Gas-fueled, computer-controlled, systems: Delivering Safe, Live Fire Training


By Don T. Brady
Carolina Fire Rescue EMS Journal


Live fire training is a crucial element in the firefighting training curriculum. Yet, a number of factors are making it increasingly more difficult to provide this essential live fire training using the traditional methods. The use of acquired structures for live fire training has demonstrated incident after incident that these training methods can be unpredictable and difficult to control. Concern for personnel safety and liability is increasing as a result of firefighters being seriously injured and killed in training fires set in acquired structures. Live fire-training methods such as burning diesel fuel or Class A combustible materials in a conventional burn building are also being criticized because of the resulting air, water, and soil pollution. Many facilities that once used these methods have been closed down by government environmental agencies. The structural degradation of fire service burn buildings and the maintenance cost associated with the uncontrolled burning of combustible materials within burn buildings have caused still other facilities to close or undergo extensive and often costly repairs.

So what is a training officer to do?

Gas-fueled computer-control as a solution

A gas-fueled, computer-controlled live fire training system is a viable solution to these problems, and is a solution that many communities are adopting. Large cities like New York, Charleston, Dallas, Memphis, Toronto, and San Francisco, as well as smaller, more rural communities like Yakima, WA have adopted gas-fueled trainers to meet their training needs.

These gas-fueled, computer-controlled training systems realistically replicate fire emergencies; yet do so in a safe, controlled, and environmentally sound manner. At the center of the trainer is a fail-safe, closed-loop, and industrial-hardened computer-control system. The computer-control system creates the training fires, and continuously monitors and regulates the environment within the training space to keep it within acceptable limits. Fires are initiated and, more importantly, can be extinguished by the instructor at the touch of a button. In an emergency situation, the control system automatically extinguishes the fires and ventilates all heat and smoke from the burn room. The instructor can also do the same by hitting an emergency stop button.
The basic operation of a gas-fueled, computer controlled fire training system.

Training fires are fueled by either natural gas or propane; these clean-burning fuels do not produce the volatile organic compounds (VOC'S) and soot that conventional fuels generate. The systems also use simulated smoke that is actually an environmentally- benign, flame-safe aerosol fog. Because there are no products of combustion that become entrapped in the extinguishing water, runoff from these trainers can usually be safely discharged into conventional sewer systems. Gas-fueled, computer-controlled burn buildings across the U.S. successfully operate in suburban neighborhoods without adverse effects on neighbors.

A typical fire scenario
A typical fire scenario is initiated by an instructor with the push of a button. Copious, thick simulated smoke quickly fills the training space, replicating a smoldering fire. The word "simulated" may be a misnomer and may be misleading- the smoke is very real in its ability to quickly obscure vision to the point where one's hand cannot be seen at arm's length. The gas-fueled fires are certainly real as well. The radiant heat from the fires can quickly produce temperatures of 500 degrees Fahrenheit at the 5-foot level, and over 1,000 degrees Fahrenheit at the ceiling.

As a hoseline team attacks the fire, sensors within the training space detect the application of extinguishment agents. If properly applied, the computer-control system immediately modulates the flames to produce a realistic response. Proper agent application leads to extinguishment, while improper agent application can cause torching, flare-ups, or even a rollover. Although the most common extinguishment agent used in these training systems is water, systems are available that respond to a multitude of agents, including; CO2, dry chemical, AFFF and CAF. In addition to real extinguishing agents, these systems can also be configured to respond to surrogate agents. (A surrogate agent simulates the same physical appearance as the real agent, but is environmentally friendly.)

Enhanced Training
Unlike traditional methods, computer-controlled, live-fire training systems provide an almost infinite level of control and repeatability. Fire parameters like flame height, growth, spread, and extinguishment difficulty are just some of the parameters the operator can select and alter to challenge both new and seasoned firefighters. Fires can be set to automatically rekindle if proper overhaul and soaking is not performed. Optional flashover-rollover effects can be included to dramatically reinforce the importance of cooling ceiling gases. Advanced training systems can even provide student tracking, data logging, and scenario storage capabilities. Once configured, a fire scenario can be run over and over again by simply pressing a button. More time can be spent training, since there is no need for the messy set up and clean up of Class A or Class B materials before and after each burn scenario.

Reduced stress on a burn building
Although the heat produced by these gas-fueled training fires is typically as hot or hotter than the traditional training fire, the fire is controlled and the actual burn time is much shorter, which significantly reduces the thermal stress on the burn structure. Traditional Class A and Class B training fires cause significant thermal stress to the burn building because heat is absorbed into the building structure itself. Standard structural materials like concrete, masonry, and steel are damaged by the thermal shock, which results when structural members are heated and then are rapid cooled by quenching with firewater.

To slow down the heat absorption process, thermal lining systems are typically installed in burn rooms. Commonly used lining systems include steel plates, calcium silicate panels, refractory tiles, sacrificial masonry block, and spray-on refractory concrete. Regardless of the lining system installed, its ability to protect the structure is ultimately a function of the training fires themselves. Uncontrolled fires and long burn times can damage the lining system and compromise the lining system's ability to protect the structure. Computer-controlled fires do not subject a building to the same thermal stresses, because the fires are of relatively short duration and the environment within the burn room is monitored and controlled within acceptable limits. Unlike traditional burn rooms, which typically have all walls and ceiling surfaces lined, computer-controlled burn rooms are typically lined only in areas of possible direct flame impingement. This results in a significant cost savings in terms of initial purchase cost, as well as maintenance cost.

