Ventilation Part B

FVCC Fire Rescue

Ventilation Part B

Types of Ventilation • Horizontal Ventilation: Use of doors and windows to ventilate across the floor of a building. Especially, when there is not a roof directly above fire floor.

• Opening doors/windows between advancing firefighting crews and established ventilation points, reduces intake of fresh air from opening behind firefighters

Types of Ventilation • Horizontal ▫ Advantages  Uses openings  Uses natural air currents

▫ Disadvantages  Depends on natural air currents  Routing may expose other parts of the building  Same routes used by ventilation may be used by occupants escaping.  Danger of released gases igniting higher portions of the building.

Types of Ventilation • Horizontal Ventilation: Open leeward side windows first at top. If windward side is opened first, may pressurize building upsetting the normal thermal layering. • Open windward side windows next at bottom. • Keep ventilation openings clear from obstructions. • Performed on floor(s) above fire floor. • Used mostly on multi-storied buildings. • When would you use horizontal vent on a ranch house? • Hint: (house has a basement)

•Horizontal –Open building on leeward side –Remove any obstructions –Open building on windward side –Remove any obstructions

Types of Ventilation • Vertical Ventilation: Opening made above the fire to relieve heat and gases due to mushrooming

Mushrooming: when heat, smoke & other gases accumulate To the state in which they bank down & begin to spread laterally To involve other parts of the structure. Caused by convection!!!

Types of Ventilation • Vertical Ventilation: Ventilation opening should be made directly over the fire and at the highest point.

Types of Ventilation • Vertical Ventilation: Utilize any natural openings already in place, such as: skylights, scuttle holes, exhaust fans, etc. These openings are faster to open than cutting a hole .

When attempting ventilation through a roof monitor, if the monitor is Not removable, 2 sides should be opened to create required draft.

Types of Ventilation ▫ Note the existence of obstructions or excessive weight on the roof.

Types of Ventilation • Vertical Ventilation: Ventilation openings should be large enough • (minimum of 4’ x 4’ ). *Kerf cuts are small cuts (normally the 4 ft

4 ft

width of the saw blade) sometimes Used to determine fire direction. *Inspection hole is done by cutting a Small triangle in the roof. *Louvered cuts are made in between the Rafters rather than beside the rafters Causing the panels to be hinged.

Square openings help facilitate roof repairs (Customer Service)

Types of Ventilation • Vertical Ventilation: Openings cut on pitched roofs should be on the leeward side and as high as possible. Wind

Observe wind direction in relation to exposure. Work with wind at your back or side.

Types of Ventilation • Vertical Ventilation: Make sure opening is clear from any material or obstruction. • Guard the opening to prevent personnel from falling into the building.

Last step in roof ventilation is to open up the ceiling below the Ventilation hole, with a pike pole or plaster hook. Be aware that excessive glass breakage including skylights, Explosions, additional openings between attack team & upper Opening, improper use of forced ventilation, & burn through roof Can destroy effectiveness of vertical ventilation.

Types of Ventilation • Trench Ventilation (strip ventilation): Used in buildings with large attic areas to stop horizontal spread of fire. • Identify escape routes. • Consider location, duration & extent of fire.

Good for venting small strip malls

Types of Ventilation • Trench or strip ▫ Advantages  Aids in stopping the horizontal spread of fire

▫ Disadvantages  Must be cut well ahead of the advancing fire  Must be a minimum of four foot wide and is timemanpower consuming

Types of Ventilation • Trench Ventilation: 4’ wide opening cut in roof from outside wall to outside wall.

Type of Ventilation • Trench Ventilation: Opening must be far enough away from fire to allow it to be completed before fire reaches there.

Type of Ventilation • Trench Ventilation: Tactic used to save rest of structure by cutting fire break in roof.

Type of Ventilation • Hydraulic Ventilation: Use of interior fog stream to move smoke and gases through window or door.

Pressurized ventilation

Type of Ventilation • Hydraulic

▫ Advantages

 May be used in situations other types are not  Takes advantage of the air drawn into the fog stream.

