St 1 dust - Dangerous or not?

Hope all of you readers are doing well. It is the time of Diwali here in India and everywhere one can see people in the festival mood. Be careful and safe & have a wonderful Diwali.

Today I am trying to clear another misconception which I have come across while talking about St 1 dust. Many of our clients have told me that we are handling St 1 dust which is also the so-called "WEAK EXPLOSION" hence the risk is low. 

I always give them the example of Imperial Sugar Explosion in 2008 where a St 1 Sugar dust lead to 14 fatalities or Didion Milling Co. explosion in 2017 where St 1 grain dust was to blame for 5 fatalities, a dozen injuries and $1.8 million fine.

Combustible dusts are ranked into one of four classes i.e. St 0, St 1, St 2 and St 3. The level of explosion violence increases as we go from St 0 to St 3. The only dust that has zero risks of the explosion is a St 0 dust. However, all other dusts have an explosion hazard including the St 1 dust which can compromise containment on a piece of equipment, or blow out the walls of a building. Grains, Sugar, Fluor, etc. all fall in St class 1 dust.

Housekeeping and Secondary Dust Explosions

Thanks for such brilliant response to my past blog on Relief Sizing. It really feels satisfying when it gives food for thought to people about their own plants. It is a much wider subject, hence all of us can hold different opinions on what is already there in terms of regulations and what is practically being done at the grass root level. In the end, my objective is simple and that is to make the community aware of some process safety aspects which can help them make their operations safer.

For this blog, I will be discussing the importance of housekeeping to prevent Dust Explosion or should I say Secondary Dust Explosions.

How many companies out there still utilise compressed air for cleaning of equipment surfaces and to blow off the settled dust from surface/ floor/ clothing?

How many of them still dry broom dust settled on the shop floor?

How many of you still don't know that the powder which is settled on equipment surface, shop floor, electrical fitting, etc., is combustible in nature and can result in fire/ explosion hazard in the plant?

How many of your plants have false ceilings and that hidden area is not being reviewed for any powder accumulation?

How many of you still use non-rated vacuum cleaners in plant areas to remove the spilt dust?