10/XX/10 AC 20-42D Appendix 2
12. Halocarbon Agent is comprised primarily of one or more organic compounds containing one or more of the elements fluorine, chlorine, bromine, or iodine. Halocarbon agents are electrically non-conducting, volatile liquids, or gaseous fire extinguishants. As "clean agents", they do not leave a residue on evaporation. Halocarbon agents (halons and halon replacements) that are currently commercialized include the hydrochlorofluorocarbons (HCFCS), perfluorocarbons (FCs or PFCs), hydrofluorocarbons (HFCs), fluoroiodocarbons (FICs), and fluoroketones (FKs), as well as the completely halogenated halocarbons (halons). Halocarbon agents are multipurpose class A, B, Crated agents and are most effective on Class B and C fires.
Advantages of halocarbon agents include low cold shock characteristics on electronic equipment, no degradation of visual acuity, and low pressure.
13. Halocarbon Blend is a mixture of 2 or more halocarbon agents in a portable extinguisher.
14. Halon is a short derivation for "halogenated hydrocarbon." The chemical structure is identified as a four digit number representing, respectively, the number of carbon, fluorine, chlorine, and bromine atoms present in one molecule. Both Halon 1211 and Halon 1301 are liquefied gases and typified as "clean agents." Halons primarily extinguish fire by chemically interrupting the combustion chain reaction rather than by heat removal or physically smothering.
15. Halon Equivalent Extinguisher is an extinguisher containing a clean agent which meets the MPS for hand-held fire extinguishers (see appendix 3 reference paragraph 7s of this AC).
Equivalency does not refer to agent weight, but the effectiveness of extinguishing a fire. Halon replacement extinguishers may be more than twice the weight of halon extinguishers.
16. Halon 1211 has the chemical name bromochlorodifluoromethane, CBrC1F2. Halon 1211 is a multipurpose, Class A, B, C rated agent effective against flammable liquid fires. Due to its relatively high boiling point of +26°F (-4°C). Halon 1211 discharges as an 85 percent liquid stream offering a long agent throw range.
17. Halon 1301 has the chemical name bromotrifluoromethane, CBrF3. Halon 1301 is recognized as a multipurpose agent having Class A, B, C capability in total flooding systems.
However, Halon 1301 offers limited Class A capability when used in portable fire extinguishers.
The boiling point for this agent is -72°F (-57.8°C). Halon 1301 discharges as a gas.
18. Halon Replacement Agents are any clean agents which can be either a non-halon (halocarbon agent) or halon alternative (all other substitute agents) that have SNAP approval by the U.S. EPA and meet the MPS for hand fire extinguishers.
19. Hand Fire Extinguisher is an approved, aircraft portable fire extinguisher which can be used by aircraft occupants to combat accessible, incipient, on-board fires.
21. HFC-227ea is an extinguishing agent that is comprised of the chemical 1,1,1,2,3,3,3- heptatluoropropane (CF CHFCF3). The boiling point of the agent is 2.5°F (-16.4°C). Due to this boiling point, HFC-227ea is discharged as a mixed liquid and vapor stream which readily evaporates. It is a multipurpose agent with class A, B and C capability.
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Appendix 2
22. HFC-236fa is an extinguishing agent that is comprised of the chemical 1,1,1,3,3,3 hexafluoropropane (CF3CH,CF3). The boiling point of the agent is +29.5°F (-1.4°C). Due to its relatively high boiling point, HFC-236fa discharges predominately as a liquid stream which readily evaporates. It is a multipurpose agent with class A, B and C capability.
23. HCFC Blend B is an extinguishing agent that is a tertiary blend comprised primarily of the chemical 2,2-dichloro-1,1,1-trifluoroethane HCFC-123, (CFCHCI). Two inert gases are blended with the HCFC-123 to enhance flow distribution and fire extinguishing performance.
The boiling point of the blend is 80.6°F (27°C). Due to its high boiling point, HCFC Blend B discharges primarily as a liquid stream which readily evaporates. It is a multipurpose agent with class A, B, and C capability.
