Presentation on theme: "Ventilation Given information on ventilation the firefighter will be able to identify when and where to safely apply ventilation so that heat, smoke,"— Presentation transcript:
Ventilation Given information on ventilation the firefighter will be able to identify when and where to safely apply ventilation so that heat, smoke, and gases can be removed from a structure to improve conditions for fireground operations. This will be done to a written test accuracy of 75% and complete the practical evolutions in the allotted time to the instructors satisfaction. Goal
Ventilation Objectives The student will: Understand the importance of ventilation. Be able to identify when and where to ventilate. Understand the dangers of ventilation. Be able to identify the different types of roof construction.
Ventilation Objectives Cont Know the the different tools used for ventilation. Understand the compilations of ventilation Have an understanding of positive and negative pressure ventilation. Know how to explain and perform vertical ventilation.
Ventilation Objectives Cont Know how to explain and perform natural ventilation. Know how to explain and perform horizontal ventilation.
Ventilation Overview Importance of ventilation Different techniques Advantages and disadvantages Precautions and dangers Roof Types, and their construction Different types of ventilation Tools needed for ventilation
Ventilation The systematic removal and replacement of heated air, smoke, and gases from a structure with cooler air Ventilation
Advantages Rescue Increases survivability of trapped victims Improves visibility, and reduces heat levels Reduction of flashover and backdraft potential Fire attack Fire spread control Property Conservation
Ventilation Disadvantages or Improper Ventilation Fire spread Accelerated burning Puts firefighters in danger Triggers Backdraft Structural Integrity
Ventilation Dangers of ventilations Light weight construction. Can cause fire to intensify and spread. Places firefighters in danger. Backdrafts. Weather conditions.
Ventilation Complications Lack of Pre-planning Barred/Screen windows. Overhead obstructions. Access Weather Improper equipment Man power
Ventilation Ventilation Size-up Is there a need. (Why) Where is it needed. (Where) Type needed. (How) Structural conditions allow for safe operations. Timing (When)
Ventilation Coordinated Fire Attack Vent as close to the point of origin as possible coordinating with interior attack crew. Hose line ready and charged while firefighters are advancing. Ventilation of the fire room with outside vent person.
Primary Consideration RESCUE OR SUPPRESSION PRIORITY WITH INTERIOR ATTACK To keep smoke, heat, and gases away from victim. To reduce heat and Increase visibility For firefighters
Ventilation Types of Ventilation Natural Horizontal Vertical Mechanical
Ventilation Natural Ventilation – The means of ventilating a structure without the assistance of powered equipment.
Ventilation Natural Ventilation Wind. Currents created by the fire. Use Caution!!!
Ventilation Horizontal Ventilation – Is the venting of heat, smoke and gases through wall openings such as windows and doors.
Horizontal Ventilation Uses: Residential Multistoried structures Large unsupported open spaces.
Ventilation Vertical Ventilation Opening the roof or using existing roof opening to allow heated gases and smoke to escape.
Ventilation Roof openings Cut large opening –Minimum 4x4 –Windward side Smaller openings –May be necessary do to conditions Trench cut –From Exterior wall to exterior wall –4 wide
Ventilation Vertical Ventilation Uses: Attics Areas open to the roof
Mechanical Ventilation (Forced) – The means of ventilating a structure with the assistance of powered equipment. Positive-pressure ventilation (PPV), and Negative-pressure ventilation (NPV)
Positive-pressure ventilation (PPV) Induces fresh air into a confined area or structure resulting in an increase of pressure in that area which forces contaminated air through pre-selected and/or controlled openings Must coordinate with operation, and attack crews
Ventilation PPV Advantages Two times more effective than NPV Does not block doorways Does not expose personnel to contaminants while positioning blower Provides fresh air, reduces heat, and CARBON MONOXIDE during overhaul operations
Ventilation Disadvantages Noisy Not effective if there are to many openings Can cause fire spread, or ignite smoldering embers Raise CO levels with gas fans.
Ventilation PPV Fan Placement A single fan should be placed so the cone of pressurized air JUST covers the opening Tilting the fan back about degrees will enhance the operation Square box type fans can be stacked to achieve the same effect.( one fan on top of the other)
Ventilation Back far enough to seal the opening PATH EXHAUST Single unit operation Exhaust opening should b ¾s to twice the size of entrance
Ventilation YES! If you dont have standard PPV blowers on your apparatus, simply use NPV devices and stack them on top of each other, then reverse their positioning placing exhaust side in. - SMOKE EJECTORS -
Ventilation PPV Fan Placement Two fans one in front of the other (series, tandem, or in line) Front fan (Largest) about 2 feet from opening, and the back fan will be set back far enough to cover the opening with pressurized air Two or more fans side by side(parallel or dual) Fans should sit side by side and back far enough to cover the opening with pressurized air
Ventilation DISTANCE EXHAUST 2-3 feet Larger Fan Positive Pressure Series, tandem, or in-line Back far enough to seal the opening
Ventilation Parallel or dual
Ventilation Exhaust opening Most effective when the exhaust opening is three quarters to two times the size of the entrance opening. Varies do to size of the fan or the amount of fans operating. Optimum efficiency is easily obtained by a combination of training and practical experience.
Ventilation Determine PPV fan Size for a Given Structure Apply the PPV Rule of Thumb - Single family dwelling with up to 2,000 square feet: 18- to 21-inch fans - Ranchers and multistory dwellings up to 4,000 square feet: 24-inch fan - Larger structures (greater than 4,000 square feet) require multiple fan application with 2 to 3 24-inch fans - Always use multiple fans on high-rise structures 10 floors or greater
Ventilation Negative-pressure ventilation Draws contaminates from interior to the exterior causing a negative-pressure in the contaminated area allowing fresh air to enter from an outside source through another opening.
