Tag: Adjustable Air Amplifier

Buy 1, Get 40 Free

Published on by Al WooffittLeave a comment

Buy one, get one free is a phrase many of us are familiar with. Most of the time it is a good thing; we all like free stuff. What would you say to buy one, get 30 free? Or even 40 free? That’s not far off how our Air Knives perform. They entrain large volumes of ambient air, so for every 1 SCFM of compressed air you are paying for, you are getting 30–40 SCFM of additional free ambient entrained air.

So how are our Air Knives able to do this? We explain this phenomenon in more detail in this blog here, but in summary, a Super Air Knife takes advantage of the Venturi Effect. Named after Giovanni Venturi, who found out that when you increase the speed of a fluid through an orifice, the surrounding fluid will move along with it. This creates a region of low pressure, and the faster the speed, the lower the pressure. With low pressure, the air around rushes in to fill that gap and join the airstream. The quantity of ambient air that gets ‘pulled’ into the airstream is entrained air, or free air.

The engineered surface of the Super Air Knife is designed to minimize as much loss in air speed as possible, which maximizes the amount of free air that is being entrained. The ratio between free air and compressed air used is called the amplification ratio. Super Air Knives have an amplification ratio of 40:1, with our Standard Air Knives having an amplification ratio of 30:1. For comparison, a pipe with holes drilled will have an amplification ratio of between 2:1 and 5:1. As you can see, with a Super Air Knife you are getting a much better deal on your compressed air usage.

This additional free air adds more mass, which allows the Super Air Knife to do more work. You will get a harder hitting force than a comparable product while using less compressed air. This makes Super Air Knives especially good for cooling and drying applications, where moving large volumes of air is ideal.

EXAIR Intelligent Compressed Air Products such as (left to right) the Air Wipe, Super Air Knife, Super Air Nozzle, and Air Amplifier are engineered to entrain enormous amounts of air from the surrounding environment.

It’s not just our Air Knives that take advantage of the Venturi effect to produce large amplification ratios. Many of our products are designed with efficiency in mind, including our Air Amplifiers, Air Wipes, and Air Nozzles and Jets, to name a few. If you would like to discuss how an EXAIR engineered compressed air product can amplify your process, then give us a call!

Al Wooffitt
Application Engineer

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Vortex Tubes For Spot Cooling Processes

Published on by Al WooffittLeave a comment

EXAIR’s Vortex Tubes are a great product for many cooling applications. When supplied with a clean and moisture-free source of compressed air, they will generate two streams of airflow, one hot and one cold. They are a low-cost and reliable solution, capable of producing temperatures ranging from -50°F to +260°F. We have flow rates from 2 SCFM to 150 SCFM, producing refrigeration over 10,000btu/hr.

We also have several other product lines that are great for cooling, like our Air Knives or Air Amplifiers. So, why would you choose a Vortex Tube? Our Air Knives and Amplifiers cool primarily by moving large volumes of ambient air. If you have a 400°F part that needs cooling to under 100°F, then hitting it with large amounts of 70°F ambient air is going to rapidly bring the temperature down. This does mean that there is a limit to how low of a temperature you can achieve with these products; our Air Knives and Amplifiers won’t be able to cool below ambient temperatures. Our Vortex Tubes, on the other hand, with temperatures as low as -50°F, can provide much more powerful cooling and targeted cooling.

Now you have determined that a Vortex Tube is right for you, you’ll need to decide between our two different series: 32XX and 34XX. The difference between the two model types comes down to the Cold Fraction, which is determined by where the Control Valve is positioned. When you open the Control Valve (by turning it counterclockwise, as shown by the blue arrow in the photo to the right), it decreases the Cold Fraction, which leads to a reduced flow and a significant drop in temperature in the cold air discharge. Conversely, closing the Control Valve (by turning it clockwise, indicated by the red arrow) boosts the cold air flow, but causes a smaller temperature drop. This ability to adjust is crucial for the Vortex Tube’s flexibility.

 You can set the Cold Fraction as low as 20%, which means that a small portion (20% to be precise) of the supply air is sent to the cold end, resulting in a significant temperature drop. On the flip side, you can crank it up to 80%, meaning that most of the supply air heads to the cold end, but the temperature drop won’t be as drastic. Our 34XX Series Vortex Tubes are designed for cold fractions between 20–50 %, while the 32XX Series caters to 50–80 % Cold Fractions.

So how do you select the right model for you? To determine this, you need to know what temperature and flow will best serve your application. For most situations, the ~20°F produced by an 80% cold fraction is sufficiently cold. At this cold fraction, you will get the most flow (80% of the inlet supplied). Applications like welding or brazing benefit from higher flows. When your starting temperature is hundreds of degrees Fahrenheit, there is little difference in blowing -20°F air vs +20°F. What you need is more volume to strip away the heat as quickly as possible. In this instance, a 32XX series is the way to go.