Numerous scenarios
The development of the first gas-fueled, computer-controlled live-fire training systems began in 1978, with the first system being installed at the U.S. Navy's Norfolk Naval base in 1984. Since that time, the technology has continued to evolve, and hundreds of training systems have been installed throughout the world. Fire-training organizations have used various versions to train for structural fires, aircraft rescue fire fighting (ARFF), shipboard fires, submarine fires, industrial fires, petrochemical plant fires, transportation fires, and HAZMAT emergencies.

Gas-fueled, computer-controlled systems also enable fire departments to create unique fires scenarios that are not easily replicated with conventional live fire methods:

* Hidden ceiling fires - The new burn building at the FDNY Fire Academy utilizes a "cockloft" ceiling fire. Hidden fires above false ceilings "cocklofts" can be particularly dangerous if not approached properly. Fire can extend overhead and entrap a firefighter deep within a structure.

* Attic fire - Fires have been configured in the attic of a gable-roofed burn building. This scenario is particularly difficult, due to the low ceiling and simulated floor joists.

* Electrical panel fires, Class C- Gas-fueled fires can easily be configured to smolder inside an electrical panel mockup. When the student opens the panel door, the fire flares up, fully engulfing the panel and the wall behind it. Students must secure power to the panel, or attack the fire with CO2 or powder surrogate. In the event a student applies water directly to an energized panel, a loud bell or sound indicating a potentially fatal mistake is emitted.

* Fire Extension- Fires can be configured to automatically extend from a first floor to an upper level of the structure, forcing students to anticipate fire extension possibilities.
An Attic Fire Gas-fuel fires allow the replication of a wide range of emergency scenarios.

Fire above "cockloft" or drop ceiling


Safety first- Guidance from NFPA

The design and installation of gas-fueled fire training systems requires engineering expertise and experience to ensure the safety and reliability of the overall operation. NFPA 1402, 2002 edition, Guide to building Fire Service Training Centers provides important guidelines for fire departments considering the purchase and use of these systems. The guide is available from the NFPA at www.nfpa.org. The following minimum requirements should be considered:

· All installations should comply with NFPA 54, National Fuel Gas Code, and NFPA 58, Liquid Petroleum Gas Code.

· All components of the system should be certified and labeled by a nationally-recognized (third party) testing laboratory (NRTL) to ensure compliance with the requirements of UL 508, Standard for Industrial Control Equipment and NFPA 86, Standard for Ovens and Furnaces.

· Pilot flames should be interlocked with fuel delivery valves to prevent fuel from flowing without confirmed pilot flames being present. Pilot Flames should be monitored at the point they ignite the main burner element. Upon loss of pilot flame, all gas valves should automatically close.
An electrical panel fire

· All burner controls should include at least two gas valves in series that close automatically in response to a loss of electrical power.

· Combustible gas detection should be provided in all training and equipment spaces. These detection systems should be interlocked with the system ventilation system and fuel delivery valves to shut down the flow of fuel and activate and external alarm when the level exceeds 25 percent of the lower explosive level (LEL). Ventilation system design should consider the potential accumulation of unburned gases above, below, or adjacent to the fire area.

· Adequate air should be provided to ensure complete combustion of the gas. Depending on the facility's configuration, mechanically assisted ventilation might be necessary. Where mechanical ventilation is provided, airflow switches, buttons, and wiring should be approved for the temperature environment.

· Emergency stop buttons or valves should be placed adjacent to each burn room to provide immediate shutdown in the event of an accident.

· A ventilation system capable of removing heat, smoke, and unburned gas should be installed in the building. The ventilation system should be interlocked with the emergency stop switches, temperature sensors, and gas monitors. The ventilation system should be sized to provide a minimum of one air change per minute in the training space, and a manual override should be provided in the event that the interlocking device fails.

Design and Installation
Whether retrofitting an exiting burn building, or planning a new facility or burn prop, fire departments considering the purchase of a gas-fueled, computer-controlled live-fire training system should first establish their training objectives. Once the training objectives are established, fire departments should meet with a training system supplier. The supplier should be a professional firm with experience in the design and installation of gas-fueled, computer-controlled live-fire training systems. The training system supplier should also be experienced in the development of live-fire training centers, burn buildings, and burn props.

For the typical fire department training officer, the process of developing live-fire training center or burn building is a once-in-a-career opportunity. Working with a professional training system supplier that has experience with similar or more complex projects can make the process easier. Much like drawing on the experience of other training academies, experienced fire-training system suppliers have the knowledge needed to incorporate training features and to avoid unforeseen mistakes. They can identify design and construction options. They can advise on ways to make the training building more user-friendly and durable. They can identify training system features, and recommend configurations that meet the training objective. Experienced suppliers can identify utility requirements, fuel choices, and required gas-flow rates. Professional firms experienced with gas-fueled, computer-controlled training systems routinely work with clients throughout the conceptual design process and provide
preliminary burn building and facility layout information.


Conclusions
Gas-fueled computer-controlled live-fire training systems offer numerous advantages over conventional means of training, including safety and environmental compliance. Training organizations or fire departments interested in learning more about these trainers are encouraged to speak with other organizations that have already "gone with gas." Further, knowledgeable sources for information are gas-fueled training system suppliers, architects, and engineers who have worked with these systems in the past.

Don T. Brady is a Senior Project Engineer for Kidde Fire Trainers based in Fair Lawn, New Jersey. Mr. Brady is a voting member of the NFPA Technical Committee on Fire Service Training. He has 15 years of experience in burn building design, holds 2 patents for gas-fueled fire training systems, and has worked on over 75 burn building projects throughout the U.S., Europe and Asia.

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