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Best practices for selecting onboard fire suppression systems for heavy-duty mining vehicles

Heavy-duty mining vehicles operate for long periods across harsh, rugged environments and require reliable onboard fire protection to help protect people, equipment and the business continuity of the mine. However, as mining vehicles continue to become larger, more powerful and more complex, their fire hazards have changed, too. Most mining vehicles have multiple fire hazards that could require application-specific fire protection solutions. By protecting each hazard with the appropriate on board fire suppression system, the damage to the equipment is limited and operator safety is improved in the event of a fire, Kristin Ryczek* says.

When selecting hazard-specific onboard fire suppression, it’s important to consider several factors for best results. Here are six best practices to follow:

1. Understand the fire risks that are present

The first step to selecting onboard fire suppression systems is understanding the specific fire risks on mining equipment. By clearly understanding the risks that are present, mining companies can equip their vehicles with the most effective fire suppression solution for each fire risk. Electrical hazards, for example, necessitate a different approach to fire suppression than what is required for engine compartments.

The engine compartments in many of today’s mining vehicles contain turbocharger exhaust manifolds and emission packages, as well as diesel fuel sources, hydraulic fluid and other class B fuels. The engine components are likely to have high surface temperatures that can create an ignition source. For engine component protection, it’s important to seek a solution that can cool superheated surfaces while providing comprehensive suppression capabilities. Using the right solution makes fire suppression efforts more effective while minimising the risk of reignition.

Powered cables can also be an ignition source for the hydrocarbons that are within the engine and hydraulics if not properly maintained. However, electrical equipment, which is often stored inside unoccupied cabinets, requires different fire suppression considerations. This equipment is often more sensitive than engine compartments, and failure due to fire or smoldering can lead to significant operational disruptions. For this application, it’s often best to consider an electrically non-conductive clean agent solution designed to suppress fire without damaging electronics. Clean agent systems will often use a nitrogen agent, which requires no clean-up and has a zero global warming potential (0 GWP), making it a good option for equipment and the planet.

2. Consider single-agent vs. dual-agent solutions

For several decades, heavy mining vehicles have depended on dual-agent fire protection systems for their engine compartments. As the name suggests, dual-agent (or twin-agent) systems use both dry chemical and liquid agents in a single design. The dry chemical agent rapidly knocks down flames, and the liquid agent cools hot surfaces and minimises reflash potential. However, the suppression benefits these dual-agent configurations provide come with additional complexity – including costly clean-up and repairs after a dry chemical discharge, careful planning for side-by-side installations and the need to activate two separate systems simultaneously.

These challenges emphasise the need for new fire suppression solutions that simplify fire protection while meeting the needs of today’s heavy-duty industrial vehicle operations. While some mining vehicle applications require twin-agent systems to meet the NFPA 120 and 122 standards, the latest single-agent systems hold FM approval and are suitable for many applications. Single-agent systems can streamline the complexities of dual-agent systems, and some superior single-agent options can even provide higher-performing and more cost-effective fire protection for mining vehicles than traditional dual-agent systems.

3. Look for solutions designed specifically for your needs

When protecting multiple vehicle hazards with unique fire suppression needs, it’s important to choose solutions that have been designed specifically for those applications. Application-specific design helps ensure more effective system performance and efficient installation and maintenance. This is especially relevant in the mining industry where products need to be built to withstand long hours in extremely harsh conditions. Effective fire suppression system design is achieved through a deep understanding of the risks, the assets being protected and the ideal amount of agent that needs to be discharged onto the hazard.

When protecting engine compartments, application-specific fire suppression solutions can offer increased operational flexibility and simplicity. This is due in part to recent liquid single-agent advancements that allow each nozzle to cover more area – up to 54 in (137 mm) – compared with previous dual-agent solutions. This extended spray distance helps the agent flow into hard-to-reach areas where flammable liquids may have migrated. It also allows end users to select and install the ideal number of nozzles for their applications. Fewer nozzles generally mean less installation and maintenance needs for the end user. That’s because less nozzles mean less hose network to route through the hazard. Less agent and less tanks also mean less weight added to the vehicle for overall efficiency.

There are also benefits to selecting an application-specific fire suppression solution for electrical enclosures. Some nitrogen-based systems designed for mining vehicles don’t require many of the safety devices that a carbon dioxide system would require, including time delays and lockouts. This translates into less components to install and maintain. Some nitrogen-based systems also have a wide temperature operating range to withstand extreme conditions. Users should look for solutions with an operating range of -65° F to plus 210° F (-54°C to plus 99°C) and with a rugged design to help ensure effective use in the harshest environments.

