Video Summary - 06. Medios de Escape y Evacuación de Humos y Gases

Main ideas and lessons (class on passive evacuation and smoke/gas control)

Means of escape (passive protection strategy)

Exit routes and building exits are designed to ensure correct, rapid evacuation during disasters such as earthquakes or fires.

Escape route in high-rise buildings

Evacuation typically routes occupants through the stairwell. The design must match the building case by defining layout, number, and dimensions.

Escape route structure (3 segments)

First horizontal segment: from any point in the building to the stairwell.
Vertical segment: the stairwell itself
- Must never be an elevator, since elevators can malfunction and are a fire hazard.
Second horizontal segment: from the staircase to the outside exit.

Stairwell as the safest evacuation backbone

The stairwell is designed to separate floors, preventing movement of smoke, gases, heat, and fire.

Practical examples used

Lepark Figueroa (Buenos Aires): circulation corridors leading to the stairwell.
Renoa Towers (Puerto Madero, Buenos Aires): typical floor circulation to the stairwell and direct exit at ground level.

Signage is mandatory along the full escape route

Signs must guide users horizontally and vertically to emergency exits and stairways, including basement levels.

Jurisdictional regulations + calculation methods

The class applies local regulations (cited laws/ordinances) and demonstrates calculations for:

Exit route widths (using “units of outlet width”)
Free path distances (e.g., ≤ 40 m)
Stair geometry and fire-resistance requirements

Smoke and gas evacuation/control: conceptual lessons

Why smoke control matters

Smoke is a primary cause of fire deaths and rapid spread. Control systems aim to:

Protect people
Enable safe evacuation
Prevent fire spread
Reduce structural impact from heat (to improve survivability)

Smoke control strategies discussed

Often combined:

Extraction
Dilution
Compartmentalization / confinement
Pressurization

Pressurization and smoke/gas evacuation systems in high-rises

Stairwell pressurization keeps stairs usable by preventing smoke ingress.
A smoke and gas evacuation system (COVE-like concept) protects stairwells by extracting smoke and supplying clean air, with strict placement rules.
The class also includes a step-by-step duct sizing example, using:
- area
- smoke volume
- draft speed
- required removal time
- resulting duct dimensions

Methodology / instruction-style content (detailed bullet points)

A) Escape route components and design rules

Define the escape route as 3 segments

Horizontal segment #1: from any occupied point to the stairwell (via circulation corridors).
Vertical segment: the stairwell.
Horizontal segment #2: from the stairwell to the building exterior.

Elevator prohibition

Elevators cannot be the vertical segment in means of escape.

Stairwell enclosure & fire separation

Stairwell enclosure must use a fire-resistant system to allow evacuation time:
- Minimum rating: F60
- Recommended: F120 (stated as no mechanical changes during 2 hours exposure)
Perimeter structure may be transparent only if it meets fire resistance (F60).
Stairwell must not serve any other purpose than evacuation and firefighter access.

Stairwell geometry and safety constraints

Stair corners: 45° beveled corners mentioned.
Elevator entrance cannot face the stairwell entrance.
Stairwell must not contain or intersect with: hydrants, ducts/openings for installations, warehouses/storage, downpipes, etc.
Upper-floor and basement arrivals at the exit level must be through separate places to avoid crossing flows.

B) Signage requirements for means of escape

General rule

All escape routes must have proper signage along the entire length, including directions:

Toward emergency exits
Both horizontal and vertical

Sign type/standard (IRAM 105)

Use illuminated signs with pictograms and colors per IRAM 105.

Sign characteristics

Rectangular or square
Green background covering at least 50%
Standardized pictogram (person evacuating) and white letters
Direction indicators toward the escape means

Spacing / dimensioning

Dimensions vary by observer distance.
Signs are extended every 10 m (based on observer position from the previous sign).

Visibility under adverse conditions

Must remain visible in lighting failures or smoke conditions.
Corridor axes/directions can be reinforced using photoluminescent tapes or paint.

Placement in the example

Signs indicate the route at intersections/turns to the exterior.
Basement signage leads to the stairwell.
Vehicle ramps may serve as exits only if allowed by layout (example notes a freight vehicle elevator preventing use).

