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Dust Explosions From an Emergency Services perspective.
Date of issue: April 14
Document number: DEx 3.5
Version number: 2.0
Review Date: April 15
Authorised by: Commander Greg Staple
South Australian Metropolitan Fire Service (MFS)
Dust Explosions Conference:
The AIM of this presentation: Is to discuss my experiences of fires in organic
dust storage and process facilities from an Emergency Services perspective, including:
Case studies and the broad MFS Investigations
Emergency Service personnel Expectations and
Assumptions
Dust Explosions
Recent MFS events:
April 1998 - Grain storage Facility fire.
September 2010 - Grain storage facility fire.
February 2012 - Grain storage facility fire.
March 2012 - Feed mill processing facility fire.
Dust explosions
Summary
The Front End Loader stopped directly under a skylight (approximately 15metres above).
The skylight failed
Construction
Fires impact
Firefighting
Plan:
Dust explosions
What was our plan? The Strategy. The Intel.
The Outcome.
This was very time consuming to
undertake safely
Feed mill approx. layout:
Dust explosions
Feed mill, fire origin
Screw conveyor
Elevator
Slide
Storage Silo
Feed mill:
Dust explosions
Feed mill, fire origin
Screw conveyor
Elevator
Slide
Storage Silo
The Screw Conveyor – was fire damaged
The Elevator – was fire damaged
The silo was approximately 2/3 full of fine dusty organic material
With the aid of thermal imaging – the external surface of the silo was 150 degrees Celsius, at about 2/3 up
from the bottom
Feed mill:
Dust explosions
Fire
A large problem was that, this silo was connected to others via the top and also, via the discharge devices, dust collection devices and duct work, which
resulted in a shared air space
Duct work, which is shared to Various parts of plant
Feed mill:
Dust explosions
Fire
Duct work, which is shared to Various parts of plant
This potentially enabled a pathway for any products of combustion to be dispersed to other areas, OR
IF, An event was to occur in the fire
effected container (explosion), this could be shared by other plant and
vessels with catastrophic consequences
Feed mill:
Dust explosions
What was our plan? Initially it was to undertake a defensive position and
monitor the temperatures within the silo Fortunately management was on hand and remained
so as an extremely valuable reference and information source
Once established that the fire was contained only to the silo, a plan was established to remove the product
This was very difficult and time consuming to undertake safely, discuss
From a Firefighting perspective:
What risks exist?
There a Five conditions for a Dust explosion.
1. Fuel
2. Oxygen
3. Confinement
4. Ventilation and the ability to suspend and mix, and
5. IGNITION SOURCES
Dust Explosions
Explosive environments:
Of the five elements considered for an explosive environment,
IGNITION SOURCES are the most likely that a Firefighter may
initially control.
Remove Ignition sources:
A Fire Service is at the event probably as a result of a fire or a known risk of fire.
Therefore, there potentially has been or still is an ignition
source.
Investigate:
Any Fire Service should seek as much information as possible prior to developing an action plan which
involves a crews tactical deployment.
General Firefighting activities:
Removal of the ignition source will reduce the risk!
With the right conditions
A primary and then possibly a secondary explosion may occur.
Situational Awareness
We should NEVER assume that a initial event has removed the possibility of a
further flash fire or explosion.
Dust Explosions
Practical Firefighting Risks:
Fire Services attendance
Is the present situation a potential precursor to a flash fire or a deflagration?
Dust Explosions
Practical Firefighting Risks:
Dust Explosions
Storage fires:
Fires in storage devices for the finished or primary products.
Regional Communications
Common Silo arrangement
Product entry or inspection point
Air space
Stored product
Regional Communications
Common Silo arrangement
Product entry or inspection point
Air space
Stored product
Discharge point
Regional Communications
Common Silo arrangement
Product entry or inspection
point
Air space
Stored product
Discharge point
Ignition source
Ignition source
Result
Common Silo arrangement
Product entry or inspection
point
Air space
Stored product
Discharge point
Ignition source
Practical Firefighting Risks:
What now occurs?
Dust Explosions
Product entry or inspection
point
CO
Stored product
Discharge point
Ignition source
Practical Firefighting Risks:
As the product moves, dust may evolve
Dust Explosions
Product entry or inspection
point
CO
Stored product
Discharge point
Ignition source
Practical Firefighting Risks:
This dust, in the right concentrations, may rapidly and
violently ignite (Flash Fire)
Dust Explosions
dust
Practical Firefighting Risks:
This will dramatically increase the pressure within the container.
This pressure could force the container to fail at the weakest
point
This inadvertently will create more dust adding to the fuel load
Dust Explosions
Ignited dust
Practical Firefighting Risks:
Failure?
Where could Firefighters be conducting fire
suppression activities?
Dust Explosions
Practical Firefighting Risks:
There are numerous possibilities for ignition sources with all installations
Friction
Mechanical or electrical failure
Chemical reaction
Human error
Lighting strikes
Foreign objects
Etc etc
Dust Explosions
Practical Firefighting Risks:
Dust Explosions
The ignition source has probably already been established prior to our
arrival,
Stakeholder expectations?
Technically, the fire service has been called to the event to
mitigate the risks!
Dust Explosions
There is an expectation that we will put the fire out and make the area safe.
Tactical solutions
All Fire Services understand the principals of dynamic risk
assessments,
particularly risk vs benefit.
Dust Explosions
Tactical Solutions
Approach Consequences Comparisons
Regardless, in the right conditions the initial consequences can be similar.
Dust Explosions
Tactical Solutions
Firefighter safety will always be paramount.
Heavy consultation to industry experts
Dust Explosions
Tactical Solutions
Any Fire Services Tactical plans will always provide a safe exit
pathway and effective exposure controls.
Dust Explosions