24. Labeled equipment or materials have an attached label, symbol, or other identifying mark of an organization that is acceptable to the authority having jurisdiction and concerned with product evaluation that maintains periodic inspection of production of labeled equipment or materials, and by whose labeling the manufacturer indicates compliance with appropriate standards or performance in a specified manner.
25. Listed refers to equipment, materials or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services. The organization maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and who's listing states that the equipment, material or service meets appropriate designated standards or has been tested and found suitable for a specified purpose.
26. Listing Mark is a certification mark allowed to be carried as a stamp of approval by nationally recognized standards/testing organization.
27. Lithium Ion Battery is a rechargeable battery that has an anode made from a metal oxide composite containing lithium ion, and a cathode made from a specialized carbon material.
Charge and discharge of the battery is facilitated by the movement of lithium ions in electrolytic solutions. Lithium ion batteries are used in small electronic devices such as pagers, portable computers, camcorders, and portable telephones.
28. Lithium Primary Battery is a rechargeable battery that has a lithium anode and a cathode system consisting of carbon and either thionyl chloride or sulfuryl chloride.
29. Lowest Observable Adverse Effect Level (LOAEL) is the lowest concentration at which an adverse physiological or toxicological effect has been observed in dogs.
30. Maximum Certificated Occupant Capacity is the maximum number of persons that can be carried for each specific aircraft model as certified by the authority having jurisdiction.
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Appendix 2
31. Minimum Performance Standard (MPS) for Hand Extinguishers refers specifically to two tests that hand extinguishers containing halon replacement agents must pass. See appendix 3 reference paragraph 7s. These fire tests demonstrate equivalent fire extinguishing performance currently used in aircraft and assess the toxicity of the decomposition products.
32. Minimum Safe Volume refers to the smallest compartment volume into which one extinguisher could be discharged, assuming perfect mixing of agent, without posing a toxicity hazard. Minimum safe volumes are dependent on the agent, the agent weight, ventilation, and pressure altitude of the discharge.
33. Neat in this context refers to un-decomposed agent.
34. No Observable Adverse Effect Level (NOAEL) is the highest concentration at which no adverse physiological or toxicological effect has been observed in dogs.
35. Physiologically Based Pharmacokinetic (PBPK) Model is a mathematical model for human health risk assessment and investigation of toxicity. The health concern for halocarbons, including halons, is cardiac sensitization which occurs at a fixed target arterial concentration.
The model estimates the allowable arterial blood concentration as a function of agent exposure time to establish both the concentration of agent and duration to which personnel could be safely exposed. The PPK modeling is endorsed by the U.S. EPA and the NFPA.
36. Rated/Rating is a numerical value assigned to an extinguisher based on its fire extinguishing capability.
37. Safe Human Exposure Concentrations are based on PPK modeling. Safe human concentrations are exceeded when the simulated arterial concentration exceeds the target arterial concentration.
38. Small Aircraft are defined by part 23.
39. SNAP Program is EPA's significant new alternatives policy (SNAP) program to evaluate and regulate substitutes for ozone depleting chemicals that are being phased out under the stratospheric ozone protection provisions of the Clean Air Act.
40. Time of Useful Consciousness is the time available to don an oxygen mask without assistance.
41. Unventilated Compartment for the purposes of the AC is a compartment where the air change time is not known or exceeds 6 minutes.
42. Ventilated Compartment is a compartment where the air change time is known and does not exceed 6 minutes.
43. Volume Percent (% v/v) is the gas volume in liters per 100 liters of the resulting gas mixture, e.g. 2% v/v Halon 1211 mixture contains 2 liters Halon 1211 per 100 liters volume.
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Appendix 3 Appendix 3. Related Publications and How to Get Them Code of Federal Regulations (CFR). You can get copies of Title 14, 40, 46, and 49 of the Code of Federal Regulations, parts from the Superintendent of Documents, Government Printing Office, P.O. Box 37154, Pittsburgh, PA 15250-7954. Telephone (202) 512-1800; fax (202) 512- 2250. You can order copies Title 14 through the FAA website at http://rgl.faa.gov/. Select "Access" then "Online Bookstore." Select "Aviation," then "Code of Federal Regulations."
