAIR Super Air Amplifiers provides that. As an added bonus, they are OSHA compliant for safety and meet the standards for noise level and dead-end pressure.

Patented Air Amplifier Shims

EXAIR offers the Super Air Amplifiers in kits for a more complete system. The kit will include a filter separator, a pressure regulator and a Shim Set. The filter can remove debris and water from the compressed air line to keep the Super Air Amplifier and your product clean. The regulator is used to make “fine” adjustments to the blowing volume while the Shim Set is used as a “coarse” adjustment. The Shim Set includes different thicknesses of shims to set the gap. The Super Air Amplifiers come standard with a 0.003” (0.08mm) thick shim for the sizes ¾” (19mm) up to 4” (102mm), and a 0.009” (0.23mm) thick shim for the 8” (203mm) size. The Shim Set will include (1) 0.006” (0.15mm) and (1) 0.009” (0.23mm) shim for the models 120220 through 120224 or (1) 0.015” (0.39mm) shim for the model 120228. EXAIR sells these kits as one model number for simple ordering and for proper sizing of the accessories to not hinder the performance of the Super Air Amplifiers.

120224DX

To optimize the system even more, EXAIR also offers a Deluxe Kit for the Super Air Amplifier models. This will include the accessories in the kit above, plus an Electronic Flow Control, or EFC. This exclusive instrument uses a photoelectric eye to start a timing sequence to control a solenoid valve. So, when a part is not in front of the Super Air Amplifier, the compressed air is turned off. This will save you even more money and maximize your efficiency to only blow air when needed. They can be ordered with the kits by placing a “DX” at the end of the model number, such as 120224DX.

With the today’s cost to make compressed air, it is important to use it as efficiently as possible. The EXAIR Super Air Amplifiers have the ability to give effective blowing to remove debris, dry parts, transport material, or cool objects without using a large amount of compressed air. EXAIR has the Super Air Amplifiers in stock and as always, EXAIR offers a 30-day unconditional guarantee for our customers in the U.S. and Canada to try them out. If you have any questions about the Super Air Amplifiers or if you would like to discuss your application, an Application Engineer at EXAIR will be happy to help you.

 

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

 

(1) Note: Coanda effect by Wikipedia.org https://en.wikipedia.org/wiki/Coand%C4%83_effect

2″ Super Air Amplifier Exhausts Welding Fumes

EXAIR’s Super Air Amplifiers utilize a patented shim design to maintain critical positioning of component parts. This allows a precise amount of compressed air to be released at exact intervals toward the center of the Super Air Amplifier. This creates a constant, high velocity outlet flow across the entire cross-sectional area. Free, ambient air is entrained through the unit, resulting in high amplification ratios. The balanced outlet airflow minimizes wind shear to produce sound levels far lower than other similar air movers.

AirAmplifiers

While most applications utilize the outlet flow of the Super Air Amplifier to blow off or cool a part or material, the ability of the Super Air Amplifier to entrain large amounts of ambient air can also be utilized to convey light materials or to draw in dust, smoke, or fumes from the surrounding environment.

Recently I worked with a customer on an application to install the Model 120022 Super Air Amplifier in welding booths. They did have a current fume extraction system in place, but due to the distance between the vent hoods and the operation some of the fumes were still not being captured. The suggestion was to install a 2” Model 120022 at each booth near the origin of the welding fumes. As the exhaust side of the Super Air Amplifiers come in sizes of ¾”, 1-1/4”, 2”, 4”, and 8” the exhaust flow can be ducted with standard size hose. The placed a 2” ID hose onto the exhaust of the Super Air Amplifier which allowed the fumes to be captured into the intake of the amplifier and be carried towards the vent hood.

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This eliminated a safety issue for the operators and was much less expensive than redesigning the entire welding booths and current extraction system. With no moving parts to wear out, the Super Air Amplifier requires absolutely zero maintenance when supplied with clean, dry compressed air. After installing onto each of their welding booths, operators were pleased with the performance and we were able to eliminate the safety hazard for this facility.

With a range of different sized Super Air Amplifiers as well as a line of Adjustable Air Amplifiers, EXAIR has a solution for you if you need to move A LOT of air for a variety of reasons. Reach out to an Application Engineer today if you have an application that you believe could be served with a low-cost, simple solution!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD