Can Passive Fire Protection play a role in the Li-Ion EV fire risk space?
Michael Simpson
Experienced EXCOM Leader & Veteran | Making a Difference in the Building Materials Industry
As the Australian government pushes forward with incentives encouraging ownership. How do we protect a structures against fire caused by Li-Ion thermal runaway at the charging zone?
The development of the EV sector and the construction of new charging points and stations require a a better understanding to guarantee the safe storage and charging of electric vehicles in underground and multi-story carparking structures, especially in terms of fire and life safety.
Should enhanced fire protection of the super structure be considered as part of the overall fire safety strategy? What is the balance between both passive and active fire protection measures needed? Does this includes the upgrading of passive fire protection for concrete and steel structures?
Whilst LiBESS (Lithium-Ion Battery Energy Storage Systems) EV fires appear for now to have a similar or lower incident rate than traditional ICE (internal Combustion Engine) vehicles. The complexity for first responders in dealing with an EV fire is greater.
Research by EV FireSafe has shown around 25% of EV fire to date have occurred in underground/enclosed spaces, with around 30% of all fires occurring during charging:
Intervention and suppression by fire combat agencies may take longer due to the hazards posed to first responders that need to be isolated or dealt with including: potential live electrical risks, vapour cloud explosions (deflagration), toxic gases and jet flames (>2000DegC):
In case of thermal runaway, the traction battery needs to be cooled in an attempt to slow and stop the chemical reaction continuing. The extinguishing process can take several hours, 4000 - 30,000L of water, and there is also a risk of reignition up to 20 hours later. Complicating this process is the location of the traction batteries in most EV vehicles. These are located on the floor of the car so application of water is extremely difficult at the best of times. This potentially means the building structure would be subject to longer and more intense fire exposure risks.
So then, if upgrading the superstructure is required by the project authorities or consultants. How does one achieve the addition fire protection to the structure itself? What needs to be considered for the type of material needing to be upgraded?
How to Protect the Loadbearing Structure
When a fire breaks out, it is crucial that we give the occupants of a building enough time to evacuate to a safe place and allow the fire fighters to combat the fire. This is why we need to prevent the building from progressive collapse, even isolated collapse, during a fire.
If we can avoid the (partial) collapse of the building, we will be able to limit the damage to the building as well as the assets contained in it. In some cases, the content of a building represents special, irreplaceable value. Just think of the objects with historic or emotional value you find in a museum or library. Or the life saving equipment that is used in a hospital. The damage goes far beyond a financial loss.
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Structural Steel Protection
When steel heats up during a fire, the structure gradually loses its loadbearing capacity at temperatures between 350C and 750C. Depending on the loads and actions on the structure, it would typically fail when the steel reaches temperatures between 500 and 600C. Therefore, structural steel protection is required to preserve the stability of the building structure in the event of fire. Promat offers a wide range of board, spray and paint products to suit the requirements for any project.
Structural Concrete Protection
When concrete heats up during fire, at some point in time the steel reinforcement will heat up as well. The heating of the steel reinforcement is delayed by the concrete cover, since the thermal transfer through the concrete is relatively slow. Moreover, at temperatures in a range of roughly 200-800C the concrete itself loses its loadbearing capacity because of internal micro-cracking and chemical transformation (dehydration) of the cement phase. Typically, design standards simplify this gradual strength loss by assuming a limiting temperature of 500C for concrete.
For concrete structures in low-humidity environments and exposed to the standard (cellulosic) fire curve, most design codes accept that spalling will not occur. In case of more severe fire curves or exposure to humid environments, spalling of concrete could lead to the loss of cover within a short time, and this could result in an additional more stringent temperature requirement for the concrete surface itself, rather than for the steel reinforcement bar that is placed inside the concrete.
Structural Protection Solutions
Promat offers a full range of PROMATECT board and CAFCO spray products providing flexible solutions to meet a variety of installation and fire protection needs for most common construction materials. These system work by slowing the transfer of heat into the structures extending their time to reach critical interface temperatures. Promat can assist with providing standard test evidence or development of performance solutions with your project fire engineer. In house Finite Element Analysis (FEA) for concrete beams and structures can help assist with baseline protection thickness required.
Promat products and systems have been tested and/or certified at accredited laboratories to a variety of standards such as AS1530.4, AS4100 & AS3600. Should protection against more onerous heating regimes (hydrocarbon) be required, then please consult Promat to ensure the correct evidence and certification is provided to you.
It appears a large volume of study and research is going on via various bodies including Fire and Rescue NSW (SARET Research), Fire Protection Association Australia (FPA Australia) (Li-Ion Battery Special Interest Group), Australian Building Codes Board (Provisions for EV charging) and many universities around the world. Hopefully in time we will better understand the risks and dangers and our National Construction Code can adapt in time to address these new risks. The move to EV vehicles is coming and hopefully we get the regulation correct to mitigate another construction code oversight disaster, like we have seen in recent years.
Senior Forensic & Construction Expert at Self-employed
1 年The real heat and dangers emanating from Electric charged cars and the amount of water needed is far greater ??than in this early write-up non the less it's a well-written informative warning thanks for Sharing And remember EV cars are like a Bomb ?? in waiting ??
Associate - Fire Services Lead at Compass-Intelle Engineering Group
2 年Dr Than Sharma Aayush Sharma
CEM PgDip QS, Dip BS, Grad DipBS (Giga Project)
2 年It was interesting reading a piece today where a chap purchased a Tesla car. He wanted to install the charger in the car park in the basement. I’m following all with interest in what I need to be aware of for my role at work. But it amazes me that this guy had to pay $5000 bucks to purchase a 99 year lease to be able to charge his car. This was to run the charging point from his Electrical meter in his apartment down through the service shafts to the basement where his car would sit at night. It took months and had to be approved by strata with 50 owners giving the nod. I guess strata contracts and purchase contracts for new build apartment will have to allow for all this and charge accordingly. BCA direction is needed to be updated quickly by industry.
Views expressed are my own, NOT my employers!
2 年Trip hazard city. Slips trip and falls everywhere, not thought out at all.
retired from providing APFS services - but still publisher & editor technical publications and advisor re building services & compliance
2 年Agree that passive encasement of structural elements is worthwhile and needed, however, other issues also are equally needed: gas detectors specific to offgassing which alert and shut down charger supply as well as toxic gas extraction systems at high and low levels, plus extinguishing and smothering agents delivered either automatically or readily accessible portable ride extinguishers.