C) Regulatory calculation for exit width units (practical work framework)

Jurisdiction referenced

San Miguel de Tucumán ordinance 251/74
Municipal digest
National labor safety law 19,587 and decree 351/79, annex 7

Step 1: Determine unit values for exit width

Depends on:

Exit coefficient
Exit time
Number of people to be evacuated

Step 2: Exit coefficient

Defined as people per unit of exit width
Standard value: 40 people

Step 3: Exit time

Evacuation time for those people
Fixed value: 2.5 minutes

Step 4: Determine number of people to evacuate

Use floor area and occupancy factor:

Theoretical people = floor area / occupancy factor
Floor area is computed as:
- exclude bathrooms and vertical circulation
- then adjusted across floors
Occupancy factor comes from standard tables (example uses office → 8 m²/person)

Step 5: Calculate required exit width units

Units depend on the ratio of:
- (people to evacuate) / (exit coefficient × exit time)
Rounding rule: if fractional units are > 0.5, round up
Example: 2.33 units → adopt 2 units

Step 6: Decide number of escape routes / widths

If required units equal 2, verify means of escape width of 1.10 m (minimum).
If unit value exceeds 4, provide more than one means of escape.

Additional ground-floor rules

Provide at least two exit doors if:

premises hold > 200 people, or
free path to an exterior exit is > 40 m

Other rules:

Doors should be as far apart as possible
Route measured from furthest point; must avoid crossing fixed furniture

D) Free path and stair placement constraints

Maximum distance to stairwell (upper floors): any point must be ≤ 40 m from the stairwell.
No-obstacle free path: stair location must allow an unobstructed route and avoid potential fire-front impact.
Verification method (example):
- identify furthest points from the stairwell
- confirm route ≤ 40 m assuming use of a single stairwell
Ground floor:
- verify free paths also do not exceed 40 m
- large-capacity spaces require two exit doors

E) Stair geometry and design constraints (from standard explanations)

Riser and tread limits

Max riser: 18 cm
Max tread: 26 cm
Functional relationship constraint:
- tread + riser = 60 to 63 cm (as stated)

Stair configuration principles

Straight sections can contain up to 21 risers before a rest section.
Landings must match the width of steps / exit width unit.

Handrails

Located on both sides of the section and landing.
Must be continuous with no sharp edges.
If exit width units > 3, add a center handrail.

Allowed/non-allowed stair shapes

Means-of-escape staircases cannot be circular or offset (may hinder evacuation).

Example stair calculation (as demonstrated)

Use maximum riser 18 cm
Example “adopts 16 constellations” → resulting in 15.15 → adopt 16
Riser computed → 17.5 cm (within limit)
Tread computed via required relationship → 26 cm
Landing width matches exit width unit (example uses 2 units → 1.10 m rest landing width)

F) Additional types of auxiliary escape aids (non-main but discussed)

External auxiliary stairs

Located outside
Kept away from openings/windows that could admit fire/heat
No perimeter wall (as stated)

Vertical “cat stairs”

Acceptable in specific cases (e.g., basement to ground when space is insufficient)
Not for long stretches as a primary escape route
Must use non-combustible materials
Minimum width 45 cm, separation 15 cm from wall
Minimum exit space 75 cm, free space on both sides of axis 40 cm

Escalators

Can be used only if they stop in accidents.

Ramps

Non-slip surface
Max slope 12% to be considered an escape route means

Smoke and gas evacuation/control: conceptual framework + methods

A) What smoke/gas control is trying to achieve

Smoke is defined as:
- visible mass of suspended solid/liquid particles plus hot vapors/gases and mixed air
Smoke leads to human losses by:
- reducing visibility
- containing toxic particles
- accelerating fire spread dynamics

Goals during smoke extraction/control

Protect people
Facilitate safe evacuation
Prevent fire spread
Reduce high-temperature damage to improve evacuation survivability

B) Hot smoke / cold smoke zones (flow/stratification concepts)

Hot smoke zone:
- smoke rises toward the ceiling
- cleaner/less polluted air descends to lower parts
Cold smoke zone:
- movement reduced by transfer/combined effects with other elements
- movement influenced by wind and ventilation/AC/heating
- behaves like general pollutant transport

C) Smoke control methods (explicitly listed)

Extraction
Dilution
Compartmentalization / confinement
Pressurization

Extraction (how it works)

Create an upward negative pressure gradient using:
- cyclones or fans
- fans automatically linked to manual fire detection/alarm
Smoke removal ducts may be:
- purpose-designed (smoke wells/towers), or
- reuse existing ducts (not recommended unless complementing other installations)
Recommended for:
- underground/poorly ventilated buildings
- tall buildings, often combined with pressurization

Dilution (how it works)

Maintain acceptable smoke concentration where smoke leaks from adjacent spaces.
Effective when smoke entering is small relative to protected volume or air purge rate.
Can help firefighters clear smoke after fire.

Compartmentalization / confinement

Retain smoke where it is not harmful, then move it outside.
Preferred strategy: retain smoke in the room of origin.

