Innovative, single-agent fire safety solutions can simplify installation, activation and clean up when protecting heavy-duty industrial mobile equipment from fire risk. 

By Kristin Ryczek

Since the 1950s, fire suppression solutions have become more sophisticated to match the ever-growing complexity of ultra- and mega-class mining vehicles. Capable of moving hundreds of tons of material, these industrial vehicles have bigger parts, contain larger engines, carry larger quantities of fuel and, consequently, present a higher fire risk than standard industrial vehicles. 

While dry chemical systems have been the go-to for fire protection on large, industrial vehicles since the 1950s, dual-agent systems emerged in the 1990s to better protect ultra- and mega-class giants. Despite the availability of an FM-approved, single-agent system, National Fire Protection Association (NFPA) standards require the use of a twin-agent suppression system in ultra- and mega-class equipment with “hydraulic systems containing more than 150 gallons in the lines.” 

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 minimizes 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, in addition to shifting regulations regarding the use of per- and polyfluoroalkyl substances (PFAs), emphasize the need for a new, non-fluorinated fire suppression solution that simplifies fire protection while meeting the needs of today’s heavy-duty industrial vehicle operations.

Testing an innovative new solution 
The latest evolution of firefighting technology has the potential to provide extraordinary performance for ultra- and mega-class earthmovers, exceed the capabilities of previous systems and simplify fire suppression system design. 

The ANSUL Vehicle Systems fire team recently conducted extensive testing to evaluate the effectiveness of a new, non-fluorinated single-agent liquid system versus some of the leading single-agent and twin-agent setups currently used in the industry.

According to the Queensland Mines Inspectorate, 60% of fires on turbocharged diesel engines resulted from hydraulic or engine oil spraying on the turbocharger, 11% were caused by engine fuel contacting the turbocharger and 13% from turbocharger failure. With these statistics in mind, the chosen fire test protocol required agents to achieve the following:

  • Suppress fire through a pressurized fuel spray.1 
  • Cool a superheated surface (simulating a turbocharger, manifold, etc.).
  • Extinguish a fuel pool fire that could potentially be caused by fire/fuel propagation in real-world scenarios.
  • Prevent flame reflash.

Tackling any one of these four objectives is difficult, but the protocol used incorporates all of them into a single test. What makes this test especially challenging is that the suppression agent is sprayed horizontally at the vertical reignition plate and must, therefore, suppress and secure the pool fire by indirect coverage. 

Here are the test results:

Achieving meaningful results 
The testing demonstrates the speed at which the new ANSUL LVS NF-40 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. What’s more, the lower discharge time illustrates that less ANSUL LVS NF-40 agent is required compared to the legacy LVS agent for effective fire suppression.

Given that the dry chemical used in test #1 could not knock down the flames alone, tests #3 and #4 suggest that the addition of a liquid agent – either legacy or NF-40 – suppressed and secured the pool fire. 

Tests #3 and #4 also demonstrate another shortcoming of the dry chemical. Although the twin-agent systems achieved complete suppression, the thermocouple data showed that the plate remained superheated. It is thought that the dry chemical created a barrier that isolated the heat of the plate from the fuel spray and prevented the LVS liquid agent from efficiently removing the heat from the plate surface. 

Consequently, these tests demonstrate that the dry chemical component of a twin-agent system is not only ineffective in suppressing the fire, but it may even hinder the suppression effect of the liquid agent. In other words, under these testing conditions, it was more effective to use ANSUL LVS NF-40 as a stand-alone system. This finding should influence the future design of heavy vehicle fire suppression systems. 

The physiochemical properties of ANSUL LVS NF-40 also impact fire suppression system design for haul trucks and other mining vehicles. 

The enhanced properties of this new agent allow for installation of more nozzles per tank and make it possible for each nozzle to cover more area compared to previous liquid agents. This design flexibility is critical as the size and complexity of these vehicles continues to grow. 

With NF-40 liquid agent, the number of nozzles per tank may range from one to 24, depending on the size of the tank. The nozzle design and an extended maximum spray distance of 54 inches helps the agent flow into hard-to-reach areas along the same path where flammable liquids may have migrated. An operating temperature range of -40 °F to 140 °F (-40 °C to 60 °C) helps ANSUL LVS NF-40 agent protect mining operations in the most extreme conditions. 

Advancing vehicle fire suppression systems
While heavy industrial vehicles have depended on twin-agent fire protection systems for decades, and some applications still require them to meet the NFPA 120 and 122 standards, twin-agent systems are complex to install, activate and clean up. Use of the ANSUL LVS NF-40 suppression agent alone not only streamlines these complexities but can also provide a higher performing and more cost-effective fire protection solution for ultra- and mega-class mobile equipment. 

This advancement in fire protection technology offers the mining industry a new stand-alone, single-agent option while meeting the growing need for a high-performing non-fluorinated solution. 

Utilizing new insights gained from the in-depth testing conducted at the Johnson Controls Fire Technology Center of Excellence, mining operations can select the most effective vehicle systems solution for protecting personnel, property and operational continuity. 

Full testing details, specifics about the agent and more about this work (including a video) can be viewed at our web site.

About the author: Kristin Ryczek is Global Product Manager, ANSUL Vehicle Fire Suppression Systems, Fire Protection Products, at Johnson Controls.

1 Standard hydraulic fluid was utilized for this test. There are heat-resistant hydraulic fluids with autoignition temperatures above that of diesel fuel, but to make the test more universal and more stringent, these heat-resistant fuels were not used.

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