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The Kidde Technologies Inc. site in Wilson, NC is an all-encompassing facility that is AS9100 Certified for the design and manufacturing of fire detection and suppression systems for aircraft. The plant consists of 131,000 square feet, on twenty-two acres, and is wholly company-owned.
Kidde became the industry leader in aircraft protection systems and components in the early 1930s. Since that time, Kidde has grown to over 800 employees. Our growth is attributed to strong technical resources and product knowledge, complemented with effective management leadership.

In addition to the new aircraft programs listed earlier, for which Kidde is carrying out extensive development work, the following R&D activity is of critical importance to the future of aviation fire protection.

There is currently over 1500 ft. 2 of laboratory space at the Kidde facility, divided into four separate areas: an electronic test and development lab, an optics lab, a mechanical test and development lab, and an analytical measurement lab.

Specialized Equipment and Simulators
The Kidde group of companies has unique test facilities not found in most fire protection hardware companies. Some examples include:
  • Engine Nacelle Fire Test Simulator; used primarily to evaluate new extinguishing agents and suppression system designs under simulated, dynamic conditions
  • Dry Bay Fire Test Simulator; used primarily to evaluate new extinguishing agents’ dispersion characteristics
  • Three Cargo Simulators ranging in size from 600 cubic feet to 4000 cubic feet
  • Gun Fire Test Range; capable of evaluating gunfire damage characteristics and simulated engine turbine blade penetration characteristics.
  • Various large-scale environmental chambers.
Other Facilities
Our Kidde Fire Protection affiliates maintain significant R&D capabilities: The department is made up of scientists and engineers with disciplines in physics, chemistry, analytical modeling, mechanical and electronic design and digital techniques. This group provides advanced research into new technologies and applications and offers unique measurement and test equipment.
Kidde can fully support the concept of electronic data exchange with our customers. Kidde has direct modem link, and e-mail capabilities, which allows regular transmission of text/data files to our international affiliate companies, out-of-house support personnel, consultants, and approved subcontractors. This link can also be made direct to any customer.
Halon Replacement Activities
Kidde has formed a Halon Task Force to conduct research and evaluation efforts, and to represent our position in several international policy making organizations related to this subject. Kidde is active in the development and evaluation of numerous fire extinguishing alternatives to the environmentally harmful Halons.
General Discussion
Kidde fully appreciates the dilemma the aircraft industry must face in deciding to pursue a new replacement agent to Halon 1301 for new applications. Progress has been made in generating the required performance, environmental and operational data for some agents to be considered as replacements although it is possible that some candidates will require significantly more agent to meet the same level of protection offered by Halon 1301. Alternate agent aviation fire suppression systems are currently being designed and fielded in military applications, however, certification criteria for commercial aviation systems are still under development. Based on these facts, it is difficult to select one agent that could be used in place of Halon 1301.

