When applying liquids to surfaces, sometimes a fine coating is desired to ensure full coverage while also minimizing product waste. Spray nozzles are used to apply the liquid in a process called air atomization. Many industries rely on air atomizing techniques for their products or equipment when manual application done by hand is not efficient or may be dangerous. Learn more about air atomizing processes and spray patterns.
What is Air Atomizing?
Air atomization is when air or gas is added to liquid to create a fine mist. This mixing of the air and liquid may be done within the nozzle itself or directly outside the nozzle opening. Called two-fluid nozzles, these nozzles have a liquid feed line and an air/gas feed line inside the nozzle. How they are mixed will depend on whether the nozzle is designed for internal mixing or external mixing.
Internal mixing nozzles have an air/gas feed, liquid feed, liquid cap, fluid cap, and an annular area where the spray will emit from the nozzle. Both the liquid feed and the air/gas feed meet inside the annular area, where everything mixes together. Then the mixture leaves the annular area in the desired spray pattern depending on the nozzle design. In this design, both feeds are dependent on each other. Any changes made to the air pressure will directly impact the liquid flow. Internal mixing nozzles are commonly used for liquids that have a lower absolute viscosity (centipoise or cP) rate of under 200.
External mixing nozzles do not have an annular area. Instead, while the liquid and air travels through their feeds, both exit out of separate openings at the end of the nozzle. There may be more than one aperture for the air/gas to exit from the nozzle, such as one opening directly beside the liquid aperture and a second opening further out. Since both feeds are kept separate, the flow rates for the air and liquid can be independently adjusted without impacting each other. This design allows for more precise fluid metering. An external mixing nozzle can handle most fluids in addition to viscous fluids that have more than a 200 cP rate.
Air atomizing nozzles can create very fine and small droplets even when using lower pressures. They are ideal for applications where the liquid must be applied or used with a single nozzle in an even coating quickly without nozzle clogs and at very thinness.
Industry Applications for Air Atomizing
Air atomizing nozzles can be used in various industries based on the application. The nozzles can be used to apply liquids as coatings, or for humidifying, gas cooling, lubrication, fogging, and other applications.
Coatings applications are common for product manufacturing industries such as food, automotive, pharmaceutical, and other companies. They may apply edible color coatings to medication, paints on cars and consumer products, as well as coatings on surfaces that may come in direct or indirect contact with food.
Humidifying applications involve the use of air atomization to push out moisture into the air. This extra moisture may prevent things from drying out or becoming damaged. A common humidifying application would involve a greenhouse area where spray mist is applied to plants to water them as well as to clean dust off leaves. Humidifying air atomizing nozzles may also be seen along produce aisles in grocery stores where the mist keeps vegetables fresh and prevents leaves from wilting.
Companies operating equipment may rely on air atomizing methods to lubricate working parts to decrease wear and tear, eliminate friction, and prevent damage to components. These air atomizing nozzles can be used for hard-to-reach areas of places where it would be dangerous for workers to apply the lubricant by hand.
Some industries that produce large amounts of airborne dust or dirt during operations. To improve the air quality and prevent the dust or dirt from entering processes or damaging products and equipment, air atomizing nozzles may emit vapor in the form of fog into the space. When the airborne dust or dirt comes into contact with the fog, it adheres to the droplets and becomes heavy enough to fall to the ground.
Companies may create objects that are required to be cooled down before they are further processed, or equipment that needs to be cooled after experiencing high temperatures. Air atomizing nozzles can cool down objects, equipment, and even gasses for operations.
Industries from product manufacturing to food may use atomizing nozzles for cleaning and sanitizing purposes. For example, beverage companies may use air atomizing nozzles to clean bottles before liquid products are poured inside.
Best Spray Nozzles for Air Atomizing
When selecting air nozzles, keep in mind the required flow rates desired for both the liquid and the air/gas. Also, determine the droplet size and where the liquid tank setup that will feed into the nozzle. If the liquid supply tank is located at a higher level as gravity will be used to push the liquid through the nozzle, then Lechler pneumatic air atomizing nozzles can be designed to accommodate this setup. In other instances, the liquid supply may be under pressure, which would require high flow pressure nozzles.
Spray pattern also plays an important role when it comes to spray nozzle selection. If you are going to apply paint coatings or food toppings, then a flat fan nozzle is appropriate. If circular coverage is required or liquids will be injected into a pipe, a full cone nozzle type is preferred.
Lastly, consider the viscosity of the liquid. For low viscosity liquids such as water, Lechler's AirMists nozzles fine atomized sprays. For very viscous liquids such as syrups or thick oils, lecher ViscoMists nozzles can provide even coatings without clogging. For more information regarding our air atomizing systems, contact us today.