Winter is only a little over a week away and already snow and ice have caused issues in the south. As I continue to listen to the news about the winter storm conditions, I can’t help but think about how the cold weather creates an increase in dust explosions.
As you may already know, over time, dust created from the manufacturing process begins to accumulate on the surfaces of machinery, ceiling rafters, floor and even in the ductwork. The empty space of the building is full of oxygen, which provides fuel for a fire to burn. The constant movement of air from the machinery, using compressed air, or even from smaller fires or explosions nearby disrupts the dust and disperses it into a dust cloud. Since the dust cloud is being contained by the walls of the building, an ignition source is created (usually from heat, or sparks) within reach of the cloud, which ignites and causes an explosion.
So what is it about the cold weather that makes it more likely for a combustible dust explosion to occur?
Lack of Ventilation
When the heating system is running during the winter the occupants of the building will be sure to keep doors and windows closed to conserve this heat. In warmer weather these bay doors or building windows might be opened to let in fresh air, or there will be fans running to maintain airflow inside the building. This extra airflow can keep dust levels from becoming too high to become hazardous, but the lack of extra ventilation in the winter can let dust levels increase.
Low Humidity Levels
The cold winter air means humidity levels are lower than in warmer months because cold air holds less moisture in it than the warmer air. If a building uses a forced air heating system it makes the air humidity even lower by causing any remaining water vapor to burn out. Lower humidity levels dries out the accumulated dust, which makes it easier for these dusts to disperse throughout the air, and can lower the temperature required for ignition.
Many common housekeeping practices in manufacturing facilities rely on water, but when temperatures drop too low cleaning with water can’t be used. Depending on the facility, cleaning practices also tend to be slowed down or done more infrequently when it’s cold outside. This causes either the dust to accumulate until warmer weather when water-based cleaning can be used again, or other cleaning techniques that can be dangerous for combustible dust are used. Typically, people will use compressed air to clean dust in an area that was previously using water for cleaning. However, this just results in a dust cloud, creating a dangerous situation for everyone involved.