연소 및 소화[산업안전보건교육]

Main ideas & lessons (combustion + fire/extinguishing)

1) Why fire matters (context)

Fire enabled early humans to:

• See at night (light)
• Survive colder regions (heating)
• Live more hygienically by cooking food (longer lifespan)
• Expand into diverse environments, contributing to varied civilizations

2) What “combustion” is (core definition)

Combustion: a substance reacts with oxygen in the air to burn, emitting light and heat.

Three required conditions

All must be present:

• Combustible substance (fuel)
• Oxygen (oxidizer)
• Sufficient temperature (for spread/ignition)

If any one is missing → combustion will not occur.

3) Flame color vs temperature

• Flame becomes brighter as temperature rises.
• Reported progression (as stated in subtitles):
  • Dark red (3850)
  • Red (1100)
  • Yellowish-red (1500)
  • Golden (100) (Values appear inconsistent due to auto-captioning, but the key point—brightness/color increases with higher temperature—remains the lesson.)

4) Complete vs incomplete combustion

Complete combustion

• Oxygen supply is sufficient
• Produces mostly carbon dioxide (CO₂) and water (H₂O)
• Produces more heat

Incomplete combustion

• Oxygen is insufficient or temperature is too low
• Produces smoke and carbon monoxide (CO)
• Smoke includes many unburned carbon particles

5) Types/forms of combustion (surface vs flame)

Surface combustion / surface fire

Needs:

• Combustible matter
• Oxygen
• Ignition source

Flame combustion / flame fire

Builds on surface combustion but also requires a:

• Smooth chain reaction

Key points:

• Combustion speed is fast because gases burn via chain reaction
• Requires formation of a combustible gas mixture

Solid vs liquid vs gas combustion

Solid combustion

• Surface combustion (e.g., charcoal burning)
• “Emergency combustion” (candle-like): solid vaporizes, resulting gas burns; glowing with little/no flame from the solid itself

Liquid combustion

• Liquids (alcohol, acetone, petroleum) are flammable but must vaporize first
• Behaves like gaseous combustion
• Ignites easier than solids; burns more controllably; less ash

Gas combustion

• Produces a flame
• Flame types:
  • Diffusion combustion: gaseous fuels (H₂, acetylene, propane, butane) burn as they mix with air oxygen
  • Fire ignition (flame ignition): pre-mixed fuel/air in a sealed container, then ignited (Examples mentioned: gasoline engine combustion, “astilting,” oxygen welding equipment.)

6) “Ignition point” and related temperature terms (important metrics)

Combustion point (ignition point)

The lowest temperature where a combustible substance begins to burn without directly contacting an existing flame.

• Lower ignition point → easier to ignite/burn
• Example mechanism: friction heat from rubbing wood rises until reaching ignition point, then flame appears.

Natural combustion / spontaneous combustion (wording in subtitles)

• A substance spontaneously generates heat in air via decomposition/adsorption/oxidation
• When it reaches the ignition point → it combusts naturally

Factors that lower ignition point

• More complex molecular structure
• Higher oxygen affinity
• Low thermal conductivity
• Lower calorific value (as stated)
• Higher “scientific activity level” (as stated; likely refers to higher reactivity)

Distinct temperature terms mentioned

Flash point

• Lowest temperature where flammable vapors are generated within the combustion range
• Used as a risk metric
• Example: gasoline has a lower flash point than diesel → considered more dangerous

Fire point / combustion continuation point (as described)

• Temperature where a flammable liquid can keep burning after the ignition source is removed
• ~10°C higher than flash point (as stated)
• Allows combustion to continue for more than 5 seconds

7) Abnormal fuel combustion phenomena (safety hazards)

Flame-back (flashback)

• Flame penetrates into fuel/mixture when ejection speed > combustion speed
• Examples:
  • Gas welding: clogged/overheated burner → flame may reverse into acetylene coating
  • Furnaces: flame may reverse inside burner
• Safety: install a stabilizer to prevent serious accidents