Kidde has been diligently working using our unique test facilities, capabilities and specialized resources. Some of the activities that we are involved in and offer include:
  • Specialized expert scientists and engineers who are diligently working the problem. In addition to KA's scientists and engineers, the Kidde Plc R&D organization supports the alternate agent activities of KA and our industry.
  • Member of several international committees dedicated to including other Halons (CFCs). Some committees:
    • United Nations Environmental Protection (UNEP) Group
    • Halon Alternative Research Corporation (HARC)
    • Halon Recycling Corporation (HRC)
    • International Halon Replacement Working Group (IHRWG). This group is perhaps the most important committee for Halon replacement in the aviation industry. Sponsored by the FAA, the IHRWG is currently developing minimum performance standards and certification criteria for Halon replacements for engine nacelles, Advanced Pneumatic Detectors (APUs), cargo bays, portable extinguishers and lavatory extinguishers.
    • The Advanced Agent Working Group
A number of internally funded activities have been undertaken.
  • Small scale cup burner testing to assess the relative performances of various agents.
  • Material compatibility testing.
  • Medium scale simulator, inerting and explosion testing.
  • Large scale demonstration testing at the FAA technicalcenter, Wright Patterson Air Force Base (WPAFB) and the Army's Aberdeen Proving Ground (APG).
  • Following the efforts of other organizations and companies who are assessing toxicity, long term stability, environmental characteristics, etc.
The availability of several unique test simulators and facilities. They include:
  • A dynamic engine nacelle test fixture, which is capable of evaluating the pan fire extinguishing efficiency of various extinguishing agents: A dry bay test facility which is used to study the three dimensional fast fire/explosion suppression characteristics of various alternate agents under conditions of temperature extremes and high airflow
  • A cargo bay test rig which has a volume of 1000 cubic feet, used to assess the extinguishing and inerting characteristics of alternate agents
  • Gun fire test range with a .50 caliber gun
  • Fast response Halon (and other gases) concentration measurement equipment
  • On-line combustion gas analyzers (CO, CO 2 , O 2 )
  • The market introduction of the first environmentally friendly "Recovery and Conditioning of Halon" (REACH TM ) system. This system is the first to condition Halon to MIL-SPEC/ASTM standards and still only release less than 2-3% to the atmosphere during the re-cycling process.
Therefore, we firmly believe that with the level of effort and resources that we are currently committing to this activity, Kidde will be the first to introduce the replacement agent for Halon 1301 as they apply to aircraft. And in the interim, we will design and make provisions for continued use (in an environmentally efficient manner) of recycled Halon 1301, if that is our customer's preference.

Extinguishing Agent Trade Study Considerations
Table 1 provides a list of the currently available Halon replacement agents that are being considered for use in the aviation industry. These agents are similar to Halon 1301 in terms of the hardware and system architecture required to store and then apply the agent to the fire. Also shown in Table 1 are Halon 1301, 1211, 1202 and 1011 for reference. Most of the Halon replacement agents are included in Table 1. However, a few have been eliminated because of their high Ozone Depletion Potentials (ODP) (i.e. the hydrochlorofluorocarbons (HCFCs) whose production will be phased out in the near future) or long atmospheric lifetimes and global warming potentials (i.e. the perfluorocarbons (PFCs) which can only be used when no other agent is feasible). Other technologies, such as water mist and inert gas systems are available and could replace Halon 1301. These technologies would require different systems than currently used and are discussed at the end of this section.

Table 1 identifies the various nomenclatures associated with each agent as well as physical and chemical properties. An agent with an ODP > 0 is not acceptable for use. ODP is reported relative to the ODP of CFC-11 (which is assigned an ODP of 1). There is no formal international policy regarding GWP, but current sentiment is that if an agent has a significant GWP value, its use could be limited/affected/regulated in the future. To some extent this has already occurred with the limitation on use of PFCs. Thus low GWPs are highly desirable. GWP is reported relative to carbon dioxide (which has a GWP of 1).

With respect to atmospheric lifetime, this number identifies the stability of a particular chemical when released to the atmosphere. The longer its atmospheric life, the more damaging it could be with respect to global warming.

It should be noted that agents with low boiling points and high vapor pressures are commonly called "gaseous agents" and higher boiling, lower vapor pressure agents are commonly called "streaming agents". For total flooding systems, lower boiling/higher vapor pressure agents are preferred, but their use is not exclusive; higher boiling agents have been successfully employed in aviation applications.

Table 1 includes acute inhalation toxicity information. The LOAEL (the lowest concentration of agent causing an adverse effect), and the NOEAL, (the highest concentration of agent without showing an adverse effect) for the various agents. The acute inhalation toxicity is where 50% of rats are killed after a four-hour exposure to the agent. It should be noted that a 15-minute exposure requirement has been used for some agents.

