Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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FIRE SAFETY Mining machines can require hundreds or even thousands of pounds of fire suppression agent and ancillary equipment to provide complete fire protection. Shown here is an AFEX Systems fire suppression installation on a large bulldozer. Typically, fire suppression systems are bought and installed after the equipment sale, either through a dealer/distributor or directly by the mine. In recent years, Stromberg noted, equipment OEMs have begun consulting more frequently with system vendors "to make their equipment more fire-suppression ready. Some of the larger equipment types carry thousands of pounds of fire suppressant in tanks. We're working with a major haul truck OEM, for example, to help them design deck layouts and support to accommodate these systems." The gamut of fire-protection packages includes pressurized dry-chemical systems, newer stand-alone aqueous-agent (liquid) systems that provide enhanced fire-suppression performance over broader temperature ranges, and twin-agent systems that combine dry and liquid agents. Each type of agent has specific advantages: dry chemical agents have quick flame-knockdown and suppression properties; twin agent systems also provide quick knockdown (from the dry chemical component) as well as cooling (from the liquid agent) to reduce surface temperatures of heated metal below the flash combustion point. Stand-alone liquid-agent systems offer simplified design/configuration and efficient performance in the proper application. Stromberg said that TFPP had noticed a gradual trend toward selection of its Ansul LVS single-agent systems by its mining customers, but the specific application will dictate which type of system should be used; for example, dry chemical agents can be effective when 'broadcast' into the general area in which a fire is occurring, while stand-alone liquid agents work best when sprayed directly on burning surfaces. TFPP's current top-of-the-line fire suppression product for mine vehicles is Reduce Hydraulic-system Fire Risks with Proper Maintenance and Repair Strategies Selection: • Ensure hydraulic components are 'like for like' and considered suitable for use. Always consult manufacturer before making changes. • Ensure any contractor installations/design modifications that are undertaken off-site are verified on-site by the employer before use and are equivalent to manufacturer's standards and design. • Implement quality checks by manufacturer-authorized service providers periodically as a cross check for internal maintenance. • Evaluate potential alternative higher flash point manufacturer-approved hydraulic oils, which contain polyol ester based fluids, phosphate esters or water glycol and emulsions. Such fluids must be compatible with existing components such as seals/fittings. Installation: • Properly fit any attached or existing hoses with approved manufacturer components. • Maintain hydraulic equipment with the appropriate tools. • Use fire-resistant anti-static hoses whenever possible and consider high-temperature-tolerant hoses designed for oil operating temperatures >150°C. 46 E&MJ; • FEBRUARY 2013 • Install and evaluate insulation around hot components, or insulate hoses near hot components and upgrade to braided armored hoses. • Ensure wiring is protected against fire, and connections are appropriate for manufacturer's requirements and are suitably located. • Consider the location and rating of protective devices such as fuses, solenoids and non-return valves. Inspection and Maintenance: • Complete pre-start checks for locating and acting on oil leaks, sprays and stains. • Use thermal imaging equipment to detect hot spots and high temperature areas during maintenance programs. • Ensure high-current wiring is not in contact with hydraulic hoses. • Routinely wash, clean and check hoses for signs of rubbing, oily mist or leaks. • Perform periodic checks on hydraulic braking systems to ensure sound operation, including bearings, brake drums, rotor and calipers. • Routinely check electrical wiring, including insulation. • Routinely check solenoid connections for corrosion and replace/ check at set engine hours or per manufacturer recommendations. Consider protective devices for solenoids, such as fuses. www.e-mj.com