You can also get copies of 14 CFR sections on-line at www.gpoaccess.gov/cfr/ and copies of 40 CFR sections on-line at www.epa.gov/epahome/cfr40.htm. The following is a list of applicable Federal Regulations used for this AC:
14 CFR §§ 21.305, 23.561, 23.851, 23.1441, 23.1443-1449, 25.561, 25.851, 25.857,
25.1439, 27.561, 27.861, 29.561, 29.851, 29.853(e) and (t), 91.122, 91.211, 91.193, 121.309(c),
125.119(b) and (c), 127.107(c), 135.155.
b. Title 40 of the Code of Federal Regulations (40 CFR), Chapter I--Environmental Protection Agency, part 82-Protection of Stratospheric Ozone, subpart G-Significant New Alternatives Policy Program and subpart H-Halon Emissions Reduction (40 CFR part 82).
Title 46 of the Code of Federal Regulations (46 CFR), Chapter I-Coast Guard, Department of Transportation, part 34-Fire Fighting Equipment.
d. Title 49 of the Code of Federal Regulations (49 CFR), Transportation.
2. FAA Airworthiness Directive (AD). You can get copies of the following AD from the FAA's website at www.airweb.faa.gov/rgl.
a. AD 93-07-15, Boeing And McDonnell Douglas Models 707, 727, 737,747, and 757 and McDonnell Douglas Models DC-8, DC-9, and DC-10 Series Airplanes
3. FAA Advisory Circulars (AC). Order copies of Advisory Circulars (AC) from the U.S.
Department of Transportation, Subsequent Distribution Office, M-30, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20795. Telephone (301) 322-5377, fax (301) 386- 5394. To be placed on FAA's mailing list for free ACs contact, U.S. Department of Transportation, Distribution Requirements, Section, M-494.1, Washington, D.C, 20590.
You can also get copies at www.airweb.faa.gov/rgl. On the website, select "Advisory Circulars," then select "By Number."
a. AC 120-80, In-Flight Fires
b. AC 20-42C, Hand Fire Extinguishers for Use in Aircraft
c. AC 25-17, Transport Airplane Cabin Interiors Crashworthiness Handbook
d. AC 25-18, Transport Category Airplanes Modified for Cargo Service A3-1
Appendix 3
e. AC 25-22, Certification of Transport Airplane Mechanical Systems
f. AC 25-869-1, Fire Protection Systems
g. AC 65-9A, [Large AC] Airframe and Powerplant Mechanics General Handbook
h. AC 65-12A, [Large AC] Airframe and Powerplant Mechanics Powerplant Handbook
4. FAA Technical Standard Order (TSO). You can find the following technical standard orders on the FAA website at http://rgl.faa.gov/ or at www.airweb.faa.gov/rgl. You will also find the TSO Index of Articles at the same site.
a. TSO-C19, Portable Water-Solution Type Fire Extinguisher
b. TSO-C116, Crewmember Portable Protective Breathing Equipment
5. FAA Safety Alerts for Operators (SAFOS) and Information for Operators (InFOs)
a. SAFO 09013 Fighting Fires Caused by Lithium Type Batteries in Portable Electronic Devices, June 23, 2009, www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all safos/media/ 2009/SAFO09013.pdf
b. InFO 09010 Availability of a Federal Aviation Administration (FAA) In-flight Firefighting Training Video, June 23, 2009, www.faa.gov/other visit/aviation_industry/airline_operators/airline_safety/info/all infos/media/ 2009/info09010.pdf
6. FAA Training Videos:
a. "Extinguishing In-flight Laptop Computer Fires" and "Cabin Crew Firefighting Training Video," a training video on the use of hand extinguishers to fight on-board fires are available for viewing at www.fire.tc.faa.gov/2007Conference/session details.asp?sessionlD=26 Reports and Papers. Order copies of the following reports and papers from the National Technical Information Service, Springfield, Va. 22161. FAA publications can also be found on the following Web Site of the FAA Fire Safety Branch:
http://www.fire.tc.faa.gov/reports/reports.asp. Journal articles can be obtained directly from the publisher. Printed copies of Civil Aviation Authority documents are available from Documedia Solutions Ltd., 37 Windsor Street, Cheltenham, Glos., GL522DG, United Kingdom.
a. Abramowitz, A., Neese, W., Slusher, G, Smoke and Extinguisher Agent Dissipation in a Small Pressurized Fuselage, Federal Aviation Administration, Report No. DOT/FAA/CT- 89/31, 1990.
