Chapter 5: Fire Protection Systems Flashcards
what defines a complete fire protection system?
fire detection ssytem, fire extinguishing system
areas that have a fixed fire detection system and/or extinguisher system
1) engine & APU
2) cargo
3) lavatories
4) electronic bays
5) bleed air ducts
different fire detection methods
1) rate of temp rise detectors
2) overheat detectors
3) smoke detectors
4) carbon monoxide detectors
5) eyes
classes of fire
A: ordinary combustible materials (wood, cloth)
B: flammable liquids (oil, petrol)
C: electrical equipment
D: combustible metals (Mg, Li, Na)
requirements for fire detector system
1) no false warnings
2) rapid indication of fire
3) indication of re ignition of fire
4) resist damage
5) runs on DC
6) separate detector for each engine
what are the 3 common fire detector system
1) thermal switch
2) thermocouple
3) continuous loop
what is a thermal switch system?
heat sensitive units that completes electrical circuits at certain temperature
what is a thermocouple system?
two dissimilar metals with a hot junction and cold junction to measure rate of temp. rise
2 types of continuous loop system
thermistor (kiddle & fenwal)
pneumatic pressure detector
how does the pneumatic detector work?
2 sensing functions, overall avg temp & localised temp.
average temperature for pneumatic alarm to sound off
200 to 800 deg F
types of smoke detection system
1) light refraction
2) ionisation
3) optical
how does a light refraction smoke detection system work?
photoelectric cell that senses change in amount of light to send warning signal
how does ionisation smoke detection system work?
radioactive material to ionise oxygen & nitrogen, smoke particles attaches to the ions and reduces current flow
how does optical smoke detection system work?
small amount of light from LED gets to detector, if there is smoke, more light will be reflected to detector
