Three Elements are Needed to Cause a Fire or an Explosion
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.
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.
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.
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:
- Identify your Ignition Source Generators (ISG)
Examples of ISGs
- 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 temperature (celsius) Cloud temperature (fahrenheit) Layer temperature (celsius) Layer temperature (fahrenheit) Min. Cloud Ignition Energy Wood 470 878 260 500 0,04 Wheat 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
- 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)?
How Can You Avoid Fires & 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”