Fire Risks

 

Fires and Explosions

Fires and Explosions

What can cause a fire or an explosion?


Three elements are needed to cause a fire or an explosion:

Oxygen

For combustion to take place, the oxygen content needs to be above 11%. Our normal atmosphere consists of 21% oxygen. This means that the oxygen element is always present.

Inflammable material

Most material that has been transformed into fine particles can burn or explode. Every year, many serious fires and explosions occur in industrial plants as a result of an ignition of combustible dust.

Ignition source

When handling combustible material it is very common that ignition sources, often caused by friction heat, are generated from equipment within the process. Worn parts as well as foreign objects (stones, nails, nuts, etc.) can also increase the risk of generating ignition sources. Not only visible sparks but also hot particles, at temperatures down to around 250°C/480°F, can start a fire or an explosion.

 

Risk Assessment

RISK ASSESSMENT

How dangerous is your process?

If you handle combustible material, as for example combustible dust, the following aspects need to be taken into consideration:

• Identify your risk zones. 

Examples of risk zones

cyklonfilterchute

• Identify your Ignition Source Generators (ISG) 

Examples of ISG’s

• What is the oxygen level? The oxygen content needs to be above 11% for combustion to take place.

Turbulence; if there is less turbulence in the environment, the fire risk is higher.

• Find the Minimum Ignition Temperature (MIT) for the material in your process. (see table)

• Find the Minimum Ignition Energy (MIE) for the material in your process. (see table)

• Is the dust concentrated in a layer or in a cloud? In general, dust in a layer ignites at lower temperatures than in a cloud. (see table)

Minimum Ignition Temperature and Energy level

 

Cloud  

Cloud  

Layer 

Layer 

Min. Cloud 
Ignition Energy.J 

 

°C 

°F

°C 

°F

 

Wood 470 878 260  500  0,04 
Weat Flour  440  824  440  824  0,06 
Cellulose  480  896  270  518  0,08 
Sugar  370  698 400  608  0,03 
Cocoa  510  950  240  464  0,10 
Aluminum  610  1130  326  619  0,01 
Coffee  720  1328  270  518  0,16 

Souce: NFPA (National Fire Protection Association)


• What is the particle size and shape? In general, smaller particles ignite more easily and are more explosive.

• What is the moisture content of the material in your process? In general, a dryer material means a higher risk of fire.

• What are your process-specific parameters, i.e. amount of material, transport speed, duct diameter, chute size, etc.?

• Do you have high-risk machinery that need protection (flame detection and water mist suppression)?

Solutions

Solutions

How can you avoid fires and explosions in your process?

Experience and research* show that the key to minimising production downtime and damage due to fire and dust explosions is the detection and elimination of potential ignition sources, i.e. sparks and hot particles.

Firefly provides unique and patented technology based on True Infrared (IR) radiation detection and full cone water spray extinguishing with the purpose to detect and extinguish both sparks and hot particles in industrial processes. Firefly also offers flame detection and water mist suppression around high-risk process machinery.

A Firefly protection solution is always tailor-made and based on a risk assessment of your specific process.

* National Fire Protection Association (NFPA) / Prof. Rolf K. Eckhoff ”Dust explosions in the process industries” / Bundesanstalt für Materialforschung und -Prüfung (BAM)

 

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