Horizontal Ventilation Rio Hondo Regional Truck

Operations Academy

COURSE OBJECTIVES

• Ventilation size-up

• Natural vs Mechanical Horizontal Vent

• Considerations for PPV

• Smoke removal methods

• High Rise Ventilation considerations

• Hydraulic Ventilation

• Coordinated Attack

VENTILATION SIZE-UP

Proper size up and

Communications

MUST be performed

before attempting

any form of

Horizontal

Ventilation!

VENTILATION SIZE-UP

• Type of Structure

• Location/Size of the fire

• Reading the smoke

• Status of fire attack team

• Communication with Attack team

• Burn time

NATURAL vs MECHANICAL

NATURAL vs MECHANICAL

• Ventilation can be done with natural or mechanical methods

• Opening and controlling doors and windows will take advantage of natural air currents

• Blowers or ejectors are used to accelerate and/or control air movement

NATURAL VENTILATION

NATURAL VENTILATION

• Simple method utilizing natural convection currents. Accomplished by opening doors, windows, skylights, etc.

• Limited in effectiveness by :

- proximity of opening to contaminants to be

removed

- number and size of openings

- direction of wind (windward, leeward)

- humidity (damp, cold weather will suppress convection currents)

Proper placement of your exhaust is key to successful natural ventilation

• Proper exhaust placement + coordinated attack = Nice save

• Poor exhaust placement + no coordinated plan = Urban Renewal Attack

Proper placement of your exhaust is key to successful natural ventilation

MECHANICAL VENTILATION

MECHANICAL VENTILATION

• Can be Positive or Negative Pressure

• Positive Pressure places a fan outside the structure and charges it with air, increasing pressure inside

• Negative Pressure places a fan inside an opening and ejects or sucks the air our, reducing pressure inside

MECHANICAL VENTILATION

• Utilizes portable fans or blowers to dramatically increase convection currents

• The fans FORCE the movement of contaminants to : -exit through pre-selected and/or controlled openings -allows the use of ventilation openings that are remote from contaminant area -overcome the effects of humidity -reduce the time necessary to ventilate a building when compared to natural means -uses positive or negative pressure

A smoke ejector is placed in a structural opening and a negative pressure is created as the heat, smoke, and toxic gases are “sucked out of the building.” Disadvantages include : contaminants are drawn through blower, and blowers must be placed in doorways and hallways

NEGATIVE PRESSURE

A blower is placed outside a structural opening and the airflow is directed to force clean, fresh, positively pressurized air inside the building. Advantages include : contaminants not drawn through blower, means of entrance/egress not blocked, and positive pressure is twice as efficient as negative pressure.

POSITIVE PRESSURE

POSITIVE PRESSURE

• Keys to Effective PPV

-Control Entrance Opening

-Control Vent Exhaust Opening

-Control flow path between the two

COMMUNICATION IS KEY!

POSITIVE PRESSURE

Blowers must be positioned so the cone of air issued from

a blower will completely cover the entrance opening

Optimum placement of blowers is

dependent upon blower size, entrance opening size and number of blowers. Large blowers must be placed closer than small blowers to properly “cone” an entrance

opening (tilting the blower 20-30 degrees can improve operation)

• PPV is most effective when the exhaust opening is between ¾ to 1 ¾ the size of the entrance opening

• Remove screens on windows – increases the efficiency of the opening by 50%

• In-Line – front blower 2 feet from opening, rear blower cones door. Larger blower in front smaller in rear

• Side-by-Side – parallel blowers, less effective than in-line, but good for large openings

Room without exhaust opening (storage room,

offices) must be vented with multiple blowers. Exterior blower is pressurizing structure and interior blower is aimed in bottom half of dead end room doorway

Multiple rooms each having their own

exhaust opening. Effective ventilation requires controlling the exhaust openings of each room individually, one at a time.

Multiple Floor Ventilation

Multiple Floor Ventilation

• Identify fire floor and any exposures

• Allow fire control systems to work

• Control Stairwells for Egress/Ingress

• Control HVAC system if possible

• Shut and control all stairwell landing doors

• Use building fire control features to assist

• Supercharge stairwell and possible fans on multiple floors

Multiple floors should be separately and individually ventilated

Multiple Floor Ventilation

Multiple Floor Ventilation

Control stairwell doors on each floor landing

• Used in situations where other forced ventilation techniques are not or cannot be used

• Performed by interior attack crews

• Can move several thousand cubic feet of air per minute without the use of specialized equipment

• Typically done after initial fire knockdown

Hydraulic ventilation uses the air drawn into a fog stream to push the

products of combustion out of a room or building

“Venturi Effect”

• Fog stream is placed on a wide angle fog pattern covering 85% to 90% of the opening

• The tip of the nozzle should be at least two (2) feet from the opening

• The larger the opening is, the quicker the ventilation will be complete

• May be greater water damage to the structure

• Increased drain on the available water supply for firefighting tactics

• Ice production in freezing temperatures

• Additional nozzle time in superheated environment after knockdown for attack crew

• Ventilation operations may be interrupted to rehab crews or fill SCBA bottles

Coordinated Attack

• 360 completed

• Communication est. Attack and Vent

• Confirmed seat of the fire

• Fire between Attack and exhaust opening

• Communicate to vent fire room

• Communicate to run PPV fan

• Extinguish/Extension

• Monitor for extension and additional fire

-Shut down if needed

Proper horizontal ventilation is one of the keys to the success or failure on any fire ground!!!!!