Protection series – How to protect against fire

– How to protect yourself and your equipment against fire

We can be amused for hours by fire in a controlled environment. For some, it goes by the name campfire. But under uncontrolled circumstances, it is one of the most feared and respected elements of nature, and the risk has to be considered concerning the safety of people, the environment, and the integrity of structures.

Fire is hot, but fire safety is not. We disagree. And here’s why…

How can a fire start?

Three elements required for a fire are sufficient oxygen, a combustible source, and a heat/ignition source. It is also important to note that some chemical reactions can form oxygen and can keep burning even while being submerged in water, an example of this can be Li-ion batteries (Ref. https://www.ffi.no/aktuelt/nyheter/li-ion-batteries-hazards-and-mitigation).

Combustible sources

  • Combustible gas
  • Combustible materials
  • Combustible dust

Ignition sources

  • Faults in electrical installations (E.g. poorly connected socket)
  • Heat or sparks (E.g. arc created by fuses or sparks created by machinery)
  • Chemical reactions (e.g. poorly separated reactive substances)
  • Static electricity, (e.g. a risk especially at, Gas plants or sawmills, (dust clouds))

 

What are some of the risks related to fire?

  • Deadly Heat – Increased heat due to fire is lethal and can spread the fire by materials self-igniting at a distance, even material on the other side of no combustible walls.
  • Explosions – combustible materials, liquid, and gasses, exposed to fire can explode, burn and contribute to spreading the fire.
  • Smoke and gas – Fire consumes oxygen around and produces toxic gas which can give short-term and long-term health issues and of course, asphyxiation and death. Gas and smoke are the most common reasons for respiration failure during fires in households and can have fatal results if no immediate respiration support is given (ref. https://eprints.whiterose.ac.uk/96795/).

 

How to protect and control fire?

  • Passive fire protection – Used as a shield against fire, and is achieved by using noncombustible materials which limits the heat transfer, normally specified by a limited time frame, typically 15-240 minutes. The main purpose of the protection is to reduce the speed at which the fire spreads and ensure, sufficient time for evacuation, protection of critical systems, and prevention of structural failures. Check out this interesting article on the subject of passive fire protection which references the terrible Grenfell tower fire accident.

Fire has different intensities depending on the fuel and hence, different resistance classes. Commonly used for external barriers in the oil and gas industries are A60, H120, and J30 (where A is the lowest and J is the highest intensity).

Figure 1: Fire test curves, Pink Hydrocarbon fire, and Purple cellulose fire.

 

For onshore application resistance class EI60, which is one the most commonly used and represents a typically cellulose fire (organic material). E stands for integrity, I, for insulation, and 60, for 60 minutes. During a test according to the curves shown above, the temperature on the opposite side of the fire shall not exceed 140 (180 at spots) degrees Celsius <60min (ref. NS-EN 13501-1:2018). Similar regulations apply for the oil and gas classes, but tests are done according to IMO FTP Code.

 

Source – SINTEF

  • Active fire protection – Used to extinguish and/or control the Fire. This is usually achieved by having a medium on standby that will activate automatically or manually, in the event of a fire and extinguish or control the fire. Commonly known methods are water and water mist, but also other mediums are used depending on the location and source of the fire. Other extinguishing mediums can be different types of foams, powder, or inert gasses.

 

  • Fire retardant materials – Used to reduce the spread of fire, smoke, and toxic gases. To control the potential risk there are often set requirements as to which type of material to be used based on reaction to fire. One of the commonly used classifications for onshore applications is tested according to NS-EN 13501-1:2018. The material could typically be classified with this notation, A1-S1, d0 where:
    • A1 means non-combustible material. (classified from A1-F, where F has a high contribution to fire)
    • S1 means little or no smoke released during combustion (range from S1-S3)
    • D0 means no droplets from the material during combustion (range from d0-d2)

Check out Uniteam’s fire-protected buildings here

 

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