4. Look for solutions that have been rigorously tested and/or hold third-party approvals

When it comes to fire suppression in extreme mining environments, bold claims are not enough. It is critical that fire suppression agents for mining vehicles are backed by rigorous testing and third-party approvals, such as FM approval.

Johnson Controls recently conducted extensive testing to prove effectiveness of a new, non-fluorinated single-agent liquid system. The company wanted to prove it can prevent reflash by quickly knocking down flames, blanketing the fuel and cutting off oxygen without the addition of a dry chemical agent. The team evaluated the new agent (ANSUL® LVS NF-40) against some of the leading single-agent and twin-agent setups currently used in the industry.

The testing results confirm the standalone performance of the new liquid agent. It demonstrates the speed at which the new liquid agent can extinguish high-pressure fuel sprays and fuel in-depth pool fires while also cooling the entire mass of the plate and the fuel in-depth pan below. Additionally, the new liquid agent had a lower discharge time than the tested legacy liquid agent, which demonstrated that less of the new liquid single agent is required for effective fire suppression.

5. Consider regulations and standards, as well as environmental impacts and sustainability

In many industries, including mining, regulations are shifting around the use of per- and polyfluoroalkyl substances (PFAS). Because of these changes, the mining industry is moving toward non-fluorinated fire suppression solutions for mining vehicles. When selecting a non-fluorinated onboard solution for effective Class A and B fire suppression on mobile mining equipment, it is important to choose a non-fluorinated agent that offers performance equal to or better than previous formulations.

NFPA 122, the standard for fire prevention and control in metal and non-metal mining and metal mineral processing, requires the use of a twin-agent suppression system in ultra- and mega-class mining equipment with hydraulic systems containing more than 150 gallons (682 litres) in the lines. However, there are now single-agent fire suppression systems that have been tested and received FM 5970 approval to perform just as well as twin-agent systems.

While NFPA standards are often used as guidance for enforcement of the required fire suppression by Authorities Having Jurisdiction (AHJ), they aren’t always the only accepted method for providing fire suppression. Standards like NFPA often take time to update and change as the market and available solutions evolve. A white paper from Johnson Controls provides supporting data and evidence that could be used by an installer or end user making the case to a notified body to accept an effective single-agent system over the twin-agent system that NFPA suggests. As such, an installer or end user could apply an FM 5970-approved single-agent system, acknowledging the need for conversation with any AHJ to approve the installed system. As the fire industry progresses, it’s possible that standards will update and become aligned with newer, more fit-for-purpose solutions.

For electrical compartments in mining vehicles, it’s important to source a clean agent that meets stringent government regulations surrounding chemical agents. From an environmental and regulatory standpoint, a nitrogen-based clean agent may be preferable over clean agents with a chemical formulation and can simplify compliance processes. Nitrogen has been a popular clean agent gaseous suppression option for many years, since it is a naturally occurring atmospheric gas and does not fall under restrictive regulatory measures. Furthermore, it is also easier to source dry nitrogen for a system recharge than other gas mixtures used in similar clean agent systems.

6. Keep clean-up in mind

A fire event isn’t actually over until your vehicles get back up and running. Clean agents offer a significant advantage over traditional agents when it comes to post-suppression clean-up, especially for electrical compartments densely packed with sensitive controls. Traditional agents that are not electrically conductive, like dry chemical, can effectively extinguish fires, but they can leave residue that requires extensive cleanup and can affect the electrical components. In comparison, a clean suppression agent leaves no residue, helping to minimise clean-up and maintain the integrity and operation of intricate electrical systems.

Similarly, in engine compartments, single-agent liquid systems typically require less cleanup than single-agent dry-chem or dual-agent systems. Less cleanup can save time and help operations resume more quickly after activation.

Best practices for the best protection

Onboard fire suppression systems are ideal for heavy mobile mining equipment because they provide continual, 24/7 protection as vehicles move across mining sites. By following these best practices, installers and users can select the most effective onboard fire suppression system for each fire risk. Correctly specified fire suppression solutions help prevent equipment damage, protect personnel and prioritise sustainability while keeping operations moving into a safe, profitable future.

*Kristin Ryczek is Global Vehicle Product Manager for Johnson Controls

Nitrogen tyres and oxygen generators bring safety and sustainability to mines

David Cheeseman*, Chief Engineer of Oxair Gas Systems, believes the mining industry should take on board the latest on-site gas generation technology to help improve safety and reduce its carbon footprint.

The mining industry is becoming a lot more technology-focused, with advancements in autonomous mining technology and automated surface vehicles, as the industry presses ahead to reduce carbon emissions and boost safety in mining.

