Passive Protection Flashcards
What is the primary purpose of passive fire prevention systems?
- To contain fires
- Prevent smoke and flame spread through compartmentation
- Protecting structural elements.
Compartmentation includes fire-rated walls, floors, and ceilings.
What does compartmentation in passive fire prevention involve?
Fire-rated walls, floors, and ceilings to divide a building into manageable sections.
This helps to restrict fire to the area of origin.
What is structural fire protection?
Coating load-bearing structures like steel beams with intumescent coatings to increase their fire resistance.
Intumescent coatings expand when exposed to heat, providing an insulating barrier.
How does passive fire protection differ from active fire protection?
- Passive fire protection contains the fire & prevents its spread,
- Active fire protection involves detecting, alerting, & stopping a fire.
Active examples include portable extinguishers and smoke detectors.
What is the principle of containment in passive fire protection?
To restrict a fire to the room of origin using fire-resistant construction materials.
This minimizes the risk to other areas of the building.
What is a fire compartment?
An area totally separated from the remainder of the building by continuous fire resisting construction.
It forms a complete barrier to heat and smoke from a fire.
What are the two aspects of compartmentation?
- Containment of Heat and Smoke within Compartment
- Isolation of Occupants within Compartment from Heat and Smoke
What is required for service rooms like kitchens and generator rooms in terms of fire compartmentation?
They must be enclosed in one-hour and two-hour separations depending on the risk involved.
This helps contain potential hazards.
What materials should compartment walls be constructed from?
Non-combustible materials.
They must be able to contain fires for a specified period.
What is the role of fire-resistant materials in fire compartment walls?
To seal gaps and cracks to prevent fire and smoke from progressing through the compartment wall.
How does fire typically spread within a building?
Through openings needed for access, such as doors and provisions for electrical and mechanical services.
It usually does not spread by burning through walls or floors.
What is the requirement for fire doors in relation to fire compartments?
A fire door must have the same fire resistance as the fire compartment wall.
Fire doors must be self-closing to limit fire spread.
What must fire protected shafts, pipes, and ducts have?
The same fire resistance as the fire resisting compartment wall they pass through.
They must be treated with fire-resistant materials.
What is a fire damper, and what is its function?
An automatic shutter that closes to prevent the passage of flames and smoke when a fire occurs.
It is typically held open by a fusible link that melts at around 72°C.
What is fire stopping and its importance?
Fire stopping is needed to prevent the passage of flames, heat, and smoke through openings in compartments.
It must be made of non-combustible materials like cement mortar, gypsum-based plaster, or mineral wool.
What is the definition of fire resistance in building structures?
The ability to satisfy stability, integrity, and insulation criteria while performing its required function over a defined period such as 1-hour or 2-hour.
The three criteria are essential for assessing the fire resistance of structural elements.
What are the three criteria for fire resistance?
- Stability: must not collapse and support its load
- Integrity: must not develop holes or cracks for flames and gases
- Insulation: must not allow excessive temperature rise on the unexposed side
These criteria ensure the safety and functionality of building elements during a fire.
What criteria must walls in building structures satisfy?
- Stability
- Integrity
- Insulation
Walls are critical for maintaining fire compartments within a building.
What criteria must floors in building structures satisfy?
- Stability
- Integrity
- Insulation
Floors support loads and prevent fire spread, necessitating these criteria.
What criteria must doors in building structures satisfy?
- Integrity
- Insulation
Doors primarily function to limit smoke and heat transfer.
What is a fire resistance rating?
A measurement of fire resistance assigned to an element of building structure based on testing, expressed in hours or parts thereof.
For example, a wall tested for 75 minutes receives a rating of one hour.
What are the three failure criteria for fire resistance testing?
- Stability: must perform load-bearing function without collapse
- Integrity: must not develop cracks or holes allowing smoke or gases
- Insulation: temperature on the cold side must not exceed specified limits
These criteria ensure the tested element meets safety standards during a fire.
At what temperature does steel start to lose strength and stiffness?
About 400 °C.
At 600 °C, structural steel can lose two-thirds of its original strength.
What fire protection methods are used for structural steel elements?
- Sprayed on compounds
- Boards
- Mineral wool
- Intumescent paint
These methods help maintain load-bearing capacity during a fire.
Fill in the blank: The fire resistance of an element of structure must satisfy the criteria of ______, integrity, and insulation.
[stability]
True or False: Floors and walls in building structures must satisfy the same fire resistance criteria.
True
Both elements are essential for maintaining safety and functionality during a fire.
What happens to building materials under extreme heat?
They can cause total collapse and destroy a building, necessitating heat limitation in fires.
Understanding the effects of fire on materials is crucial for fire safety design.
Steel under extreme heat
- Weakens at 400°C
- Loses two-thirds of its strength by 600°C (common in domestic fires).
Fire Protection of Steel
- Sprayed compounds
- board
- mineral wool
- intumescent paint
Concrete in high temperature
- Fire-resistant but relies on steel for strength.
- Steel must be insulated cuz overheating.
- Low thermal diffusivity slows heating.
- Reinforcement bars must be deep enough.
