Understanding Air Entrainment or Amplification Ratios and Air Knives

Super Air Knife has 40:1 Amplification Ratio, entrainment is illustrated as the curved blue arrows.

EXAIR’s Super Air Knife is the top performer among our engineered air knives and it dramatically reduces compressed air usage and noise when compared to other blow-off systems. The Super Air Knife delivers a uniform sheet of laminar airflow across the entire length of the air knife. Even at high pressure of 80 PSIG (5.5 BAR), the sound level is surprisingly quiet at 69 dBA for most applications.

One feature of the Super Air Knife is its Amplification Ratio, or the ratio of ambient air to compressed air within the forceful blast of air from the Super Air Knife. The design of the Super Air Knife entrains ambient air at an amplification ratio of 40:1 (ambient air to compressed air). Entrainment is defined in the simplest of terms as: to draw in and transport (something, such as solid particles or gas) by the flow of a fluid. The Super Air Knife design produces two low pressure areas where surrounding air is pulled into the primary compressed air stream and is delivered to your target. EXAIR’s Intelligent Compressed Air® products use the principle of entrainment to give you more air volume than just the compressed air being introduced from your air compressor.  This will maximize the force value for your application with the minimum amount of compressed air. Any pipe, manifold, or fitting can be modified to blow compressed air, however, these homemade blow offs will be very noisy and perform poorly when it comes to air entrainment, or amplification ratios. In contrast EXAIR’s intelligent compressed air solutions are engineered to be very quiet and use conservative amount’s of compressed air while maximizing the output volume through entrainment. 

Furthermore, the table below demonstrates the differences between blow-off systems and the efficiency of EXAIR’s Super Air Knife. You can see that the Super Air Knife outperforms all or most other options when comparing purchase price, sound level, maintenance, horsepower required and electrical costs.

The use of EXAIR’s Super Air knife not only save air consumption but you can notice the lower decibel rating which meets or exceeds OSHA Standard 29 CFR-1910.95(a) for maximum allowable noise exposure. If you have questions or need help with EXAIR’s Super Air Knife or any of our Intelligent Compressed Air Products please contact us and let us help you.

Eric Kuhnash
Application Engineer
E-mail: EricKuhnash@exair.com
Twitter: Twitter: @EXAIR_EK

5 Important Factors When Selecting an Atomizing Spray Nozzle

The most recent EXAIR Webinar is up and ready to be viewed as an on demand video. This presentation showcases five important factors when selecting an atomizing spray nozzle. Throughout the webinar you will gain several key takeaways that are outside of the five factors as well. If you have a liquid spray application and are not sure where to start, this video has a wealth of information for you. As always, the Application Engineer department is also here and ready to assist as needed. We can walk through any application with you and help right over the phone, through email, or even live chat.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Liquid Spray Nozzles Improve Gummy Candy Production

One of the more popular treats for kids and adults are gummies.  They can be sweet, sour, and in different shapes and colors.  A candy company that makes gummy bears was looking for a better way to spray food-grade oil onto their product.  They contacted EXAIR about our Air Atomizing Spray Nozzles. 

We discussed their setup and process for making the gummy candies; or in this case gummy bears.  The sugary mixture is poured into molds that are coated with corn starch.  The corn starch helps to keep the gummy from sticking to the mold.  Once hardened, the bears will be released from the molds and travel through a stainless-steel spinning drum.  In here, they apply a light food-grade oil onto the bears.  This process will hide the starch and give the candy that glazed and colored feature.  The drum was near 60” (1.52 meters) long and spun at 19 RPM.  The gummy bears would tumble along the length of the drum at a designed production rate of 2000 Kg/hr. (4,400 Lbs./hr.).  They used drip tubes along the top to apply the food-grade oil onto the gummy bears.  They noticed that the color was not as good and the coverage was spotty.  The oil pump was metered in a range of 0.35 – 3 gal/hr. (1.32 – 11.3 l/h).  The temperature inside the drum could reach up to 150oF (65oC), and the viscosity of the food-grade oil ranged between 190 – 400 cps.  In order to get the best results for quality, they had to reduce their production rates to about 1,700 to 1,800 Kg/hr. 

To determine the correct solution, we had to dive a bit more into their application.  The details of the EXAIR Atomizing Nozzles are measured with water as the liquid.  Since they are using an oil at different temperatures, the specific gravity will change slightly.  For their oil, the specific gravity is 0.92 at 20oC and 0.89 at 65oC.  We can use Equation 1 to convert the required flow rate from the food-grade oil to water.

