Fire Detection

AM 211 Fire Protection 5 Days /6hrs

Twenty percent of the 1153 fatalities on U.S. transport airlines between 1981-1990 were caused

by fire

Quickie in Electricity

The planetary model of the atom

Sources of Electricity

• 1.Chemical ex. Battery• 2.Heat/Thermal ex. Thermocouple• 3.Pressure/Piezoelectric ex. Quartz• 4.Light ex. Selenium/Photo emissive• 5.Magnetism ex. Generators

• Back to the Regulations……..

• Define the following per FAR part 1:• -Fire Proof• -Fire Resistance• -Flame Resistance• -Flammable• -Flash Resistant

• -What are the requirements for aircraft upholstery per FAR part 23?

Fire Zones

(By airflow)-Class A Zone- large volume of air over/threw similarly

shaped objects

-Class B Zone- large volume of air over/threw aerodynamically clean objects

-Class C Zone- low airflow

-Class D Zone- little to no airflow

-Class X Zone- large quantity of turbulent air (Very difficult to extinguish fires in these areas)

Requirements for Overheat & Fire Detection Systems

• -prevent false warnings• -rapid and accurate indication• -indicate the fire was extinguished• -automatically reset/ indicate re-ignition• -continuous indication• -testable• -resist exposure• -indication by a light of location and audible alarm• -separate sensing elements for each engine

MD-11

Fire Detection and Overheat Systems

• Spot Type Individual switches or detectors -Thermo-switch -Thermocouple

• Continuous Loop Single detection element - Pneumatic (gas) - Thermo-resistive switch

Thermocouples

Cylinder Head Temp Thermocouple

Thermocouples for Fire Detection

-Rate of Rise Spot Detector made of two dissimilar metals that produce a small current (about 4ma) when heated.- Components : - Reference thermocouple - Active thermocouple - Sensitive relay - Slave relay - Heater (for the test circuit) - Visual and oral warning

Continuous Loop Systems

• All continuous loop systems have a single sensing element but vary in construction

• Thermal-Resistive Loops• Fenwal system• Kidde system

• Pneumatic (gas) Loops• Lindberg system• Systron-Donner System (Whittaker)• Meggitt System

Fenwal

Kidde

Pneumatic Systems• Recall from Physics:

-As a gas is heated, if the volume remains the same, the pressure will increase proportionally.

Inspections

Jetcal Analyzer

Smoke and Toxic Gas

Typical Installation

Fire Extinguishing Systems• Agents• -Halon (*1301 & 1211)• -Carbon Dioxide• Systems• -Portable• -Fixed• -conventional• -high rate of discharge (HRD)

Halon & HRD Systems• The most commonly used agent for

aircraft is Halon 1301 (bromotrifluoromethane CF3Br)

• Halon Production was banned in 1998 due to the environmental impact. Halon destroys ozone O3.

• Halon eliminates fire by displacing oxygen and may do the same in your lungs in confined areas.

Squib Cartridge

Alternatives to Halon• Many manufactures are struggling to

replace Halon with an equally effective , non-corrosive, safe agent.

• Hydro-clean agents• FE-25 by DuPont• Phosphorous tribromide (PBr3) PhostrEx• And many more……

Boeing 727

• 727 Fire Control Panel