EXAIR Corporation’s Research & Development team often finds themselves at odds with our Marketing department, who thinks R&D, through their constant introduction of new ideas & products, is trying to turn our catalog into something resembling a phone book.
I do not believe that is their aim or intention, though (and to be fair, Marketing doesn’t either.) Honestly, we just want to help folks in a wide range of industries solve problems. And a diverse range of engineered compressed air products is our tried-and-true, successful method for doing so.
There are a great many applications that require a spray (as opposed to a stream) of liquid. Certain droplet sizes, and flow rates, are beneficial for certain applications. For example, if you’re fighting a fire, you want as high of a flow rate as possible – the more water you douse the fire with, the quicker it goes out. You also want a fairly large droplet size, since a mist would tend to evaporate instead of extinguishing the flames.
Pressure washers also benefit from higher (though not near as high as fire hose) flow rates, and droplet sizes. You want an appreciable flow rate, because that means high velocity, and good sized droplets combine that velocity with their relative mass to “blast” away dirt and detritus from the surface.
Medicine delivery devices, like asthma inhalers, are designed to produce mid-sized droplets, but pretty low (and controlled) flows. The droplets need to be small enough to efficiently spread the medicine through the breathing passages, but large enough to where they won’t evaporate before they ‘plant’ on the nasal & bronchial membranes to get absorbed.
These are examples of “liquid-only” nozzles…no other media or means of force are used to effect the spraying action. Most of the time, the droplet sizes in these applications are measured in hundreds of microns, which “liquid-only” nozzles are ideally suited to generate. Other applications, however, call for much smaller droplet sizes…such as those only attainable through atomization.
Small droplet size is key to cost effectiveness in many applications:
Think about expensive coatings…the smaller the droplet size, the better and more even the coverage, and the less you have to spray (and pay) out.
Or humidification…smaller droplet size means more stays airborne, for longer, and in a larger space.
Petroleum based lubricants, by their nature, only require a thin layer for best results. Smaller droplets make as even and thin of a layer as possible.
Dust control is much more effective with smaller droplet sizes, since the longer the mist lingers in the air, the more dust particles the individual droplets will adhere to…and then drop with them to the surface. This also prevents getting the surface of the material any wetter than it has to be.
If you’d like to discuss a liquid spraying application, I’d love to hear from you. Call me.
Russ Bowman Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
The image above shows a material transfer process for starch. At the top of the tower the starch rests inside of tumbling tanks (shown below) which blend larger pieces into small, finely blended particles. In order to achieve the proper blend, an hydration level of 5% water must be maintained within the tank. For the water introduced to the tank, the smaller the droplet size of the water particles, the better the blend. The current setup in this application is to spray water directly into the tanks, by hand, using a pump sprayer.
The investigation into droplet sizes led this customer to EXAIR Atomizing Nozzles, searching for a method to introduce small droplet water particles into the blending tanks. The ultimate question was “How small of a particle size can we achieve with an EXAIR Atomizing Nozzle?”
The answer to that question can be found here on our website and in our catalog as well. Our smallest confirmed droplet size is currently 22µm when using our 1/4″ NPT Siphon Fed Atomizing Nozzles, which was more than enough for this application.
By installing SR1010SS atomizing nozzles into this application this customer is able to achieve the required hydration level with small droplet size water particles. These particles ensure proper blending of the starch and proper quality for the final product. And, the atomizing nozzles prevent an operator from having to manually add the necessary water to achieve the required hydration in the blending tanks.
If you have a solution in need of an atomized liquid solution, contact an EXAIR Application Engineer. We’re here to help.
Recently, I was working with a customer that has purchased several of the EXAIR Atomizing Spray Nozzles, specifically the model Aw5020SS. The customer had another project coming up and needed two more nozzles. I inquired about the application and we discussed at length the way the nozzles are being used.
When a concrete road is being poured, several sample forms are poured during the process. The local Department of Transportation takes the samples and cures them in a wet room for 30 days, and then performs tensile testing, to confirm the concrete meets the strength requirements. The wet room must be kept at 23°C (73.4°F) and 100% Humidity during this time frame. The EXAIR model AW5020SS Atomizing Nozzles are used to provide the moisture that ensures the room humidity conditions are met and maintained. Because the droplets are very fine, the effect of a fog is achieved, with the water droplets suspended in the air, keeping the humidity at 100%.
Atomizing spray nozzles are capable of producing very fine droplet sizes. A typical rain drop is 6000 microns in diameter, standard liquid nozzles produce droplets ranging from 300-4000 microns. The EXAIR Atomizing Nozzles produce droplets from 20-100 microns!
Droplet sizes can be adjusted by varying either the liquid pressure or air pressure. Increasing the air or decreasing the liquid pressure will generally produce a smaller droplet size.
EXAIR manufactures (3) types of Atomizing Nozzles – Internal Mix, External Mix, and Siphon Fed, in both 1/4 NPT and 1/2 NPT sizes. Maximum liquid viscosity is 800 cP. Flow rates range from 0.6 GPH up to 303 GPH, so we’ll be able to find one that meets your flow requirements.
To discuss your application and how an EXAIR Atomizing Nozzle can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.