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Appendix 3
b. Blake, D.R., Effectiveness of Flight Attendants Attempting to Extinguish Fires in an Accessible Cargo Compartment, Federal Aviation Administration Technical Note DOT/FAA/AR-TN99/29, 1999.
Chattaway,A., The Development of A Hidden Fire Test for Aircraft Hand Extinguisher Applications, Civil Aviation Authority Paper No. 95013, London, 1995.
d. Cherry, R.G. W. et al, A benefit Analysis for Enhanced Protection from Fires in Hidden Areas on Transport Aircraft, Federal Aviation Administration Report No.
DOT/FAA/AR-02/50, CAA Paper 2002/01.
e. Colton, B., Gargas, M., Sweeney, L.,Setting Acute Exposure Limits for the Halotron 1 Clean Agent Onboard Aircraft Using Physiologically Based Pharmacokinetic Modeling, Submitted to Louise Speitel, Federal Aviation Administration, July 16, 2008.
1. Eklund. Thor I., Analysis of Dissipation of Gaseous Extinguishing Agents in Ventilated Compartments, Federal Aviation Administration Report No. DOT/FAA/CT-83/1, 1993.
Hill, R.G., and Speitel, L., In-Flight Aircraft Seat Fire Extinguishing Tests (Cabin Hazard Measurement, Federal Aviation Administration Report No. DOT/FAA/CT-82/111, December 1982.
h. Krasner, L.M., Study of Hand-held Fire Extinguishers aboard Civil Aviation Aircraft, Factory Mutual Research Corporation, Federal Aviation Administration Report No.
DOT/FAA/CT-82/42, 1982.
Lain, M.J.,Teagle, D.A., Cullen, J., Dass, V., Dealing with In-Flight Lithium Battery Fires in Portable Electronic Devices, Civil Aviation Authority Paper No. 2003/4, London, 2003, ©Civil Aviation Authority 2003.
Slusher, G.R., Wright, J.A., and Speitel, L.C., Halon Extinguishment of Small Aircraft Instrument Panel Fires, DOT/FAA/CT-86/26, December 1986.
k. Slusher, Gerald R., Wright, Joseph, Demaree, James, Halon Extinguisher Agent Behavior in a Ventilated Small Aircraft, Federal Aviation Administration Report No.
DOT/FAA/CT-86/5, 1986.
1. Slusher, G.R., Wright, J., Demaree, J.E., Neese, W.E., Extinguisher Agent Behavior in a Vantilated Small Aircraft, Federal Aviation Administration Report No. DOT/FAA/CT- 83/30, 1984.
m. Speitel, Louise C., Lyon, Richard E., Guidelines for Safe Use of Gaseous Halocarbon Extinguishing Agents in Aircraft, Federal Aviation Administration: Report No. DOT/FAA/AR- 08/3.
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Appendix 3
n. Tabscott, R.E. and Speitel, L.C. eds., "Options to the Use of Halons for Aircraft Fire Protection Systems- 2002 Update", Federal Aviation Administration Report No. DOT/FAA/AR- 99/63, Task Group on Halon Options, International Halon Replacement Working Group, U.S.
Department of Transportation, FAA William J. Hughes Technical Center, February, 2002.
O. Vinegar, A., Jepson, G.W. and Overton, J.H (1998), PPK Modeling of Short-term (0-5 min) Human Inhalation Exposures to Halogenated Hydrocarbons, Inhalation Toxicology, 10:411-429.
Vinegar, A., Jepson, G.W., Cisneros, M., Rubenstein, R. and Brock, W.J. (2000), Setting Safe Acute Exposure Limits for Halon Replacement Chemicals Using Physiologically Based Pharmacokinetic Modeling, Inhalation Toxicology, 12:751-763.
Vinegar, A (2001), Modeling Cardiac Sensitization Potential of Humans Exposed to Halon 1301 or Halon 1211 Aboard Aircraft, Aviation, Space and Environmental Medicine, Vol.