If you need lower flow, or to achieve freezing temperatures, then the 34XX series would be the best choice. A chocolate maker took advantage of the lower flow rates offered by this type of Vortex Tube as they didn’t want the airflow to disturb the surface of the chocolate as it cooled, affecting the finish. The greater temperature drop allowed for rapid cooling without reducing quality.

Vortex Tubes can produce higher levels of noise than our Knives and Amplifiers, so we would always recommend using hot and cold mufflers with them. This will ensure they stay within OSHA sound standards. And just like with all EXAIR products, it’s a good idea to use a pressure regulator with a gauge right where you’re using it. This is especially crucial for Vortex Tubes if you want to get an accurate temperature.

Whatever your cooling application, our Vortex Tubes will likely be able to help. If you would like to discuss it, please give us a call!

Al Wooffitt
Application Engineer

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Super Air Amplifier vs Fan

Published on by Al WooffittLeave a comment

One of the more common applications we work with is cooling. In most instances, the goal is to cool the part as quickly as possible. In order to cool faster, you would think that blowing the coldest air possible would be the best option. Our Vortex Tubes can produce air as cold as -50°F! However, in many instances, more effective cooling will be achieved through larger volumes of air. As long as the ambient air temperature is lower than the target temperature, larger volumes of ambient air will outperform a small volume.

Our Super Air Amplifier is a great option for producing large volumes of laminar (non-turbulent) airflow for minimal compressed air consumption. Using a Coanda profile along with a patented shim, compressed air exits the Amplifier in a manner that generates a low pressure zone, which helps pull in the surrounding ambient air. This creates an amplification ratio of up to 25 times! Due to the laminar output flow having the same speed and direction, it is very effective at removing heat from a target. It also helps keep noise levels down.

The most common, non-compressed air alternative to our Amplifiers is an electric fan. Fans utilize motors and blades to direct air towards their target. When air comes in from behind the fan, the blades push the air forward to the target. This action generates turbulent air flow, as well as a lot of noise. Due to the use of motors, there are parts that can wear out over time, leading to additional maintenance costs over the lifetime of the fan.

Ultimately, when it comes to cooling, what we care about most is how quickly a given solution will get the job done. Is a Super Air Amplifier going to cool faster than a fan? In the video below we put both options to the test. As you will see, the Super Air Amplifier is significantly faster:

If you have a cooling application that you would like to discuss, give us a call!

Al Wooffitt
Application Engineer

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Boosting Ventilation With Air Amplifiers

Published on by Russ BowmanLeave a comment

Entering a confined space comes with a number of risks:

  • Physical hazards: mechanical equipment, falling objects, structural collapse, etc. Historically, these account for about 20% of fatalities associated with confined space entry.
  • Engulfment hazards: that’s a less horrific way to say “buried alive.” These are similar to some physical hazards, except the danger is from asphyxiation instead of being crushed. A prime example of this would be a farmworker falling into a grain silo in such a way that their head is submerged in the volume of grain. About 11% of confined space entry fatalities involve engulfment accidents. EXAIR Line Vacs are actually used in emergency responses to these.
  • Atmospheric hazards: Without adequate ventilation, carbon dioxide can build up, displacing the oxygen that workers need to breathe. Toxic and flammable gases are in this category as well, and whether workers are asphyxiated or poisoned, failure to provide a safe atmosphere accounts for almost 60% of confined space entry deaths.

Before workers enter a confined space, permits are oftentimes required. Atmospheric monitoring and ventilation are key aspects of such permits: Monitoring to ensure an adequate level of oxygen and the reduction of toxic & flammable gases to safe exposure limits, and ventilation to make sure that happens. It’s generally recommended to have ventilation/exhaust equipment capable of providing 20 air changes per hour.

EXAIR Air Amplifiers are an easy & reliable choice for providing the required ventilation. With no moving parts to break or electrical components to fail, all they need is a supply of compressed air. So, how do we choose the right one? Since we know we need 20 air changes an hour, the first step is to determine the volume of the space. Let’s say we need to enter a 10ft x 6ft x 6ft tank:

  • 10ft x 10ft x 12ft = 1,200 cubic feet
  • 1,200 cubic feet of air X 20 changes per hour = 24,000 cubic feet of air to change per hour
  • 24,000 cubic feet/hour ÷ 60 minutes/hour = 400 cubic feet per minute

In this case, we could specify a Model 6042 2″ Aluminum Adjustable Air Amplifier, which uses just 21.5 SCFM @80psig to generate a total developed flow of 430 SCFM (see table above). Minus the 21.5 SCFM of compressed air flow, that means it’s drawing 408.5 SCFM in from the tank.

If additional airflow is required, the ring gap of the Adjustable Air Amplifier can be easily increased by threading the plug out of the body until the needed flow is achieved. A Pressure Regulator can also be used to ‘fine tune’ the compressed air supply, and hence, the ventilation flow.

EXAIR Air Amplifiers are a simple, low-cost way to move air, smoke, fumes, and even light materials. If you’d like to find out more, or if you have a potential application to discuss, give me a call.

Russ Bowman, CCASS

Application Engineer
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