▫ Disadvantages    

May increase the amount of water damage inside the structure Drain on the available water supply Increase in the ice problem during freezing weather Firefighters operating the nozzle must remain in the heated, contaminated area  Remain aware of conditions around you; can intensify fire in surrounding area

 Operation may be interrupted when crew goes for fresh SCBA bottles

Type of Ventilation

• Hydraulic Ventilation: Wide fog pattern utilized approximately 2 ‘ from the opening.

2 ft.

Hydraulic Ventilatio n: Fog pattern must cover 85%-90% opening for maximum effect.

Type of Ventilation • Mechanical Ventilation ▫ Forced  Prevents smoke from churning in the opening.  Avoid blockage of the intake side of the ejector.

• Mechanical (forced) ▫ Advantages      

Ensures positive control Supplements natural ventilation Speeds the removal of contaminants Facilitates a more rapid rescue under safer conditions Reduces smoke damage Promotes good public relations

▫ Disadvantages  Introduction of air can cause the fire to intensify and spread  Dependent upon a power source  Requires special equipment

Type of Ventilation Negative Pressure: (Use of smoke ejectors)

• Placement of ejector for maximum effect (highest point in the opening and on leeward side of building if possible). • Place to exhaust is in same direction as the natural wind. • Keep airflow in as straight a line as possible

PROCEDURES • Mechanical/mechanical pressurization (forced ventilation) ▫ Negative pressure  Place ejector in opening to exhaust in the same way as the wind direction  Cover the area around the ejector to prevent churning  Establish and maintain desired draft path  Remove all obstacles  Avoid blockage of the intake side of the ejector

PROCEDURES ▫ Negative pressure  Place ejector in opening to exhaust in the same way as the wind direction.  Cover the area around the ejector to prevent churning  Establish and maintain desired draft path  Remove all obstacles  Avoid blockage of the intake side of the ejector

Type of Ventilation • Reduce “churning” (cover area around the fan with a salvage cover) • Remove items such as: drapes, blinds, screens, etc. which might block air flow. • Provide and maintain unobstructed replacement air opening. • Supplements natural ventilation • Speeds up removal of contaminants, assisting in creating a safer environment • Promotes good public relations

Type of Ventilation • Mechanical Ventilation:

Caution: Improper application of positive pressure ventilation may • Positive Pressure: (PPV Fans) increase fire spread and the safety hazards.

• Placement of PPV fan for maximum effect (outside – ground level on windward side of building). Placed a few feet outside the door. • Produce a cone of air to completely cover door opening. Have exit area same size as opening. • More efficient removal of smoke & heat.

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Type of Ventilation • Mechanical Ventilation:

• Positive Pressure: (PPV Fans) • Eject smoke from opening on opposite side of building (leeward side). • May pressurize one room at a time by closing interior doors. • Speed up process by reducing size of area being ventilated by systematically opening/closing doors. • A window screen could reduce effectiveness by as much as 50%. • Multiple story buildings point of entry is at the lowest point, point of exit is at highest point. • Do not block openings. • For greatest efficiency, exhaust opening should be 75% to 150% intake opening. • Equally effective with Vertical or Horizontal Ventilation. • Set without firefighters entering a smoke filled environment.

PROCEDURES ▫ Positive Pressure  Place blower several feet outside the point of entry  Check to make sure air cone completely covers the opening  Open the exit opening (75% to 150% of the entrance opening)  Systematically open and close doors within the structure to exhaust the products of combustion.

Type of Ventilation • Mechanical pressurization (positive pressure)  Cleaning and maintenance of blowers usually reduced.  System applicable to all types of structures.  Heat and smoke may be directed away from unburned areas or paths of exit

▫ Disadvantages    

May intensify and spread hidden fire. Gas power may increase CO2 levels in building. Noise affects communications. Control of openings and pressure leaks.

Caution: Prior to using PPV, firefighters must be property trained and aware that if used improperly, it can intensify and spread fire conditions. Refer to the PPV fan manufacturer;s training program.