Super Air Knife – Free Air Via a 40:1 Amplification Ratio

Intelligent Use of Compressed Air – Most industrial facilities have at least one air compressor.  The compressor is used to power anything from pneumatic tools, air powered equipment, compressed air cylinders, blowoffs and many more types of operations.  Improper use of compressed air can lead to unnecessary energy costs, high noise levels and dangerous exposure of personnel to high pressure air.

The EXAIR Super Air Knife uses only 1/3 of the compressed air of typical blowoffs.

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Long Super Air Knife with Plumbing Kit Installed and using the model 9060 Universal Air Knife Mounting Kit to Blowoff Laser Cutting Debris

By taking advantage of the Super Air Knife’s highly efficient design and the action of air entertainment, the Super Air Knife draws in large amounts of surrounding free outside air into the air stream. The result is a strong powerful air flow made up of a small amount of compressed air and a large amount of ambient air.

Capture

  • Compressed air flows through an inlet (1) into the plenum chamber of the Super Air Knife. The flow is directed to a precise slotted orifice. As the primary airflow exits the thin slotted nozzle (2), it follows a flat surface that directs the airflow in a perfectly straight line.  This creates a uniform sheet of air across the entire length of the Super Air Knife. Velocity loss is minimized and force is maximized as room air (3) is entrained into the primary air stream at a ratio of 40:1.  The result is a well defined sheet of laminar airflow with hard-hitting force and minimal wind shear is delivered.

By using a Super Air Knife – and the advantage of the high amplification via air entertainment – for part blowoff, cooling, or drying you can reduce energy costs, reduce noise levels, and eliminate harmful dead end pressures. Other air knives typically entrain surrounding air at a ratio of 30:1 or less.

EXAIR offers the Super Air Knife with materials of construction of aluminum, Types 303 and 316 Stainless Steel, and PVDF to cover a wide variety of application temperatures and environments. Other materials may be possible, pending review by our Product Design Engineers. The Super Air Knives are offered as the knife only, as part of a full kit, which also includes a shim set, auto drain filter separator, and pressure regulator.  The Super Air Knife can be fitted with Plumbing Kits and/or Electronic Flow Control making installation easier and help to save on air usage.

If you have questions about Super Air Knives, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Air: What is it?

Air Balloons

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.

Bellows

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.

Air Compressor

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.

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

 

Picture: Hot Air Rises by Paul VanDerWerf. Creative Commons Attribution 2.0 Generic.

Picture: Bellows by Joanna Bourne. Creative Commons Attribution 2.0 Generic.

Picture: Air Compressor by Chris Bartle. Creative Commons Attribution 2.0 Generic.