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Often , though , particularly with older aircraft , an extinguisher isn ’ t listed . Or if listed , the extinguisher may no longer be available . In this case , consider FAA Guidance .
AC20-42D “ Hand Fire Extinguishers for Use in Aircraft ” and AC120-80 “ In-flight fires ” are good sources of information . Both recommend the use of “ clean agent ” fire extinguishers , and against dry chemical , dry powder or CO2 .
A note regarding Underwriters Laboratories , fire classes , fire ratings , and clean agents .
Underwriters Laboratories tests and rates fire extinguishers using standardized , repeatable tests . These ratings allow for the comparison of different sizes and types of extinguishing agents on different sizes and types of fires . Things like how long the extinguisher takes to discharge , and how far one needs to stand back from the fire all come into play . Not surprisingly , aA “ UL Listing ” is actually a minimum FAA requirement .
Dry Chemical CO2 Clean Agent
DRY CHEMICAL EXTINGUISHERS are effective , inexpensive and readily available . DON ” T GET THEM . Their fatal flaw is that they create blinding , choking clouds of corrosive dust . A blinded , choking pilot will be challenged to safely land a plane . If he does , the damage from the dry chemical will be significant . A CARBON DIOXIDE EXTINGUISHER makes no mess , and the only damage might be to electronic components due to the freezing temperature of the agent as it is discharged . The biggest negative of CO2 is that it is dangerous to use in a confined space . In addition to cooling , CO2 extinguishes fire by removing the oxygen from the air - not good for the pilot .
Having any extinguisher is better than having no extinguisher . But a clean agent extinguisher will safely and effectively put out a fire without causing any mess or damage , and without obscuring the pilot ’ s vision .
What is a clean agent ?
The National Fire Protection Association defines a clean agent as , “ any type of fire extinguishing agent that is electrically non-conductive , volatile , or gaseous , and that does not leave a residue upon evaporation .”
Clean agent extinguishers chemically interrupt the combustion process , rather than smothering the fire like dry chemical or dry powder , or by removing the oxygen like CO2 .
The graphic above identifies the most common classes of fires . “ A ” is for common combustibles , “ B ” is for flammable liquids , and “ C ” indicates that the agent won ’ t conduct electricity back to the operator . “ D ” signifies flammable metal fires and is less common .
The number preceding the fire class letter indicates its relative effectiveness . A 5B : C rated extinguisher is approximately 2.5 times as effective as a 2B : C rated extinguisher .
BEWARE of non-UL-listed fire extinguishers ! Though illegal in most states , they do exist . Any claims as to the effectiveness of a non-UL-listed fire extinguisher are meaningless because the extinguisher has not been tested to a recognized standard . Don ’ t fall for hairspray bottle type , “ fire extinguishing sprays ” or other non-standard looking , non-UL listed products . Due to the small size and feeble discharge range , they often require you remain very close to the fire as you wait for the product to discharge completely . A UL-listed fire extinguisher is designed to put out a fire from a safe distance in about 10 seconds .
Clean agents are also effective on class A , B , and C class fires — another reason why the FAA recommends them . Note , though , that while a clean agent extinguisher can be used on these classes of fires , the extinguisher itself may be too small to receive an “ A ” rating . For example , the FAA recommends a 2B : C
E3AVIATION . COM