Dust Control With Fog - Just One of the Many Uses of Fog

Fog - microscopic sized water droplets suspended in the air - is finding favour in a broad range of applications. It may not be a panacea for everything but it is proving highly useful in numerous areas, one of which is dust control.

Misting Droplet

Many industrial processes generate dust. Once airborne, this will hang in the air for hours and can be breathed in by operatives, pollute the process and clog equipment.

Fog works as a dust suppressant due to the small droplet size. This is a similar size to the dust particle, enabling the two to stick together when they collide. Typically, several dust particles adhere to the water droplet. As a result, the overall weight of the agglomerate becomes large enough to fall out of the air, removing the respirable airborne dust with it.

MicronFog™ dust control solutions can be arranged in different ways. For processes with known dust sources, nozzles can be placed around the source and in certain cases can drop the dust back into the process.

In other applications, for instance warehousing, a more general dust control arrangement can be configured at roof height. Any airborne dust is then captured and dropped to the floor.

There is often concern about wetting the product, but MicronFog™ has been used successfully on dry powder bagging lines and potato and onion packing. In each of these applications, it is essential that product remains dry. If not, the product becomes unsellable.

At present, there is a Government public education campaign about COPD (Chronic Obstructive Pulmonary Disease). Whilst smoking is a cause of this, breathing in workplace dust is another common cause.

There are already regulations in place limiting exposure to silica dust to 0.1 mg/m3. There is discussion about reducing this further to 0.05 mg/m3. Fog has been used as a successful dust control method to bring the levels below this tighter requirement, and it will be an essential tool to meet the stricter legislation.

Fog Safety

Legionnaire’s Disease is another important consideration: if a system does not pay full attention to this then avoid the system at all costs. It may be cheap in the short term, but who wants to be the one to explain to a family that they have lost a loved one as a result of saving a little bit of money?

As the water droplet size is so small, it and whatever it contains can easily enter the body. Therefore, it is essential that the water used in the fog is extra safe.

To this end, we insist that mains potable water is used as a supply and then take the supplemental step of further disinfection using ultra violet light. This is interlocked with the system control, which prevents the system from operating if the UV lamp is not functioning or has reached the end of its life.

Humidification and Cooling

Rapid Assembly Fog nozzle with fog close up

Rapid Assembly Fog Line

The Renby MicronFog™ system finds many uses both in and out of industry. The initial objective was to use it for suppressing dust. As experience with the technology has increased, a whole host of other uses have materialised in previously undreamt-of applications, such as humidification or as a cooling system.

Another effect that occurs with fog is flash evaporation. Once again, due to the small droplet size, the fog droplet can rapidly evaporate into the air. As the flash evaporation occurs, there is a corresponding drop in temperature. In a building, this can occur after a few minutes, but it has also been observed within seconds on a ducted system.

For instance, when a fan is used to force air into a process, the compression can cause the air to increase in temperature. By introducing fog downstream of the fan, cooling will occur due to flash evaporation. We have observed temperature drops from 40˚C to 25˚C within seconds on process air.

Food Cultivation

Exotic Mushrooms Grown with MicronFog

Exotic Mushrooms Grown with MicronFogTM

For food cultivation, the control of humidity is an essential ingredient for promoting crop growth. MicronFog™ replaced a low pressure spray system that was humidifying a group of polytunnels used for mushroom growing.

Not only was the result a more precise control of humidity levels but it also reduced water usage as the older technique was wasteful. When required, the system can be expanded to measure and control the humidity in each tunnel. This versatile function enables the system to provide precise humidity levels in each tunnel, responding to the crop requirements at each stage of the growth cycle.

Landscape and Architectural

Whilst not strictly an industrial process, the versatility of the system is such that it can produce great effects for art installations and sculptures. The ability to switch fog on and off at will facilitates the design of a whole new area of kinetic sculptures providing an immersive experience to visitors.

The system has been used to provide effects ranging from banks of fog for visitors at a tropical rainforest attraction to atmospheric effects for film sets. The image shows a kinetic sculpture designed by a leading UK sculptress, renowned for some of Europe’s largest kinetic sculptures.

Kinetic Sculpture with fog

Kinetic Sculpture with MicronFogTM

To discuss how MicronFog™ systems can be used in dust control, cooling, architectural or any other application, please fill in our contact form today, or call us on 01829 740913.