Because of the large amount of energy required to run an air compressor, the pneumatic system is considered the fourth utility in a manufacturing plant. And saving this commodity and using it as efficiently as you can, should be a priority. EXAIR has many products that can save this energy safely and effectively. And the story behind the efficiency of EXAIR products is Bernoulli’s equation.
Bernoulli’s principle explains how a high velocity fluid can generate a low pressure. (You can read more about Bernoulli’s principle HERE.) Let’s start by looking at Equation 1.
Equation 1:
P + p * V2/2 = C
P – pressure
p – density of the fluid
V – velocity
C – a constant
As you can see from Equation 1, when the velocity goes up, the pressure must go down. When we have a lower pressure, then the surrounding fluid will have to fill that void. Since air is a fluid, this is how we can entrain the free ambient air while only using a small amount of compressed air. Bernoulli’s Principle can be applied in two ways; as a Coanda and as a Venturi. EXAIR uses both methods in our products for creating low-pressure effects.
The first way is from a Coanda profile. Coanda, named after Henri Coanda, noticed that a fluid would “hug” a curved surface. (You can read more about Henri Coanda HERE.) The high velocity air going around the curved surface will generate a low pressure above it. We use this with our Full Flow and Standard Air Knives, our Air Wipes, and our Air Amplifiers. With a Coanda profile, the low pressure will entrain the surrounding air to add mass to the air stream. We can get an amplification ratio up to 30:1, which means that for every 1 part of compressed, 30 parts of ambient air are entrained. We are able to create an efficient air moving (blow-off) device by using the Coanda profile.
Generating even lower pressures can be accomplished with a Venturi. This phenomenon is named after Giovanni Venturi, who discovered that by increasing the velocity through an orifice, the surrounding fluid will move with it, generating a lower pressure. (You can read more about Giovanni Venturi HERE.) Remember the higher the velocity, the lower the pressure. We use the Venturi effect on our Super Air Knives, E-Vacs, Line Vacs, and Super Air Nozzles. When compared to our Full Flow and Standard Air Knives, the Super Air Knives can generate an amplification ratio of 40:1. We were able to engineer the product to increase the air entrainment efficiency even further.
EXAIR has been manufacturing Intelligent Compressed Air® products since 1983. We provide solutions that are efficient, effective, and safe for air moving and blow-off systems. Consider the following analogy; homemade air movers and blow-off devices are the equivalent to incandescent light bulbs. EXAIR products are the equivalent to LED light bulbs. More efficient design leads to lower operating cost, higher efficiency and a higher level of effectiveness. Entrainment of free ambient air can save you a lot of money and increase your mass flow with your compressed air use to generate higher forces on your targets. If you would like to discuss solutions to use less compressed air, an Application Engineer is available to help.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb