Fire Protection Systems Flashcards
Class A Fires
Ordinary Combustibles, Wood, Paper, and Cloth.
Class B Fires
Flammable Liquids, Grease, Oil, Pain, and Solvents.
Class C Fires
Live electrical equipment, Electrical panel, Motor, and Wiring.
Class D Fires
Combustible Metal, Magnesium and Aluminum
Thermal switch
Bi-metallic thermal switch
How are thermal switches arranged?
In parallel to one another, in series with the indicator light.
Will a thermal switch still indicate a fire if the wire breaks?
Yes, because of the loop arrangement
How does a thermocouple function?
If all thermocouples increase in temperature at the same rate there is no voltage difference between them, and no indication is made.
How are thermocouples arranged?
In series with each other and the warning indicator.
What are three continuous loop systems?
Fenwal
Kidde
Pressure-type
How do Fenwal systems work?
Ceramic beads keep a wire in the center of the tube. Resistance decreases when the elements get hot. Element will indicate heat anywhere along the loop. Is a single conductor continuous loop.
How does a Kidde system work?
Two conductor continuous loop system. Material in the tube creates a certain amount of resistance between the wires. Overheat=less resistance. Fire=even less resistance.
How can a Kidde system be tested?
By sending power through the loop to see if there is a break or short.
How does a pressure type system work?
Held closed by sealed in helium gas pressure. Opens on loss of gas pressure.
How does a light refraction detector work?
Its a photoelectric cell with a light source, light gets reflected from the smoke into a photocell.
How are powerplant zones rated?
By airflow
How does an Ionization detector work?
Based on the strength of the ionizing beam hitting the target.
Where and why are detectors used?
Used in cargo baggage areas and lavatories. They are expected to generate lots of smoke before they would create enough heat for a heat type sensor
What is a flame detector?
Based on either infrared or ultraviolet wave lengths associated with flame.
What are the two kinds of CO detectors?
Chemical and electronic
How do fixed Halon systems work?
Stainless steel tubes to distribute extinguishing agent. Uses HRD
HRD bottles
Filled with Halon 1301 which needs pressurization gas, normally nitrogen.
What is a squib?
An explosive discharge valve
What is a yellow discharge indicator?
Fixed extinguisher system has been activated
What is a red discharge indicator?
Thermal discharge from relief valve
