Hazard Classification Flashcards
What is the maximum area of coverage per hazard classification?
Light hazard 52 000 sq/f Ordinary hazard 52 000 sq/f Extra hazard(pipe scheduled) 25 000 sq/f Extra hazard(hydraulically calculated) 40 0000 sq/f High piled storage 40 000 sq/f In-rack storage 40 0000 sq/f
How many hazard occupancy classifications are there? List them and explain them. Listing by the NFPA
6 classifications.
Light hazard- low combustibility/low heat release.Low risk.Ex.office, schoolroom, churches.
Ordinary hazard group 1 - Low combustibility/moderate quantity. Stockpiles < 8 ft. Moderate heat release. Ex. Storage, parking garages.
Ordinary hazard group 2 - Moderate to high combustibility, moderate heat release; stockpiles do not exceed 12 ft. High heat release stockpiles do not exceed 8 ft. Ex.storage, parking garages, light manufacturing.
Extra hazard group 1 - High combustibility. Little/no flammable liquids
Extra hazard group 2 - Moderate to substantial combustible liquids.
Special occupancy - Designed specifically for the existing hazards. Ex. Solvent extraction plants, nitrate film.
Explain the difference between pipe-scheduled systems and hydraulically calculated systems.
Pipe scheduled- The first fire protection system, not cost-effective, the pipe was sized bigger. Just needed 25 psi to function correctly. Based on how many heads were allowed on any given pipe size.
Hydraulically calculated systems - Introduced in the ’70s, more cost-effective, smaller pipe sizes, allowed the use of the plastic pipe. Based on how much pressure and flow is lost through the pipe.
What is the Fire Point?
What is the Flash Point?
The fire point is the temperature at which liquid fuels will produce significant vapours to support combustion
Flashpoint is the minimum temperate at which a liquid fuel gives sufficient vapours to form an ignitable mixture. Vapours will flash but will not continue to burn.
What is radiation?
Radiation is when heat travels via electro-magnetic waves without any objects or gases to carry it along
*Radiation heat goes out in all directions unnoticed until it strikes an object.
What is convection?
Convection is the circulatory flow of a fluid or gases from one heated area to a cooler area due to heated air being less and rising, while cooler air descends.
What is conduction?
Conduction is the passage of heat(energy) through or within a material through direct contact
What is oxidatization? What is an oxidizer? Give examples
Oxidization is a chemical reaction at which oxygen or another oxidizer is added to an element or compound such as organic matter.
Oxygen is the most common oxidizer.
Oxidizers are not combustible but they support combustion
What is heat?
The form of energy that raises the temperature
What is the ignition temperature?
The minimum temperate to which a fuel mixed with air must be heated to start self-sustained combustion.
What are the three components of the fire triangle?
oxygen,heat, and fuel
What are the two types of heat ignition?
Pilot ignition - spark, flames, welding arcs, static discharge.
Spontaneous ignition - This is the ignition of combustible material as a result of internal heat generation.
Ex. bacteria, mould, fungi, spot heating of trapped gases.
What is the tunnel test?
What are the 5 classes relating to flame spread rating?
Measures how far and how fast a fire can spread on a specific material.
Class 1 or A 0-25 Class 2 or B 26-75 Class 3 or C 76- 200 Class 4 or D 201-500 (Unacceptable) Class 5 or E 500+
Flame spread Rating (FSR) of materials are tested and put into classes by the ____
Two laboratory tests to determine FSR are done by ___ and ____
NFPA
ASTM and UL
There are ___ methods to extinguish a fire, what are they?
temperate reduction
Fuel removal
Oxygen dilution
Chemical flame inhibition - by use of dry chemical or clean agent to disrupt the chemical reaction.
Liquid fuels are an ___ fuel
There are ___phases to achieve combustion of a liquid fuel
They are ___, ___,and ___
combustion can happen in the gas phase as a ___ but also in the ignition phase as a ____
Unstable fuel
3 phases
pre-heating, gaseous, and ignition
As a vapour but also as a liquid if a high enough temperature is reached.
There are ____ stages to a fire, what are they?
4 stages
Incipient - develops slow, invisible, can smell, little heat
Smouldering - visible smoke, no flames
Flame - higher heat, creates flames, limits smoke
Heat- lots of heat, smoke, toxic gases, and flames.
Solid fuels are a ___ fuel
There are ___ phases to achieve combustion of a solid fuel
They are ___, ___, and ____
Explain the process.
Stable fuel
3 phases, preheating, gaseous, and ignition.
Pre-heating - fuel is raised to at least 100 degrees by radiation, convection, and/or conduction.
gaseous - solid fuel to a vapour
Ignition - vapour + oxygen + source of ignition = combustion
There are ___ classes of fires
List them and explain what they’re composed of and how to extinguish them.
5 classes
Class A - ordinary combustible material. Wood, paper, cloth. Water or a multi-purpose dry chemical.
Class B - flammable liquids. Dry chemical cut oxygen
Class K - commercial food preparation. Extremely hot with the ability to reignite. Wet chemical
Class C - electrical fires. Clean agent chemical
Class D- Combustible metals. Magnesium, potassium, sodium, titanium, Dry powder absorbs heat and oxygen.