72, No. 10.
Vinegar, A., Jepson, G.W., Hammann, S.J., Harper, G., Dierdorf, D.S. and Overton, J.H.(1999), Simulated Blood Levels of CF3l in Personnel Exposed During Its Release from an F-15 Jet Engine Nacelle and During Intentional Inhalation, AIHA Journal, 60:403-408.
S. Webster, Harry, Development of a Minimum Performance Standard (MPS) for Hand- Held Fire Extinguishers as a replacement for Halon 1211 on Civilian Transport Category Aircraft, Federal Aviation Administration Report No. DOT/FAA/AR-01/37, 2002.
Webster, Harry, Flammability Assessment of Bulk-Packed, Nonchargeable, Lithium Primary Batteries in Transport Category Aircrafi, Federal Aviation Administration Report No.
DOT/FAA/AR-04/26, 2004.
Webster, Harry, Flammability Assessment of Bulk-Packed, Rechargeable, Lithium- Ion Cells in Transport Category Aircraft, Federal Aviation Administration Report No.
DOT/FAA/AR-06/38, 2006.
8. American Society of Testing and Materials (ASTM) Standards. You can get copies of the tollowing ASIM standards from ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Telephone (610) 832-9585. You can also order on-line at www.astm.org, or contact ASTM Customer Service at service@astm.org.
a. ASTM D7673-10, Standard Specification for Halon 1211.
Bromochlorodifluoromethane (CF2CIBr)
b. ASTM D5632-08, Standard Specification for Halon 1301, Bromotrifluoromethane
c. ASTM D5631-08, Standard Practice for Handling, Transportation and Storage of Halon 1301, Bromotrifluoromethane (CF 3Br) A3-4
Appendix 3
d. ASTM D 7122-05, Standard Specification for HCFC Blend B (CFCCIH, Ar, and CFa
e. ASTM D 7123-04, Standard Practice for Handling, Transportation, and Storage of HCFC Blend B (CFCCIH, Ar, and CF4)
f. ASTM 6064-03, Standard Specification for HFC-227ea 1,1,1,2,3,3,3- Heptafluoropropane (CFSCHFCFs)
g. ASTM D6065-05, Standard Practice for Handling, Transportation, and Storage of HFC-227ea 1,1,1,2,3,3,3-Heptafluoropropane (CFCHFCFs)
h. ASTM D6541-05, Standard Specification for HFC-236fa. 1,1,1,3,3,3- Hexafluoropropane (CFCH CF 3)
i. ASTM D6427-04, Standard Practice for Handling, Transportation, and Storage of HFC-236fa, 1,1,1,3,3,3-Hexafluoropropane (CF3CH,CF3)
9. Factory Mutual Research Corp. (FM). Order copies of the FM approval standards from FM Corporate Headquarters 1151 Boston-Providence Turnpike, P.O. Box 9102, Norwood, MA 02062 USA. Telephone +1-781-762-4300. You can also order on-line at www.fimglobal.com:
10. International Organization for Standardization (ISO). Order copies of the following ISO standards from ISO, 1, rue de Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland.
Telephone +41-22-749-01-11. You can also order on-line at www.iso.org:
a. ISO 7201-1:1989, Fire Protection -- Fire Extinguishing Media - Halogenated Hydrocarbons -- Part 1: Specifications for Halon 1211 and Halon 1301.
11. National Fire Protection Association (NFPA). Order copies of the following NFPA standards from NFPA, 1 Batterymarch Park, Quincy, MA 02169-7471. Telephone +1 800 344- 3555 or +1 617 770-3000. You can also order on-line at www.nfpa.org:
a. NFPA 10, Standard for Portable Fire Extinguishers, 2007 Edition
b. NFPA 12A, Standard on Halon 1301 Fire Extinguishing Systems, 2009 Edition
c. NEPA 12B, Standard on Halon 1211 Fire Extinguishing Systems, 1990 Edition (No longer an active standard)
d. NEPA 2001, Standard on Clean Agent Fire Extinguishing Systems, 2008 Edition A3-5
Appendix 3
12. RTCA Inc. Documents. Order copies of the following RTCA Inc. documents from RTCA Inc., 1828 L Street NW., Suite 805, Washington, D.C. 20036. Telephone (202) 833-9339, fax
(202) 833-9434. You can also order copies online at www.rtca.org.
a. RTCA/DO-160F, Environmental Conditions and Test Procedures for Airborne Equipment
13. SAE Documents. Order copies of SAE Aerospace Standards from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001. Telephone (724) 776-4970, fax (724) 776-0790. You can also order copies online at www.sac.org.