The table also includes a standard test, which offers insight with respect to each agent’s extinguishing efficiency: the cup burner test. This test indicates the amount of agent in volume percent required to extinguish a heptane flame contained in a burner cup. Heptane fuel is the "standard" fuel for measuring extinguishing performance; however, methanol data is also shown. The relative performance, based on the heptane burner cup test, is also shown in the table. The volumetric concentration is converted, based on the agent's density and molecular weight, to the amount required on a mass basis, and then this value is normalized to the amount of Halon 1301 required to extinguish a flame.

Similarly, the amount of agent on a liquid volume basis is also presented. This gives one an idea how much bigger an alternate agent vessel would have to be to contain the agent.

The amount of agent required to inert a compartment is shown for reference. Typically this requires more agent to keep a flame from igniting than to extinguish a flame.

Lastly, the chemical companies that are supplying these agents are shown for reference. All the chemicals shown are commercially available.

Upon review, it is evident that there is no clear winner with respect to a replacement for Halon 1301 in fire suppression systems that will use similar hardware and architecture. Each candidate has at least one characteristic that makes it inferior to Halon 1301. Thus when considering these agents for future applications, the trade-off of the least important property to the customer will have to made.

Other technologies such as water mist and inert gas systems are also receiving the attention of the aviation fire protection community. These systems use radically different hardware and system architectures to Halon 1301 systems.
  • Conventional inert gas systems are large and heavy and therefore unattractive to the aviation community. However, some new and novel inert gas systems have been demonstrated to work on some military applications. Inert gases can be generated pyrotechnically (for dry bay suppression systems) or by on board inert gas generator systems (for fuel tank inerting systems). It should be noted that technical barriers do exist before these types of systems can find more widespread employment but the environment benefits will ensure that research will continue in this area.
  • Water mist and water mist inert gas systems have been demonstrated to work on the cargo fire threat. System weights are comparable with Halon 1301 if a zonal method of water mist application is employed. Water mist systems are more complex that those of Halon 1301 but, again, the environmental benefits will ensure research in this area
Both the technologies mentioned above are extremely promising but their use will probably be limited to cargo bays only and cannot be utilized without more detailed test work.
Table 1. Alternate Agent Properties 

Trade Study Recommendation
Based on the above factors, either CF3I, FE-25 TM or FM-200â are recommended for most aviation applications that want a "halon-like" based systems such as engine nacelle, APU and dry bay fire protection systems. FM200 is considered the best agent for cargo bay fire protection. The reasons for the recommendation are as follows:
  • Only CF3I, FM-200 Ò and FE-25 TM have acceptable
  • FE-25 TM has a desirable vapor pressure for Halon-like distribution at low temperatures, however, agents with similar volatilities to CF3I and FM-200 Ò have been used in low temperature applications before and these agent have been demonstrated to work at low temperatures.
  • For engine nacelle applications, CF3I, FE-25 TM and FM-200 Ò have been deemed acceptable for use in terms of their toxicological properties (these agents are all EPA approved for use in non-occupied spaces). FM-200 Ò may be the only agent considered for use in cargo applications, as it is EPA approved for use in occupied spaces.
  • With respect to extinguishing efficiency, CF3I is by far the most efficient but it can only be used in unoccupied spaces. FM-200 Ò is more efficient than FE-25 TM on a system weight.
  • CF3I, FM-200 Ò and FE-25 TM are currently available and approved by the EPA and NFPA for production use. Gas generator systems and water mist systems may not be used.
  • FE-25 TM has been fielded in production military engine nacelle and APU applications. FM-200 Ò has been employed in over 40,000 industrial fire protection systems worldwide.
  • There are still some concerns regarding exposure constraints, handling, and long term storage of CF3I.

Water mist and inert gas systems may be used in the future for cargo systems.

Through the IHRWG, the aerospace community is currently expending effort on identifying and designing alternate agent replacement systems. Once the certification criteria for these new agents are developed, Kidde will be ready to work with OEMs to design new environmentally friendly systems.
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