The oldest and most often used method of dust control is the use of wet spray systems. As the dust particles become wet the weight increases, thus decreasing its ability to become airborne. As groups of particles become heavier, it becomes more difficult for the surrounding air to carry them off. The keys to effective wet spray dust control are proper application of moisture, careful nozzle location, controlling droplet size, choosing the best spray pattern, and proper maintenance of equipment. International fog Inc (IFI) patented spray technology is in a unique position to offer a nozzle with extended coverage areas, specified droplet size, even water distribution, various spray patterns, and easy maintenance. IFI nozzles use a patented rotor technology that maintains droplet momentum, provides a even spray distribution, and shears the water for smaller droplet sizes at lower pressures. Although the use of water sprays is a very simple technique, there are a number of factors that should be evaluated to determine the most effective design for a particular application. Airborne dust prevention is achieved by direct spraying to prevent dust from becoming airborne. Airborne dust suppression involves knocking down dust already airborne by spraying the dust cloud and causing the particles to collide, agglomerate, and fall out from the air. Each dust type and application point is a unique situation and needs to be evaluated separately to achieve the optimal design.
The amount and uniformity of wetting is an important issue for an effective system. IFI offers a number of spray patterns and k-factors to suit your application. Customized nozzles can quickly be produced to suit a given application. For more information please contact us.
Controlling Droplet Size
When using sprays, one of the primary considerations is the droplet size. If the droplet diameter is much greater than the diameter of the dust particle, the dust particle simply follows the air stream around the droplet. If the water droplet is of a size comparable to that of the dust particle, contact occurs as the dust particle collides with the droplet
For optimal agglomeration, the particle and water droplet sizes should be roughly equivalent. The probability of impaction also increases as the size of the water spray droplets decreases. IFI Nozzles provide a range of droplet sizes to suit your application. Droplet size ranges include:
Methods of Atomization
Atomization is the process of generating droplets by forcing liquid through a nozzle. International Fog uses Hydraulic or airless atomization that controls droplet size by forcing the liquid through a known orifice diameter at a specific pressure. This is a less expensive method because it does not require compressed air. In addition, significantly less water pressure can be used because IFI's patented technology also uses a shearing force to break up the water creating smaller droplets. Water additives, that break the surface tension, can be added to produce even smaller droplet sizes.
Chemical Additives to Control Droplets
Surfactants are sometimes used in wet spray applications because they lower the surface tension of the water solution, which has the following effects: reduced droplet diameter; an increase in the number of droplets for a given volume of water; and a decrease in the contact angle, defined as the angle at which a liquid meets a solid surface.
The use of surfactants increases the rate at which the droplets are able to wet or coat dust particles; thus less moisture is used to produce the same effects as a typical water application.
Small amounts of surfactants can be injected into the spray water, typically in a dilution range of 1:700 to 1:1500, to improve the wetting and subsequent control of dust particles.
NOZZLE TYPES AND SPRAY PATTERNS
IFI nozzles are configured to produce full cone, hollow cone, and round spray patterns. Rotor configurations include Sphere, D and A rotors with each having a specific application. The A rotors provide Full Cone, Hollow Cone, and Round Spray patterns. The D Rotor can produce a full cone and throw coverage in the forward direction. The Sphere provides a 360 degree spray pattern for total volume coverage. Please contact us for more information and if you have questions about your application.