The International Council on Mining & Metals’ (ICMM) Innovation for Cleaner, Safer Vehicles (ICSV) initiative – a supply chain collaboration with original equipment manufacturers (OEM) – is to be applauded. However, in the meantime, rugged terrain will still be taking its toll on the tyres of mining vehicles, which are the workhorses of the extraction process.

These trucks operate in harsh environments and extremes of temperatures, which is why nitrogen-filled tyres are ideal, because they remain inflated for longer and are more resistant to hot climates and freezing at high altitudes, making them safer for operators and site staff alike. Unlike compressed air, nitrogen is an inert gas that does not react with other materials, so it is resistant to corrosion and, therefore, provides an extra tier of safety where critical applications are involved.

It is imperative that tyres are fully inflated to reduce the risk of critical air leaks and rapid deflation when the vehicles are under pressure. But being at the mercy of the supply chain for bottled nitrogen, especially in extreme locations where conditions are challenging, is costly. Nitrogen can be difficult to transport, not to mention the additional carbon footprint of delivery vehicles and safety risks for staff manually moving cylinders from one place to another, especially with the new threat of contamination posed by the coronavirus pandemic.

However, companies can avoid the hassle of having to outsource their gas from conventional cylinders by switching to an on-tap supply through a nitrogen generator. A nitrogen generator on site is the ideal alternative choice to manhandling canisters for heavy-duty equipment where precise or constant pressure is vital.

Oxair’s nitrogen generators are efficient and compact, making them an ideal solution for mining sites. They offer a continuous flow of gas extracted from the atmosphere and are an environmentally friendlier method of delivery, as they reduce the carbon footprint associated with having

Oxair’s nitrogen generators are efficient and compact, making them an ideal solution for mining sites, David Cheeseman says

cylinders transported from an off-site facility and then the return journey when they are empty.

Nitrogen generators are cheap to run and, once installed, require minimal maintenance. Nitrogen plants are built to last and are operator friendly, making them crucial where tyres need to perform well in a remote location or challenging environment.

As with all high-quality engineering solutions, nitrogen generators can be tailored exactly to suit an individual mine’s requirements. They can be designed for outdoor or covered facilities and, as well as offering low energy consumption, a supplier should be able to provide on-site training to enable local employees to properly calibrate and easily maintain the system once it is operational, as well as full ongoing maintenance support.

Some of the world’s leading gold mining companies are already seeing the benefits of gas on tap at sites rather than taking deliveries of traditional cylinders. Pressure Swing Adsorption (PSA) oxygen equipment supplied by Oxair is helping AngloGold Ashanti extract more of the precious metal from one of its flagship gold mines, potentially extending the life of the open-pit operation in Tanzania.

Two booster processors for increasing oxygen pressure and two oxygen generator tonnage plants to further improve the efficiency of the leaching process are in operation at AngloGold’s Geita Gold Mine, enhancing gold recoveries and protecting the environment by reducing cyanide consumption.

This equipment is helping to increase production and extend the mine’s lifespan beyond 2025, when it was originally set for closure. The state-of-the-art equipment supplied, which includes upgraded control systems, will double the reliable source of pure oxygen for the future activities planned at Geita. It will mean significant efficiencies in carbon in the leach technology method of gold recovery and should help the mine be both economically and environmentally sound for its extended lifespan.

Using oxygen generators significantly improves the gold dissolution process through adding highly purified oxygen at the slurry stage of leaching. Mined rock is usually ground up and turned into a slurry by adding lime, cyanide, oxygen and water before being fed through a carbon bed to extract the gold. Incorporating highly purified oxygen allows cyanide to work more efficiently and, thus, reduces the quantity of cyanide needed in the process.

A PSA tonnage plant takes oxygen directly from the air using on average of only 3 kW of electricity per 100 cu.ft of oxygen produced and transforms it into highly purified oxygen by removing nitrogen entrainments (which are useless to the leaching process).

Using oxygen generators significantly improves the gold dissolution process through adding highly purified oxygen at the slurry stage of leaching

Oxygen tonnage plants are designed for on-site applications requiring large amounts of oxygen, such as mining, with outdoor or covered standard installations – PSA equipment is bringing numerous advantages to the mining industry, as well as eliminating the need for expensive and unreliable deliveries of liquid or cylinder oxygen.

On-site generators provide mines with a turnkey solution for getting a constant, reliable source of high-quality oxygen and nitrogen where it is needed. It is clear that with responsible mining practices geared up for long-term sustainability, investments in quality equipment will be key to achieving both safety and sustainability goals.

*This piece was written by David Cheeseman, Chief Engineer of Oxair Gas Systems. Oxair is an ISO 9001 certified company focused on the design and manufacture of packaged oxygen PSA Systems, as well as Nitrogen PSA systems up to 1,000 Nm3/h.