Extinguishing / flame goes out

• Causes listed: burner overheating, mixing/cutting too tight, ejection velocity dropping below combustion velocity, high pressure, nozzle corrosion enlarging the hole

Flare-off (opposite behavior)

• Flame detaches from nozzle and burns when ejection velocity > combustion velocity
• Can prevent complete combustion
• Increasing flow rate can cause flame lift or extinguish

Bluffing state (as described)

• If fuel ejection velocity increases or air flow becomes excessive:
  • Flame fails at the nozzle, detaches, extinguishes

8) Spontaneous combustion (how it happens & prevention)

Spontaneous combustion

• Substance exposed to air ferments/oxidizes and ignites at room temperature
• Mechanism: reaction heat builds via oxidation, decomposition, adsorption, microbial adsorption, etc.

Conditions that promote it

• High temperature in the natural-combustion region
• Low thermal conductivity
• High heat generation
• Large surface area
• Poor air permeability
• Catalytic substances present

Prevention (as stated)

• Lower humidity to disperse heat and reduce surrounding temperature
• Provide good ventilation
• Avoid contact with air using inert gas injection

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Fire extinguishing: methodology & types (detailed bullets)

9) Principle of fire extinguishing

Fire extinguishing prevents continued combustion by removing one or more of the three combustion elements:

• Fuel (combustible substance)
• Oxygen source
• Ignition source

10) Types of extinguishing agents & methods

A) Cooling extinguishing

• Apply large amounts of water to:
  • Cool the ignition source
  • Lower smoke temperature below the immediate ignition/sustaining threshold
• Uses latent heat of vaporization
  • Water latent heat stated: 539 calories/gram

B) Suffocation (oxygen-cutoff) extinguishing

• Reduce oxygen concentration in air from about 21% → 15% or less
• During suffocation: oxygen concentration required is stated as 12%–15%
• Example: extinguish an alcohol lamp by covering it with a lid (cuts oxygen supply)

C) “Erasing” extinguishing (removing the fire)

• Remove burning material / stop fuel supply
• Examples:
  • Turn off the gas stove valve
  • Forest fire: fell trees ahead of fire spread
  • Candle: blow out flame
  • Oil field fire: use explosives to extinguish flames
  • Electrical fire: rapidly cut power
  • Cover smoke with inert materials to separate from unburned parts
  • Treat wood with flame retardants to suppress flammable gas generation

D) Chemical extinguishing (chain reaction inhibition)

• Block the chain reaction via catalytic action of the extinguishing agent
• Effective against flame combustion, less effective for surface combustion
• Agents inhibit chain reactions and may also remove fuel via oxygen-related actions

E) Dilution extinguishing

• Spray large amounts of water to lower concentration of flammable liquid extinguishing agents (acetone, ether, esters)

F) Water spray / mist systems (special form)

• Mist-like spray forms a non-combustible film on the fire surface

G) Coating extinguishing

• Spray carbon dioxide heavily to form a deep, heavy gas layer that blocks combustion
• CO₂ noted as heavy gas (about 1.5× air’s specific gravity)

11) Extinguishing methods by water discharge style (as described)

Three water forms:

• Solid spray
• Red spray (sprinklers)
• Mist spray

Effects:

• Solid/red spray: cooling
• Mist/water spray: cooling via dilution and emulsification

Additional notes:

• CO₂ described as “suffocating + coating”
• Halogen compound powder described with suffocating/catalytic effects

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Fire extinguisher classification (as described)

12) Classification by extinguishing mechanism type

Pressurized type

• Extinguishing agent + non-combustible gas in a container
• Released by internal pressure
• Except CO₂ extinguishers: pressure gauge included
• Gauge interpretation:
  • Green light: normal
  • Left of green: agent may not discharge properly (insufficient charging pressure)
  • Right of green: risk of nozzle damage/maintenance issues (overcharging)