Equation 1:

Q1 = Q2 * SQRT (SG2 / SG1)

Q1 – Flow of water (gph)

Q2 – Flow of oil (gph)

SG1 – Specific Gravity of water

SG2 – Specific Gravity of oil

The Specific Gravity of water is 1.  With the range of specific gravity for the oil, we can calculate the range that is needed as indicated by water.  Then we can make a selection as referenced by our data in the catalog.  Since we want to make sure that we can cover the range of the metered oil pump, we will use the maximum flow rate of 3 gph.  In adding the values, we get the following:

@20oC  Q1 = 3 gph * sqrt(0.92) = 2.88 gph

@65oC  Q1 = 3 gph * sqrt(0.89) = 2.83 gph  

Since the viscosity ranges above 300 cps., I recommended the External Mix Atomizing Nozzles to be mounted along the length of the rotating drum.  The External Mix can handle viscous liquids up to 800 cps.  Unlike the drip method, the EXAIR Liquid Atomizing Spray Nozzles use compressed air to shear the oil into small droplets and to disperse the oil in a wide pattern.  With the smaller particle size, we can get more coverage area which will allow them to use less food-grade oil.  The coverage area on the gummy bears was near 15” (38cm) as they rolled down the drum.  I also recommended the No-Drip option to allow for versatility in their process.  The No-Drip option for the Atomizing Nozzles is a very nice option which will stop the liquid solution from dripping when not in use.  When they needed to apply the oil, they would just turn on the compressed air to the Atomizing Nozzle.  It made it very easy to control.  This was important to reduce excess usage and non-conforming parts. It also keeps the inside of the drum oil free during cleaning cycles.   

EB2010SS

From the data above, I recommended three pieces of the model EB2010SS, No Drip External Mix Wide Angle Flat Fan Pattern.  The spray pattern was 14” (35.6cm) wide to cover part of the 60” (1.52m) length of the drum.  With an estimated 1 gph for each nozzle, we would be able to spray the maximum requirement as calculated above (2.88 gph).  After installation, they were able to get a consistent deep color of the gummy bear at the maximum production rate of 2,000 Kg/hr.  They also noticed that with the fine particle spray, they were able to use less oil.  With the three pieces of the model EB2010SS, they were able to reach maximum production rates with less food-grade oil and reduce scrap rates.

If you have a liquid that you would like to spray evenly, efficiently, and effectively; EXAIR Atomizing Nozzles can do that for you.  You can contact an Application Engineer for help.  For the customer above, they were able to create those gummy treats for kids and adults.  Yummy.

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

Picture: Giant Gummy Bear by Alexas_FotosPixabay licence.

EXAIR Siphon Fed Air Atomizing Liquid Spray Nozzles

Amongst EXAIR’s continuously growing product offering, some of the newest are a family of Air Atomizing Liquid Spray Nozzles that does not require a pressurized liquid source. These are known as the Siphon Fed Air Atomizing Nozzles. These nozzles can be easily implemented where a tank can be installed and lower the cost of the installation by not requiring a liquid pump, just point of use compressed air.

Siphon Fed model

This action is done by the unique design of the air cap.  As the velocity of the air passes through the air cap, low pressure is created by a venturi.  The Siphon Fed Atomizing Nozzles can draw liquid from a suction height of 36” (91 cm), or gravity fed. They are manufactured from 303 stainless steel for durability and corrosion resistance. The Siphon Fed models can spray viscous fluids up to 200 centipoises and are used in many applications like rinsing, coating, cooling, quenching, humidification, or dust control. The images below showcases how simple the setup can be for the siphon and gravity fed installations.

EXAIR Siphon Fed Nozzles work with non-pressurized liquids, either siphoned (left) or gravity fed (right.)

EXAIR carries three different body sizes, 1/8” NPT, ¼” NPT, and ½” NPT ports; so, you can create a light mist or a heavy spray of liquid.  The maximum liquid flow rate is controlled by the air cap and liquid cap combination.  A unique feature of the EXAIR Atomizing Nozzle is that the caps are easily interchangeable for each body size to modify the spray patterns, control the amount of fluid, and reduce any downtime if cleaning is required.  The video below shows just how easily the changeover is done.

In addition to the three different inlet/body sizes, we also offer the Siphon Fed in both a round spray pattern or a flat fan spray pattern. These are also controlled by the air and liquid cap combination. This means it is easy to convert a round pattern that may be needed for a job, over to a flat fan pattern for the next setup. Each pattern is also available in several flow rates of liquid and air to dial in the performance required by the application.

Siphon Fed Air Atomizing Spray Nozzles

Additionally, if you would like to positively shut the liquid flow off from the nozzle in order to prevent drips, over use of liquid, or to shut off the gravity fed liquid when not needed, the No-Drip versions of these nozzles is also available. This is easily controlled by simply reducing the compressed air operating pressure to below the designated cracking pressure of the patented No-Drip valve.

No Drip Siphon Fed Round Pattern Atomizing Nozzle

If you would like to discuss which spray nozzle is best suited for your application, please reach out to an Application Engineer.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF