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VENTILATION

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  1. VENTILATION

  2. Objectives 1 of 3 • Understand ventilation as a fire service tool. • Know the principles, advantages, and effects of ventilation. • Know the origins and effects of heat, smoke, and toxic gases. • Differentiate between flashover, backdraft, and rollover.

  3. Objectives 3 of 3 • Identify safety considerations when venting operations are in progress. • Identify the factors affecting ventilation. • Describe ventilation techniques. • Identify the types of ventilation. • Identify the mechanics of ventilation.

  4. Introduction • Ventilation is the planned and systematic removal of pressure, heat, gases, and smoke. • Ventilation is a very complex subject area with many factors. • Ventilation is a part of thecoordinated fire attack. • Ventilation will be in place before fire attack!!

  5. Principles, Advantages, and Effect of Ventilation 1 of 3 • Ventilation is the relief of the products of combustion from an enclosed area. • This is a very essential part of fire suppression effort. • This prevents fire from heating up other parts of the structure.

  6. Principles, Advantages, and Effect of Ventilation 2 of 3 • As heat is exhausted and dissipated its ability to spread the fire is reduced • Ventilation channels smoke out of the structure. • As smoke builds up vision is obscured. • Heavy smoke conditions can obscure light completely.

  7. Principles, Advantages, and Effect of Ventilation 3 of 3 • Unburned hydrocarbons irritate eyes. • Smokes contain many deadly substances. • Removal of smoke will add survival time to a victim, increasing the chance of successful rescue.

  8. Heat, Smoke, and Toxic Gases • When fire burns, air heats, expands, becomes lighter, and rises. • Heated air spreads by convection and radiation. • Fire gases consists of many deadly products of combustion. • Newer approach to construction makes ventilation even more important.

  9. Considerations for Proper Ventilation 1 of 3 • Important to understand behavior of fire gases. • Smoke rises and mushrooms. • Vertical ventilation is the removal of gases and smoke through vertical channels. • Horizontal ventilation is channel smoke through horizontal openings. • Without ventilation, heat, smoke and steam have no where to go.

  10. Path of Travel for Smoke

  11. Considerations for Proper Ventilation 2 of 3 • An opening is needed for smoke and by-products to exit as attack team moves in. • Ventilation can be as critical as applying water. • Many factors must be considered when venting.

  12. Considerations for Proper Ventilation 3 of 3 • A size up of the structure is very important. • Height of building will also have an impact. • Wind can alter ventilation. • Bad weather affects smoke’s ability to travel. • Through proper ventilation the fire’s ability to extend can be removed.

  13. Fire and Its By-Products • During combustion energy is released. • Molecules reunite to form new substances. • These substances can be caustic to humans. • Ventilation will remove some substances. • Ventilation has many other benefits. • Flashover, backdraft, and rollover can occur without ventilation.

  14. Fire Phenomena • Flashover. • Backdraft (smoke explosion). • Rollover.

  15. Flashover • Light, smoke, and heat are liberated as part of the combustion process. • Everything in a confined area ignites at almost the same time. • It is important to know the mechanics of a flashover to understand its development.

  16. Backdraft (Smoke Explosion) 1 of 2 • A rapid ignition of smoke. • Incomplete combustion occurs as oxygen levels decrease. • As fire consumes greater amounts of oxygen, the production of CO increases. • With the heat, pressure builds in the confined space.

  17. Backdraft (Smoke Explosion) 2 of 2 • When an opening occurs, a billow of smoke escapes. • Cooler air causes air to contract. • Mixture increases CO concentration. • Once CO concentration reaches the flame, components are primed for ignition.

  18. Signs of Potential Backdraft • Smoke-stained windows. • Puffing of smoke at seams and cracks. • Smoke pushing out under pressure. • No visible flames. • Heavy black smoke. • Tightly sealed building. • Large, open area or void. • Extreme heat.

  19. Rollover • Heated products of combustion rise to higher levels. • Heated gases reach their ignition and begin to spread across the room along the ceiling. • When the upper thermal layer is disrupted, the heat is forced down.

  20. Expanding Heat and Steam

  21. What Needs to be Vented? • Without ventilation expanding heated steam and smoke will roll over. • Small voids and compartments need to exhaust increasing pressure. • Areas such as cockloft need to be checked. • Horizontal and vertical voids.

  22. Areas to Vent

  23. Mechanics of Ventilation • Ventilation is simply the movement of air from high pressure to lower pressure. • Knowing the natural tendency of air movement is important. • Improvement of air conditions is crucial. • Horizontal and vertical ventilation conform to the same rules.

  24. Mechanics of Ventilation • SYSTEMATIC removal of products of combustion. • Ventilation controlled fire.

  25. Ventilation controlled fire

  26. Break glass. Open doors. Rope and a tool. Hook or pike pole. Iron or Halligan. Ax. Portable ladder. Aerial ladder tip. Negative pressure. Positive pressure. Ventilation Techniques

  27. Types of Ventilation • Ventilation can occur using several methods: • Natural. • Mechanical: • HVAC. • Smoke fans. • Positive pressure. • Hydraulic.

  28. Ventilation

  29. Vertical Ventilation

  30. Vertical Ventilation • Objectives: • Describe all safety concerns with vertical ventilation • Describe advantages and disadvantages of vertical ventilation • Describe common procedures for vertical ventilation • Demonstrate ability to determine roof integrity • Identify proper tools used during vertical ventilation

  31. Vertical Ventilation • This next section will cover Vertical Ventilation, both on Residential and Commercial Buildings • We will cover the basics on how to ventilate these types of buildings • There are several types of material that is used for the roof decking • We will start out with the Residential Roofs

  32. Vertical Ventilation • Residential Roofs • These types of roofs can be either flat or pitched • The procedure is fairly simple • Whether the roof is pitched or not, the procedure is the same

  33. Vertical Ventilation • Vertical Ventilation Tools • Cutting • Pick head or flat head axe • K12 Circular Saw (All Engine Companies) • Chain Saw (T82) • Stripping • Pike Pole • Rubbish Hook (T82)

  34. Vertical Ventilation • Existing Roof Openings • Scuttle Hatches • Commercial Occupancies • Skylights • Residential and Commercial • Air Handlers • Residential and Commercial • Exhaust Vents • Commercial • Attic Vents

  35. Vertical Ventilation • Safety Concerns • One of the most dangerous jobs on the fire scene • Use of power tools • Visibility • Smoke/Heat • Full PPE • Access/Egress • Multiple points • Roof Integrity • SOUND IT!!, SOUND IT!!, SOUND IT!!

  36. Vertical Ventilation • Accessing the Roof • Minimum on 2 access/egress points • Place on different walls of building • Ground or Aerial Ladders • Aerial Placement • Interior roof access • Scuttles

  37. Vertical Ventilation • Size Up the Roof • Construction type and features • Ridge Line/Truss Direction • Weight Bearing Walls • Lightweight Construction • Age of Building/Roof • Loads on Roofs • Drop Offs • Existing Openings • Skylights, Scuttles, etc

  38. Vertical Ventilation

  39. Vertical Ventilation • Size Up • Roof Covering • Tile vs. Shingles • Torch Down • Metal • Synthetic Foam Membrane • Signs of Integrity • Sagging Roof lines • Vents growing • Fire Smoke Venting

  40. Vertical Ventilation • Getting on the Roof • Sound the Roof • Before you step on the roof • Strike the roof with a tool (axe, rubbish hook) • Feel and sound solid • Regularly sound the path you choose and stick to the sounded path. • Scan the roof continuously

  41. Vertical Ventilation • Working on the Roof • NEVER cross roof diagonally • Walk on ridges, trusses, outside walls • Work from roof ladders if possible • Work from aerials if possible • Consider safety hoseline (controversial)

  42. Vertical Ventilation • Open the Roof • BE SAFE ALWAYS • Never cut in line with your body or that of your partner • Work in teams of two minimum • One person cuts, the other backs him up • If you fall and begin to slide, flatten out and your partner will jump on you

  43. Vertical Ventilation • Open the Roof • Inspection Holes • Helps find direction of trusses • Triangle in shape • 1-2 foot per side

  44. Vertical Ventilation • ALWAYS work on the WINDWARD • (Wind at your back) • Don’t get caught down wind – that is where the fire is going

  45. Vertical Ventilation • Louver Opening • Fast and Efficient = less time on roof • Must know direction of trusses/rafters • NEVER stand on the hole you are cutting • Always work back to your egress

  46. Vertical Ventilation • The goal is to get a hole at least 4’ x 8’ • It can be cut in line with the trusses or perpendicular to the trusses • If the cut is made perpendicular to the trusses, you have to cross at least three trusses. Three on the top and three on the bottom • If the cut is made in line with the trusses, you will only have to cross the truss once at the top and one at the bottom

  47. Vertical Ventilation • Louver Opening 1st Cut Mark Trusses 2nd Cut 3rd Cut 4th Cut Last Cut

  48. Ventilation Cuts

  49. Vertical Ventilation • After the hole is cut • Open the ceiling • Contact Command • GET OFF THE ROOF!!

  50. Trench cut • Trench Opening • Typically used in commercial • Long, narrow opening • Assist in stopping the fire spread • Long time to accomplish = long time on roof • Can also be louvered