greg staple - south australian metropolitan fire service - combustible dust from an emergency...

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

Firefighting:

Building and system

constructions? and

Fire science?

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

Recent MFS events:

April 1998

Dust explosions

Recent MFS events:

Dust explosions

Dust explosions

In summary

Sept 2010

Operational Overview.

Aerial view of storage area

Sept 2010

NORTH

By the nature of the information available -

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

Recent MFS events:

February 2012,

Fire origin area

February 2012

Area affected by fire

Smoke staining of windows

Fire affected area

February 2012

Dust explosions

Recent MFS events:

Feed mill

March 2012,

Dust explosions

March 2012

March 2012

Critical fire ground factors –

Overview

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

Were there Risks of a Dust Explosion at any of these events?

ABSOLUTELY YES

Dust Explosions

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


Types of events.

Process fires:

Dust Explosions


Dust Explosions

Storage fires:

Fires in storage devices for the finished or primary products.


Oxygen limiting, closed or semi-closed

Open

Dust Explosions


Oxygen limiting, closed or semi-closed

Dust Explosions

Regional Communications

Common Silo arrangement

Product entry or inspection point




Air space




Air space

Stored product




Air space

Stored product

Discharge point



Product entry or inspection

point

Air space

Stored product

Discharge point

Ignition source

Ignition source

Result



point

Air space

Stored product

Discharge point

Ignition source


What now occurs?

Dust Explosions


point

CO

Stored product

Discharge point

Ignition source


As the product moves, dust may evolve

Dust Explosions


point

CO

Stored product

Discharge point

Ignition source


This dust, in the right concentrations, may rapidly and

violently ignite (Flash Fire)

Dust Explosions

dust


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


Failure?

Where could Firefighters be conducting fire

suppression activities?

Dust Explosions


Dust Explosions Imperial sugar 2008

Storage containers:

Open

Dust Explosions


Open or Oxygen limiting? How can we know?

or

Dust Explosions


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


Dust Explosions

The ignition source has probably already been established prior to our

arrival,

Stakeholder expectations?

Putting the fire out.

Dust Explosions

Subjectively, all fire go out,

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

Measures

Flammability

Measuring a precursor to a dust explosion

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

Thank you,

Any questions?

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