Fire Safety in Buildings Module 1 Part A, VTU, 3rd Sem 21CV385

1. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere
1
FIRE SAFETY IN BUILDINGS
21CV385
MODULE – 1

2. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 2
Basic Concepts of Fire Protection
Introduction
 Avoid Initiation
 If Initiated – Stop the Spread
 If Spreaded – Suppress
 Safe Refuge & Escape

3. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 3
Control of Combustion Process
• Quantity, Properties and
Distribution of Combustible
Material within the space.
• Air supply for Combustion.
• Room volume, shape and
ceiling height.
• Thermal properties of Walls,
Floor, Ceiling, etc.,
Automatic Suppression
• Fire detection and Alarm
warning.
• Automatic Sprinkler System.
• Non Electric Conduction
System.
• Carbon di-oxide System.
• Foam System.
Control by Construction
• Protect Structure Member
• Fire Resistance of Walls,
Floor, Ceilings, Doors, etc.,
• Fire-Stop Operation.
• Panel Vents and Charts.
Manual Suppression
• Fire Detection and Alarm
Warning.
• Portable Fire Extinguishers.
• Standard Fire Hose
• Fire Department Professionals
and Equipment
Methods of
Fire Control

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Fire: process of Combustion

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Fire: process of Combustion
Course of Fire
Fully Grown Fire
Fuel Depleted Fire
Flash Over

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Fire – Effect of Enclosure

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Fire: process of Combustion

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Fire – Effect of Enclosure
Ventilated Controlled Fire
Fuel Controlled Fire
Model of Pre Flash Over Fire

10. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 10
Standard Fire
T = To + 345log (8t + 1)

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Fire Resistance
A Structure should be able to withstand a standard fire for a specified time. Hence Fire resistance is defined in
terms of ‘Time”. i.e., the time up to which it will sustain the standard fire.
Collapse is one issue, but spread of fire is an equally important issue.
Fire resistance is the time during for which the element can endure the standard fire in terms if stability,
integrity and insulation.

12. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 12
Fire Resistance
Test for Integrity:
Look for Crack
Bring a standard cotton pad to the crack.
If the pad catches fire within 10 secs, the structure is said to have lost its integrity.
Test for insulation:
If the average temperature rises beyond 150°C, the structure has lost its insulation. No individual point shall
exhibit a temperature rise more than 180°C.

13. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 13
Fire Resistance
Fir severity:
Manifestation of fire – temperature.
Fire severity is defined in terms of area under the time – temperature curve.
Two fires are said to be equally severe if their areas under the time – temperature curve is same.
Area under curve = ʃ Tdt

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Fire Severity

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Fire Severity

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Fire Resistance

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Curve for Fire Resistance Design

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Fire Severity

19. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 19
Fire Severity

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Fire: Temperature in a room

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Fire: process of combustion
For points 1,2,3 and 4
Point 1 and 4 are inside the compartment,
2 and 3 are just outside.
Pressure at 1, 2 as function of y can be written
as
P1 = P0 – e1 g y
P2 = P0 – e0 g y
P1 and p0 are densities of gas inside and
outside air respectively, gas on going out
would expand and attain nearly same density
as outside air.

22. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 22
Fire: process of combustion
Pressure at 3, 4 as a function of y can be
written as given below
P3 = P0 – e0 g y
P4 = P0 – e4 g y
For negative values of y P3 and P4 greater
than P0

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Barnolies equation (recap)

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Barnolies equation
Applying force balance

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Barnolies equation

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Barnolies equation

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Fire: process of combustion
For gas flow from point 1 to 2
V1 will be zero (no net directional flow), the pressure difference is due to confinement of hot
gases inside the compartment and once it is out to point 2 at atmosphere, it would expand & the
density would change to nearly atmospheric condition. Hot gases flows so gas density is used in
denominator

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Fire: process of combustion

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Fire: process of combustion

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Fire: process of combustion

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Fire: process of combustion

32. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 32
Fire: process of combustion

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Fire: process of combustion

34. SUPREETH, ASST. PROFESSOR, B.I.E.T, Davanagere 34
Fire: process of combustion
For non-stoichiometric burning

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Fire: process of combustion

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Fire: process of combustion

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Fire: process of combustion

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Fire: process of combustion
The ratio works out to be 0.34 – 0.42 for ɸ = 1, generally the ratio is 0.3 to 0.5
Using typical value of r = 5.7 kg of air for wood, typical ratio of po/pf varying from 1.8 to 5

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Fire: process of combustion