Compressed type / pressurized as described

• Pressurized container inside/outside maintains required discharge pressure

13) Classification by “capacity unit”

• Determines extinguisher/fire equipment installation, maintenance, and safety management
• Approved per legal standard (Article 36, Paragraph 1 mentioned)
• General grouping:
  • Small extinguishers: capacity unit ≥ 1 and less than large class
  • Large extinguishers: carry stand + wheels; stated range examples:
    • 10 rounds for some types
    • 20 rounds for Class B fires or more (as stated)

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Extinguisher types and key points (by agent)

14) Water extinguishers

• Manual pump: discharge water by pumping
• Stored-pressure type: water + air in a pressurized tank
• Pressurized type: water discharged using gas pressure from a separate container (for larger extinguishers)
• Principle: cooling
• As water evaporates:
  • Volume expansion described (~1700×)
  • Acts as dilution because it becomes non-combustible steam

15) Acid-alkali (acid + bicarbonate) extinguishers

Pre-emptive type

• Sulfuric acid in top resin container
• Sodium bicarbonate in main body
• Opening/mixing releases and triggers discharge through outlet

Discharge type

• Ruptures sulfuric acid container
• Reaction generates CO₂ pressure to spray sodium bicarbonate solution

Uses:

• Dilute sulfuric acid + sodium bicarbonate → CO₂ generation

16) Specialized reinforced liquid extinguisher (potassium carbonate water-based)

• Non-freezing down to around -20°C (per subtitles; later mentions also support use at 8°C)
• Suitable for Class A, B, and C when capable of non-combustible firefighting
• Non-combustible effects via water action; secondary prevention effect

17) Carbon dioxide (CO₂) extinguisher

• Agent requirements:
  • CO₂ content 99.5% or higher
  • Moisture 0.05% or lower
• If moisture ≥ 0.05%: freezing/nozzle clogging risk
• Extinguishing mechanism:
  • Cooling coating action of CO₂
  • Dry-ice cooling effect mentioned; suitable for oil fires
  • Also suitable for electrical fires due to electrical insulation
• Safety: hold handle to avoid frostbite when grasping the discharge trumpet (horn)

18) Compound / clean-agent style extinguishers (halogen compounds)

• Agents include bicarbonate and halogen compounds (fluorine/bromine/chlorine)
• Spray vaporizes into heavy, non-combustible gas that cools and suppresses
• Subtitles state:
  • Generally uses Halon 1301
  • Not generating toxic gases (as stated) compared to some other types
• Ozone note:
  • Chlorine and bromine are said to destroy the ozone layer
  • Conventional use continues; new production restrictions mentioned
  • “Clean agent fire extinguishers” using rarely used chlorine/lead mentioned

19) Powder fire extinguishers (most widely used)

• Dry fine powder treated to retain moisture resistance and fluidity
• Types mentioned:
  • Type 1: sodium bicarbonate
  • Type 2: potassium bicarbonate
  • Type 3: ammonium phosphate
  • Type 3 variant: potassium bicarbonate + urea
• Types primarily used: 2 and 3 (general fires, wettable powders, electrical fires)
• Main effects emphasized:
  • Suffocation and ignition suppression (wording in subtitles)
• Other effects mentioned:
  • Cooling and “extinguishing science” (as spoken)

20) Foam fire extinguishers

• Mix extinguishing agents with water solution to produce foam
• Foam cuts off air supply
• Suitable particularly for flammable oils (e.g., gasoline, chemicals)
• Requirements described:
  • Foam must be lighter than oil, adhere to ground
  • Cohesive/stable under wind
  • Strong heat-resistant film
  • Good fluidity
• Effects emphasized:
  • Suffocation + cooling

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Speakers / sources featured (identified)

• Lee Yeon-su (introduced as the instructor/speaker: “with Lee Yeon-su El”)
• Other learners (mentioned generally as participants asking questions; no names given)
• No other named individuals are clearly identified in the subtitles.