Plant Equipment and Hire May 2019 | Page 31

SAFETY PREVENT YOUR EXCAVATOR FROM GOING UP IN SMOKE! Aside from the safety features built into modern excavators themselves, ASP Fire can assist mining operations in mitigating this risk, which has a major implication for productivity and the bottom line. The design and installation of a vehicle fire protection system requires that mining vehicles are subjected to a hazard identification and risk assessment (HIRA) of potential fires, ASP Fire CEO Michael van Niekerk explains. Each vehicle needs to be assessed carefully within its specific operating environment, to understand what hazards and fire risks a vehicle is exposed to. During the assessment, the inherent fire risks in the vehicle are identified, such as the turbo chargers and the brake system, which could overheat, as well as high-pressure hydraulic systems and electrical equipment that may ignite a combustible or flammable component of the vehicle. Such assessments run the gamut, from excavators to haul trucks and even draglines. ASP Fire designs systems to suit individual vehicles and their specific requirements. This means examining the conditions not only inside the vehicle, but also within the surrounding environment. Although dry chemical powder (DCP) extinguishers are highly effective in firefighting, they offer minimal cooling properties. This results in re-ignition of flames, especially in liquid fuel and rubber fires, thereby increasing the risk of property damage and loss of life. The powder inside DCP extinguishers can also compact due to vibration when placed on a moving vehicle. This compacted powder increases the risk of malfunction when activated. As a result, DCP extinguishers placed on mobile equipment need to be serviced more frequently, Van Niekerk highlights. DCP extinguishers also pose serious operator and environmental hazards. When used in confined spaces, they can affect the fire respondents’ visibility and capability to effectively suppress the fire, or to safely evacuate an area should the fire grow out of control. www.plantonline.co.za Mining vehicles such as excavators are high-value assets operating under harsh conditions where there is an inherent danger of a fire breaking out. Inherent fire risks such as turbo chargers and the brake system overheating, or high- pressure hydraulic systems and electrical equipment that may ignite combustible or flammable components of the vehicle, are assessed to assist mining operations to mitigate risk. A much more effective and ‘greener’ solution is a range of water-mist special risk and handheld fire extinguishers distributed by ASP Fire. Using water as the main agent and nitrogen as a propellant, this handheld range is capable of extinguishing most types of fires, including rubber and plastic, diesel and petrol fires, and electrical fires rated up to 245kV. The atomised mist generated by the extinguisher increases the surface area of the water by more than a hundredfold. These micro-droplets turn rapidly into cold steam when coming into contact with burning or very hot materials, further increasing the surface area by 1 600 times. The endothermic reaction of water converting to steam, rapidly and effectively cools down any hot surfaces in the immediate environment. This not only extinguishes the fire, but cools down hot spots, without any thermal shock. It also creates a thermal heat radiation barrier between the operator and the fire, allowing the operator to get close to the fire without the risk of getting burnt when operating the extinguisher. The system also includes a protection mechanism to eliminate any false alarms. This consists of a heat-sensitive pressurised activation tube that requires heat to rupture and open a differential valve on the main cylinder to activate the system. In addition to pure water-based systems for use inside the operator’s cab, ASP Fire also uses an aqueous film forming foam (AFFF) solution, which provides superior fire extinguishing and vapour suppression for hydrocarbon fuel fires. The AFFF blanket blocks oxygen supply to the fuel, and cools any hot flammable liquid by effectively sealing the surface. “It is essential to undertake pre- shift and weekly inspections on mining vehicles that operate in demanding environments to ensure that the fire system is in working order. During the inspection, the technician needs to check that the nozzles are still attached correctly, covering the high-risk areas effectively; that the blow-off caps are still on; and that there is sufficient pressure in the detection line and in the system,” concludes Van Niekerk. MAY 2019 29