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Combustible Dust - Hazards / Mitigations / Pitfalls

  • Type:
    Conference Presentation
  • Conference Type:
    AIChE Spring Meeting and Global Congress on Process Safety
  • Presentation Date:
    April 2, 2019
  • Duration:
    30 minutes
  • Skill Level:
  • PDHs:

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Combustible dust is and has been a major issue in industry. This is not something new but is something that is more in the spotlight in recent years with accidents being taken seriously, incidents being published publicly and legislation coming into effect. People and companies need to understand the hazards of combustible dust. What are the threats to your industry, to your facility and to the lives of your employees? There are several stark examples of incidents related to combustible dust that will be examined. This presentation will touch on the causes, as well as the effects of the incidents.

In addition to understanding that there is a hazard, and what this hazard may present, people need to understand how this specifically relates to their facility. There will be discussion time to better understand how you know if you have a dust issue or what can be done to determine if there is an issue. This will include dust sampling (how to collect it, where to collect it, when to collect it), dust testing and understanding the results. There are several tests that can be done to not only determine if your facility has a problem but the extent that problem can present. Once the dust has been analyzed, will you understand the results and what they mean to the facility?

Once a facility knows it has combustible dust, how is it addressed? What are some of the things that can be done to minimize the potential for an issue (fire, explosion, etc)? We will discuss housekeeping, electrical classifications as well as dust collection systems. In addition the discussion will mention the Dust Hazard Analysis (DHA) and how they can be completed.

Combustible Dust – what is it?

Combustible dust is defined as a solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition, which presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations.

Given the proper circumstances combustible dust can have extreme consequences.

Case Study 1 – Imperial Sugar: What happened? How did combustible dust play a role in this deadly explosion?

Case Study 2 – West Pharmaceuticals What happened? How did combustible dust play a role in this deadly explosion?

Review dust explosion statistics.

For a majority of explosions there is a fire or explosion

Sampling & Testing

Knowing its dangerous is one thing but a facility must also determine what its level of risk is. This involves sampling and testing. In order to sample for combustible dust it is recommended to get a representative sample but keep it to an given area – milling room, not ground floor.

There are several tests that can be performed. If you want to know if you have a problem but not how severe the problem may be, you can start with Sieve Test which tests the distribution of dust sizes. In addition to this test there is a Go/No Go test that will only determine if a sample is combustible not the extent. If these test show there is a combustible dust issue then other tests will determine the extent of the hazard. These include KST, Pmax, MEC, LOC, MIE, MIT.

Once a facility knows it has a combustible dust issue and the extent of that issue, what should be done.

  1. Housekeeping
  2. Electrical Classification
  3. Dust Collectors
    1. How do you know if your dust collector is compliant?

Dust Hazard Analysis (DHA)

DHA’s where initially supposed to be completed as of 2018 but, as of now, are required to be completed as of 2021. What is a DHA? It is similar in style ad focus to a standard Process Hazard Analysis but with an emphasis on dust.

HAZOP is still a viable approach

Checklist / What-if are commonly used

Common Pitfalls when dealing with Combustible dust

  1. Status quo
  2. Not performing a Risk Assessment
    1. As mentioned earlier they will be required by 2021
    2. You should know your risks before then
  3. You get what you pay for.
    1. Bargain equipment
    2. Used equipment
  4. Housekeeping
    1. Lack of a documented program and frequency
    2. Lack of adherence to housekeeping
  5. Buying the Cadillac but not knowing how to drive it or what it does.
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