14. Underwriters Laboratories, Ine (UL). You can get copies of the following U.S. - UL standards from UL Corporate Headquarters, 333 Pfingsten Road, Northbrook, IL 60062-2096 USA. Telephone Customer Service +1-877-ULHELPS (1-877-854-3577). You can also order
a. U.S. - UL 154, Carbon-Dioxide Fire Extinguishers (Ninth Edition), April20, 2009.
b. U.S. - UL 299, Dry Chemical Fire Extinguishers (Tenth Edition), April 20, 2009.
c. U.S. - UL 626, Water Fire Extinguishers (Eighth Edition), January 31, 2007.
d. U.S. - UL 711, Rating and Fire Testing of Fire Extinguishers (Seventh Edition), April 13, 2009.
e. U.S. - UL 1093, Standard for Halogenated Agent Fire Extinguishers (Fifth Edition), November 30, 1995. (UL intends to withdraw this standard effective October 2014)
1. U.S. - UL 2129, Halocarbon Clean Agent Fire Extinguishers (Second Edition), January 31, 2007.
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Appendix 4 Appendix 4. Explanatory Material
1. Effective Throw Ranges. Typical throw ranges for halocarbon and water extinguishers are listed in Figure 4 below.
Figure 4. Effective Throw Ranges for Halocarbon Halon Replacement and Water Extinguishers Effective Throw Ranges for UL/ULC Agent Rated Extinguishers*,° (ft.)
2-B:C 5-B:C 1A-10B:C 2A-10B:C 2A-40B:C HCFC Blend B 6-10 9-15 9-15 N/A 12-18 N/A HFC-236fa 8-10 10-12 14-16 N/A 14-16 N/A HFC-227ea N/A 8-10 N/A N/A N/A N/A Halon 1211 9-12 9-15 12-18 N/A N/A 12-18 Halon 1301 N/A N/A N/A N/A N/A NIA Water© N/A N/A N/A 45-55 N/A N/A a Throw range is extinguisher dependant and may differ from tabulated values.
b Check the manufacturer's literature for the throw ranges of their extinguishers.
c Initial Throw Range
2. Safe-Use Guidance. The toxicity guidance for the inhalation of halocarbon vapors is conservative. The development of this guidance can be found in the report referenced in appendix 3, paragraph 7m of this AC. The methodology used applies pharmacokinetic (PBPK) modeling of canine blood concentration data to perfect mixing agent decay curves. A particular PBPK model and target arterial concentration was used, as outlined in Section 4.1.2 of the aforementioned report. It assumes a compartment temperature of 70° F (21°C) at the stated pressure altitude, perfect mixing of the agent, and an agent weight of the largest extinguisher in that aircraft compartment. As a result, Halon 1211 safe-use concentrations are lower than in the previous AC. The guidance allows for adjustments for ventilation, localization and agent stratification, resulting in higher safe-use concentrations. You may elect to use safe-use W/V guidance or the minimum safe volume guidance. Both are outlined below. If used, this generally conservative guidance should protect passengers and crewmembers from neat agent toxicity, i.e. both cardiotoxicity and anesthetic effects.
a. Agent Safe-Use W/V Guidance. Consider the following:
(1) The total agent charge weight of the largest required extinguishers in a compartment divided by the compartment volume should not exceed the safe-use W/V.
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Appendix 4
(2) Multiplication factors, MF Ventilated may be applied to the safe-use W/Vs found in Figure 5 below resulting in higher safe-use agent concentrations in ventilated compartments where the air change time is known. See Figure 6 below or reference report appendix 3, paragraph 7m of this AC for the multiplication factors. These multiplication factors, referred to as the ventilation benefit in the reference report, are based on perfect mixing.