Pressurization (how it works)

Inject clean air to prevent smoke infiltration via positive pressure.
Can be implemented in:
- stairwells
- elevators
- protected sector pressurization and COVE-related systems

D) Stairwell pressurization system: components and key requirements

Core elements

air booster unit (with backup fan if needed)
differential pressure sensor
frequency-controlled fan programmed for differential pressure control
optional control panel housing these components

Performance/parameter constraints

Possible double air intake at terrace/high level; intakes on opposite perimeter positions
Maximum pressure difference: 50 Pa (considering all closed box doors)
Minimum pressure differential: 10 Pa (considering only the box door open at exit level)
Force to open access door (pressurized) must not exceed 100 N
Airflow velocity at open entrance to fire level must be ≥ 0.75 m/s
System start via detection system (automatic or manual alternative)
Power supply must survive fire (safety circuit not affected by general power cut-off)

Standards referenced

Examples mentioned: Covening 1018/78, 12,101/6, NFPA 92.

Limitations/considerations

Real systems may not fully meet standards
Common issues: insufficient air injection and poor pressure control
Narrow margins: may require relief grilles, injector speed variators, etc.
Must include maintenance and be evaluated after installation
Due to vulnerability, it should not replace passive measures (e.g., antechambers); it’s reinforcement only when passive solutions are impossible

Smoke and gas evacuation system (COVE-like) — structure, placement rules, sizing method

A) System purpose and placement restrictions

Purpose

A combined air injection mechanism that:

drafts/extracts smoke column
removes common smoke and combustion gases above room height
protects stairwells to give occupants time to evacuate

Where it may be installed (strict)

only in landing/protected space before stairwell entrance (safe sector), or
in the anteroom to the stairwell if needed

Not permitted

direct communication with the fire compartment
direct relation to the stairwell (as stated)

B) System components (two-part structure)

Smoke & gas extraction section
Clean air supply section

Extraction layout

two ducts:
- one for extraction
- one for collection
plus a termination for the collection duct

Clean air supply

outside air injection duct to intake clean air

Connections

smoke extraction duct and air injection duct connect to the stairwell via grilles

C) Construction/dimensions (as stated)

Ducts made of galvanized sheet metal
Minimum duct dimensions:
- injection: 20 × 20 cm
- extraction: 20 × 20 cm
- extraction collector duct: 40 × 40 cm
Sold in sections of 1 m height

D) Extraction duct design rules (per level + duct lengths)

One conduit per level
Natural extraction up to a stated vertical duct length (subtitles suggest 15 m)
For ducts between 15 and 40 m, extraction must be forced and connected to detection systems
Required draft speed: 2.7 m/s

Allowed deviations

45° deviations allowed with max horizontal projection 1.5 m
If horizontal deviations occur:
- max distance 1.5 m
- extraction must be forced

E) Collector duct design and termination placement

Collector receives discharges from ducts of 10 floors (example)
Collector cross-section: four times extraction duct area
Termination/end cap distributes fumes in “four winds” direction

End cap location rules

On top floor:
- 50 cm above other finishes/ventilation/walls within < 4 m
If distance > 4 m:
- 70 cm above last inaccessible floor level
Roof design prevents wind currents from entering; accommodates duct openings

F) Air injection duct rules

Cross-section equals smoke extraction duct
Air intake:
- natural for horizontal sections up to 20 m (no deviations)
- longer or with deviations → forced extraction linked to detection system
45° deviations allowed, max horizontal projection 1.5 m
Openings in evacuation area must be covered by grates

Step-by-step calculation for sizing smoke/gas extractor ducts (explicit procedure)

Determine calculation area (m²)
- Calculation area = total floor area / 4
- Calculations are per floor; if floor area varies, compute each floor separately.
Determine smoke volume per “plant” (m³)
- Smoke volume = (mezzanine height split into three parts) × (calculation area)
Determine smoke removal speed / draft rate
- Removal speed depends on building function (table referred to).
- Draft velocity considered: prevailing wind 2.7 m/s.
Compute smoke flow rate (m³/min)
- Flow rate = smoke volume / smoke removal time (required by function).
Compute duct cross-section
- Duct section = flow rate / draft velocity.
Determine duct side dimensions
- For square ducts: side = √(duct cross-section)
- Minimum size constraint: at least 20 × 20 cm.

Smoke/gas example calculations (as shown)

Area of influence: 398 m²
Calculation area = 398 / 4 = 99.5 m²
Floor height: 2.8 m
Smoke volume:
- use one-third of height → multiply by calculation area