What is Spray Atomization?

Tank washing systems, fire deluge equipment, and pollution control units all require the use of spray nozzles that offer water droplets in varying sizes and spray patterns. These spray sizes and patterns allow for the even distribution of water and other liquids to interact with the applications as well as environmental conditions. Spray atomization is a type of spray nozzle process used to break up water droplets into a very fine mist.

What is Spray Atomization?

Spray atomization is a nozzle engineering design where compressed air or gas becomes intermixed with water at a specific high pressure to produce fine and very fine water droplets of the same size. This design is always for increased control of propelled water droplets over a specific area, environment, or onto equipment.

Atomization spray nozzles come in different designs based on where the water and air/gas become combined. These systems can be used for a variety of purposes including from spray coating to odor control.

How Do Atomized Spray Systems Work?

Spray nozzles will have three ports. Two outer ports are used to eject compressed air and gas. The third inner port ejects the water or other liquid medium. With these ports close to each other, the water becomes mixed with the air due to the nozzle's tip design. This tip design also allows the atomization spray in a specific spray character, such as flat, full cone, or hollow cone, by using either a metering screw, needle value, or a pneumatic pressure regulator.

The entire atomization spray system consists of adjustment devices, tubing, nozzle valve, a fluid supply system, and a compressed air/gas system. This equipment allows for the intermixing of water and air in two distinct methods: internal mixing and external mixing.

Internal mixing consists of the water and air/gas becoming mixed inside the nozzle. Then the mixture is ejected from the tip as a very fine atomized mist for liquids that do not exceed a rate of 200 centipoise (viscosity valve of liquids). A lower rate of centipoise for the liquid allows for it to flow very easily and at a fast rate from the nozzle and to the application as an atomized spray of very small droplets. To control the liquid rate, the air pressure is adjusted to specific measurements.

External mixing involves the water and air/gas to become mixed outside of the nozzle at the tip. The ports are not connected inside the nozzle. When the air and water mix, the atomized spray creates small droplets that are larger in size than when this process is done by internal mixing. Liquids with a viscosity valve of over 200 centipoises can be effectively atomized using this spray mixing method. While the droplet sizes are larger, external mixing provides greater control of the water and compressed gas.

Selecting between internal mixing and external mixing will be based on a variety of factors. Some of these factors include the viscosity of the liquid, the applied pressure, the type of ejected fluid, and the flow rate. You can also use the size of the desired droplets and the application to decide on the mixing method to use. Whichever method is used, both systems allow for the air and water to mix while having little to no water to collect at the nozzle tip and drip down, which can become a safety hazard in the workspace or can cause damage to the application.

Types of Atomization Systems

Two types of atomization systems are pneumatic atomization and hydraulic atomization. Hydraulic atomizers rely on a single tube filled with water that then ejects that water from the nozzle tip to mix with the air outside. Also called single fluid nozzles, these systems work with liquids that have very little viscosity. The liquid passes through the atomization system at an increased speed (velocity) based on the nozzle becoming smaller in its design along its cross-section. This velocity and ejection of liquids can create droplets of varying sizes due to the aerodynamic wave pattern.

Pneumatic atomization may also be called twin fluid atomization. This method is used for more viscous liquids as it involves the mixing of the water and compressed gas. Pneumatic atomizers are available as both internal mixing and external mixing processes. They can create the finest spray droplets for applications.

For spray dry absorption (SPD), some companies rely on rotary atomizers. Rotary atomizers work by using a rotary wheel, cup, or disk that rotates at high speeds to eject the liquid as a spray. In many instances, this method is becoming replaced with dual fluid air atomizer spray nozzles for better reliability, more consistent droplet sizes, and reduced maintenance costs.

Types of Nozzles Involved

The nozzle types used for spray atomization will be based on the application and the desired spray pattern. Some types include pneumatic atomization nozzles, hollow cone spray nozzles, full cone spray nozzles, flat fan spray nozzles, punctual/plane compressed air dispersion, rotating nozzles, and static spray balls.

Pneumatic atomization nozzles come as both flat spray and full cone nozzles. Flat spray nozzles can produce angles at 80 degrees while full cone nozzles circular spray patterns from 20 degrees to 30 degrees for narrow full cones. Larger full cone sizes can be designed using special multi-orifices.

Hollow cone spray nozzles are available as axial-flow or eccentric-flow that causes the liquid to rotate either using swirl insets (axial flow) or a tangentially positioned liquid supply (eccentric flow). Axial flow nozzles may also be called hydraulic nozzles.

Full cone nozzles may also come as axial flow, or as tangential flow. Tangential flow does not come with inserts as the nozzles have grooves milled into the tip. This reduces the likelihood of clogging. Full cone nozzles create coarser droplet sizes.

Flat fan cone nozzles may come with or without a deflector plate. A flat fan pattern is created at a distance from the nozzle as the liquid disintegrates into a finer mist based on this distance.

Plane/punctual dispersion are used for dispersing air or steam. The nozzles can produce a flat fan pattern or a solid stream pattern.

Rotating nozzles and static spray balls are commonly used for tank cleaning/washing purposes. The nozzles can be used for lower pressures for repetitive cleaning applications.

What Industries are Atomized Spray Solutions For?

Atomized spray nozzles solutions can be used for various industries depending on the application. These nozzles are commonly used for coatings, humidification, odor control, mixing, lubrication, and dust control. Some industries that may use these nozzles include manufacturing, chemical, food & beverage, petrochemical, pharmaceutical, and marine operations.

Why Choose Lechler's Atomization Spray Products?

Clients select Lechler's spray atomization nozzles and systems due to their high quality materials, range of spray patterns and methods, and customizations. Our nozzles can be specially engineered to work with existing spraying systems and applications to integrate with workstations. Whether you are working with a specific fluid, flow rate, or pressure, we can design the nozzle to accommodate your needs. Contact us today.