Figure 5. Safe-Use Agent W/V for Halocarbon Extinguishers in Unventilated Passenger and Crew Compartments Maximum Safe W/V (Ibs/ft') Sea Level Pressurized Unpressurized Aircraft Agent (For info Aircraft only) (8k ft. CPA) 12.5k ft. 14k ft. 18k ft. 25k HCFC Blend B " 0.00499 0.00371 0.00311 0.00293 0.00249 0.00185 HFC-227ea " 0.0551 0.0409 0.0344 0.0324 0.0275 0.0205 HFC-236fa " 0.0595 0.0442 0.0371 0.0349 0.0297 0.0221 Halon 1211 b 0.00224 0.00166 0.00139 0.00131 0.00112 0.000829 Halon 1211 C 0.00449 0.00334 0.00281 0.00264 0.00225 0.00166 Halon 1301" 0.0260 0.0193 0.0162 0.0153 0.0130 0.00968 a Values are based on safe human concentrations. See reference report appendix 3, paragraph 7m of this AC.
b This value is based on the NOAEL Halon 1211 concentration of 0.5%.
c This value is based on the LOAEL Halon 1211 concentration of 1.0%.
d Safe human concentrations are not available for Halon 1211. The Halon 1211 LOAEL concentration of 1.0% (v/v) has been shown to be safe for humans. See reference report in note a above. However, the safety factor is smaller than that set for the other agents.
Figure 6. Multiplication Factors (MF Ventilated) for Ventilated Compartments Air Change Time, + (minutes) HFC-236fa 1 17 12 18 13 121 12 18 1 Halon 1211' Halon 1301 a No MF Ventiluted is applied if air change time is greater than 6.
b More conservative MF Ventilated than actual. Based on Halon 1301 MF Ventilated-
(3) Safe-use selector curves may be used in lieu of Figure 5 and 6 above. They can be found in the reference report mentioned in paragraph 2a(2) above and can be used to obtain safe-use W/V for ventilated aircraft.
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Appendix 4
(4) Actual concentrations encountered by occupants may be significantly lower than the perfect mixing model concentrations, depending on agent stratification, air distribution, and geometry of a particular aircraft/aircraft compartment and the height and position of the occupant. A correction ultimately may be made for stratification/localization which may further increase the calculated safe-use concentration. See chapter 4, paragraph 4b(3) of this AC. The FAA will publish a report with limited examples of stratification and a methodology for use in determining this correction to adjust the safe-use concentrations for those examples. This report will include a comparison of actual post-discharge halocarbon concentration histories with perfect mixing concentration histories. The safe-use concentrations can be determined from the kinetic solution of equation 6 of the report referenced in appendix 3, paragraph 7m of this AC along with the target arterial concentrations and/or other calculation guidance provided in that report.
b. Minimum Safe Volume. This guidance may be used in place of the safe-use W/V guidance. It establishes a baseline minimum volume at which an extinguisher may safely be used, assuming perfect mixing.
The minimum safe volume is a useful tool for comparing the toxicity of hand extinguishers with the same fire fighting performance, i.e. the same U.S. - UL rating. The lower the minimum safe volume used, the comparatively less toxic the agent. Therefore, the safest extinguisher of a given rating has the lowest minimum safe volume. Obtain the minimum safe volume of an extinguisher by dividing the charge weight of the agent in the largest extinguisher in an aircraft compartment by the safe-use agent W/V for the appropriate altitude and ventilation.
Charge Weight Agent MinimumSafeVolume = Where, F is the safe-use W/V obtained from Figure 5 and 6 of this AC.
(2) Extinguishers in Unventilated Compartments. The minimum safe volume for unventilated aircraft should be used when the air change time is unknown or exceeds 6 minutes, and when multiplication factors for ventilated aircraft, MF ventilated, are not available for a particular agent. If the safe-use W/V can not be met for any of the agents, consider the relative neat agent toxicities of extinguishers in Figure 1 when selecting an extinguisher. See Figure 7 for the minimum safe volumes for extinguishers in unventilated compartments.
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