- High heat can cause explosive spalling.
Wood in extreme temperatures
- Weakens at high temperatures.
- Burns and chars at a constant rate.
- Char layer protects inner wood.
- Timber resists fire well and can be oversized for safety.
- Usually left unprotected.
Bricks in high temperatures
- one of the best fire-resistant materials
- cuz already been kiln-fired at high temperature during manufacture
What is fire severity?
Defined as the potential of a fire to destroy or damage a building, its contents, & the adjacent property.
It is determined by the maximum temperature achieved and the duration when the maximum temperature persists.
What are the two parameters related to fire severity?
- Maximum temperature achieved
- Duration when the maximum temperature persists
These parameters help assess the destructive impact of a fire.
What factors affect fire severity?
- Nature of the fuel
- Amount of fuel per unit area
- Arrangement of fuel
- Size and shape of room
- Area and shape of windows
- Thermal insulation of walls and ceiling
The first three factors relate to combustible contents, while the last three relate to building design.
What is meant by ‘nature of fuel’ in the context of fire severity?
The nature and composition of combustible materials vary according to the type of occupancy, affecting heat release during burning.
It includes how much heat is released and how quickly.
What is a fire load?
The combustible contents of a building, often expressed in terms of the ‘wood equivalent’.
It helps in assessing the potential severity of a fire.
What is fire load density?
Fire load density is defined as the fire load per unit floor area, expressed in terms of wood equivalent.
It is crucial for determining building design to withstand fire effects.
True or False: A low fire load density is important in limiting the severity of a fire.
True
Lower fire load density can help reduce the destructive potential of a fire.
Fill in the blank: The fire load in a building depends on the _______.
[size of the building]
Larger buildings typically contain more combustibles.
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What determines how a small fire spreads among combustible materials in a room?
The placement and separation of combustible materials
Closer packing of items leads to faster fire spread.
What happens to flames when combustible items are tall?
Flames reach the ceiling quickly and spread sideways
This is due to the rapid sideways movement of flames under a ceiling.
How does the surface area of combustible materials affect their burning rate?
Larger exposed surface area leads to faster burning
Wood shavings burn more quickly than solid wood blocks.
What are the two factors that control the severity of a fire in a building?
Air supply and loss of heat
What is a ventilation-controlled fire?
A fire where the burning rate increases with the size of the window opening
What occurs when a fire transitions from ventilation-controlled to fuel-controlled?
The burning rate is determined by the nature and placement of combustible materials
What is the fire load per unit window opening value for wood crib fires at the transition point?
160 kg/m2
What does Q represent in the context of ventilation-controlled fires?
The amount of ventilation air available for combustion
What factors affect the amount of ventilation air for combustion?
Window area (A) and height (H)
How does the size and depth of a compartment affect fire severity?
Larger compartments allow more combustible materials, deeper compartments lead to higher temperatures
What is the effect of low ceilings on fire spread?
Flames reach the ceiling quickly, facilitating spread
What is flame spread?
The propagation of flame across the surface of a material
What are the classifications of flame spread?
Class 0, Class 1, Class 2, Class 3, Class 4
What does Class 0 represent in flame spread classification?
Surface of no flame spread
What is required for wall and ceiling linings in exit areas?
Class 0 performance rating
What materials can achieve a Class 0 rating?
Non-combustible materials such as plaster, brickwork, blockwork, or plasterboard
What is the minimum surface spread of flame rating for roof covering?
Class 1
Why are buildings classified into different purpose groups?
To identify risk elements and apply appropriate fire protection measures
What is the function of Purpose Group I?
Small Residential
What type of buildings are classified as Purpose Group III?
Institutional, such as schools and hospitals
What is the purpose of Purpose Group VI?
Factory Manufacturing
Fill in the blank: Purpose Group VII includes _______.
Place of Public Resort, such as cinemas and restaurants
True or False: Combustible materials like timber can meet Class 0 performance.
False
Provision for External Access to Building for Firefighting
- Fire access panels enable firefighter entry.
- Includes wall openings, windows, balcony doors, and glazed panels.
- Must be openable from inside and outside.
- Keep clear of obstructions (1m minimum).
- Should be in occupied spaces, not dead ends or restricted areas.
- Marked with a red triangle and “Firefighting Access - Do Not Obstruct.”
- Spaced max 20m apart.
Accessibility of Site to Fire-fighting Appliances
- Access road: For fire trucks to enter building compounds.
- Accessway: Paved road for firefighting operations, with higher load and width.
- Must be 6m wide and support 30-ton load.
- Openings along walls for access.
- Marked with “Keep Clear” signs.
- Within 18m of breeching inlet for buildings over 10m high.
Prevention of External Fire Spread from one Building to Another Building
- Buildings use non-combustible materials and limited openings.
- Fire spreads by direct flames, radiated heat, or flying embers.
- <1m from boundary: Flames are the main risk.
- > 1m from boundary: Radiation is the main risk.
- Radiation spread depends on fire size, distance, and heat-transmitting surfaces.
- Risk factors: space separation, wall construction, and roof combustibility.