Ventilation Advantages Usually operates off of a 110 volt Usually explosion-proof motor
Ventilation Disadvantages Exposes personnel to the contaminated area Placement in doorways and windows require hangers, straps or other accessories to position them effectively Block entrances and hallways Contaminates are drawn through the fan causing additional cleanup and maintenance
Ventilation Mechanical Devices Gas Fan Electric Fan Mobile units HVAC systems Exhaust Systems Hose steams (Hydraulic)
Ventilation Gas Fans 2-cycle and 4-cycle engines 18 to 24 inch in diameter 3200 to 15,000 CFM Many different manufactures and styles Maintenance ( Gas, oil, and air filters ) Can cause CO levels to rise in structure
Ventilation Electric Fans Both PPV and NPV Require electric cords NPV fans sizes 16 to 24 inch, from 2 to 3 hp Square or circular encased, including motor PPV fans are 18 to 24 inch, from 3200 to 30,000 CFM
Ventilation Mobile ventilation units Diesel PTO Hydraulic 30,000 to 211,000 CFM
Ventilation HVAC Systems Some are designed to reverse to draw out contaminated air from buildings Maintenance personnel from building will provide that information If unsure Turn units off. Preplanning
Ventilation Exhaust Systems Some buildings have systems in place for other uses. Maintenance personnel from building will provide that information Preplanning
Ventilation Hose Stream (Hydraulic)
Ventilation Care and Maintenance PPV Blowers or Fans - Use proper oil and fuel mixtures - Keep belts tight and snug - Keep shroud(s) intact - Check fluid levels. Change fuel regularly and replace with fresh - Run blower - Keep rubber feet or base intact NPV Blowers or Fans - Clean blades and motor regularly - Keep electric cords and switches intact - Keep shroud(s) intact - Listen for any unusual noises during operation
Ventilation No properly trained crew When interior search or rescue teams or occupants are between the fire and exit point of smoke For well-involved attic fires with no egress venting When fire is present in the walls of balloon construction and no egress point is identified When backdraft conditions are evident. When the origin of fire is unknown. Too many openings in a structure preventing air flow from effectively pressurizing interior Contra indicators for PPV
Ventilation Ventilating multiple floors Pressurize stair shaft common to all floors Start with lower levels and work up Vent horizontally through exterior openings Vent to opposite stair shaft
Roof Construction Lightweight wood or metal joist Heavy steel trusses Wood I beams Built-up roof Concrete Roofs Metal roofs
Ventilation Lightweight wood or metal trusses Trusses in place of rafters Wood or metal decking Built-up roof Allows horizontal fire spread Fails after 5-10 minutes of fire exposure
Ventilation Heavy steel trusses Metal decking with built-up roof Starts to fail at 1000 degrees
Ventilation Wood I beams Substitute for lightweight trusses Contributes fuel to the fire Fails within 5 to 10 minutes of fire exposure
Ventilation Concrete roofs Precast concrete Lightweight concrete Reinforced concrete To vent this type is difficult and time consuming Use natural openings, skylights, scuttles, ventilators, stairwells
Ventilation Metal roofs Light-gauge steel Corrugated galvanized sheet metal Aluminum Vent with power saws using metal cutting blades, axe, or sheet metal cutters. Use natural openings
Ventilation Flat Roof Industrial, commercial, and apartment buildings Frequently pierced by chimneys, vent pipes, shafts, scuttles, and skylights May be surrounded and or divided by parapets May have HVAC unit on them
Ventilation Flat roof construction Wooden, metal, or concrete joist Wooden or metal decking Waterproof materials, insulation, gravel Reinforced, lightweight concrete, or precast concrete
Ventilation Built-up roof construction OR PLYWOOD GRAVEL
Ventilation Built-up Roof Opening built-up roof –Remove gravel if present –Make inspection cut –Cut insulation and composition down to decking –Remove materials, sound roof for rafters or bar joist, then cut decking and remove. –Be careful not to cut to deep to avoid causing structural damage to the rafters
Opening a flat roof Determining the location of the opening –Location and extent of fire –Wind direction –Exposures –Obstructions Open using the built-up roof method.
Ventilation Pitched Roofs Rafters or trusses 1X boards or plywood sheeting Felt paper Shingles- wood, asbestos, composition, metal, slate or terracotta tile. May be gypsum slabs, approximately 2 thick, laid between metal trusses.
Opening a pitched roof Determine the location of the opening same as flat roof Place roof ladder on the windward side of opening Locate the rafters Cut opening working the farthest distance from you towards yourself Remove the decking Push a tool into the hole to open a possible ceiling below
Opening an arched roof Cutting is the same as a pitched roof Use of a roof ladder would be unlikely Because of the potential for sudden collapse under fire conditions, roof operation should be done from an aerial ladder or tower.
Ventilation Hand tools Axe Halligan bar Pike poles Sledge hammer Can opener Hand saws Ladders
Ventilation Power tools Vent saws Chain saws Circle saws Reciprocating saws
Ventilation Power tool safety Proper maintenance Know tool operations and capabilities PPE Start tool before taking to operational area Never carry, hoist, or climb while running Keep front arm stiff while operating tools Work with a partner
Ventilation Review Discussed the importance of ventilation Discussed ventilation techniques Discussed the advantages and disadvantages of ventilation Discussed precautions and dangers of ventilation Discussed the different types of roofs, and their construction Discussed different types of ventilation Discussed the tools needed for ventilation