Fire is the rapid oxidation of a combustible material, releasing heat, light, smoke, and various toxic gases

Transcription

1 VENTILATION

2 Fire is the rapid oxidation of a combustible material, releasing heat, light, smoke, and various toxic gases

3 If a fire is contained in a building, the heat, smoke, and toxic gases will spread. The air in the confined area can expand at a ratio of 3:1; pressurizing the building

4 Fire attack under these conditions can be extremely dangerous In addition, these conditions lower a victim s survivability profile.

5 If a free flow of air is introduced, fire attack and rescue can be performed more efficiently.

6 Ventilation is the planned and systematic removal of superheated air, smoke and toxic gases from a structure. VENTILATION

7 ADVANTAGES Aids in rescue operations Increases survivability potential of victims Improves visibility, reduces heat levels Decreases flashover and backdraft potential Aids in fire control Limits the spread of fire Property conservation

8 DISADVANTAGES If performed incorrectly, ventilation can actually accelerate the fire and increase the intensity and spread rate. Firefighters may be at risk performing certain operations on lightweight or un-reinforced construction.

9 TYPES OF VENTILATION Horizontal Natural Mechanical Hydraulic Vertical Combination

10 VENTILATION SIZE-UP Is there a need for ventilation? Where is it needed? Rescue vs. Suppression What type of ventilation? Structural conditions?

11 VENTILATION TECHNIQUES

12 HORIZONTAL VENTILATION Natural Mechanical Hydraulic

13 HORIZONTAL VENTILATION NATURAL

14 NATURAL VENTILATION Utilizes natural convection currents, 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)

15 NATURAL VENTILATION OPENING WINDOWS AND DOORS WILL PROVIDE NATURAL VENTILATION BY TAKING ADVANTAGE OF THE MOVEMENT OF AIR CURRENTS

16 HORIZONTAL VENTILATION MECHANICAL

17 MECHANICAL VENTILATION Positive pressure Fan positioned outside the structure Injects fresh air into the structure Negative pressure Fan positioned inside the structure Sucks heat and smoke out of the structure Combination

18 MECHANICAL VENTILATION POSITIVE PRESSURE (PPV) 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.

19 Blowers must be positioned so the cone of air issued from a blower will completely cover the entrance opening

20 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 degrees can improve operation)

21 Multiple blowers In-Line front blower 2 feet from opening, rear blower cones door. Larger blower in front smaller in rear Side-by by-side parallel blowers, less effective than in-line, but good for large openings

22 Sequential exhaust Multiple rooms each having their own exhaust opening. Effective ventilation requires controlling the exhaust openings with a sequential ventilation of the contaminated rooms. Each room should be handled individually one at a time.

23 Multistory PPV Multiple floors should be separately and individually ventilated.

24 Dead end room 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

25 Exhaust opening 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%

26 MECHANICAL VENTILATION 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

27 THREE KEYS TO EFFECTIVE HORIZONTAL VENTILATION Control the entrance opening Control the exhaust opening Control the path of travel between the two openings

28 HYDRAULIC VENTILATION 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

29 Hydraulic ventilation uses the air drawn into a fog stream to push the products of combustion out of a room or building

30 HYDRAULIC VENTILATION 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

31 HYDRAULIC VENTILATION DISADVANTAGES May be greater water damage to the structure Increased drain on the available water supply for firefighting tactics Additional nozzle time in superheated environment after knockdown for attack crew

32 VERTICAL VENTILATION

33 Climbing onto a roof when a fire is raging below is a high risk/low frequency event. Knowledge, awareness, and training are the keys

34 VERTICAL VENTILATION SIZE UP Building construction Occupancy type Ventilation for rescue or extinguishment Interior companies inside

35 Personnel VERTICAL VENTILATION PERSONNEL / TOOLS Residential: Minimum of 2 Commercial: Minimum of 3 Tools Sounding tool (pike pole, rubbish hook, etc.) Pick head axe Saw Communications PPE / SCBA (use it, just don t wear it!)

36 VERTICAL VENTILATION LADDER PLACEMENT Ladder 8 feet from the corners Ladder away from the fire Minimum 3-5 rungs above roof line Have a minimum of two ladders in position

37 LADDER THE STRONG CORNERS- DON T LADDER OVER STRUCTURAL OPENINGS

38 PLACE LADDERS 8 FEET FROM THE CORNERS

39 Plan Your Escape

40 Do Not Ladder Facade

41 Facade Collapse

42 VERTICAL VENTILATION TYPICAL FLAT ROOF PURLINS (8 o.c.) BEAMS (12-20 o.c.) RAFTERS (16 24 o.c.)

43 VERTICAL VENTILATION TYPICAL PITCH ROOF RIDGE BEAM RAFTERS (16 24 o.c.)

44 VERTICAL VENTILATION READING A ROOF Ventilators Do not remove, 30% more efficient if left intact Skylights Indicates purlin direction Good alternative for a heat hole HVAC Indicates beam location Vent pipes Growing pipes can indicate potential roof failure Pilasters Indicate beam location

45 Along with noticing ventilators and vent pipes, this roof has peaks and valleys that indicate the location of its structural members.

46

47 Indicators Sagging Roof Growing Vent Pipes

48 Exterior Pilasters

49 Interior Pilasters

50 Heat hole VERTICAL VENTILATION TERMINOLOGY A vertical opening in the roof to allow heat and smoke to exit Residential 4 x 4 Commercial 16 x 4 Louver A cut section of roof decking that is hinged vertically on a single rafter Rolling rafter When a structural member is encountered, the saw operator should lift the saw up and over the member without cutting into it. Trench/Strip Cut A long defensive type hole to stop the spread of fire laterally across the roof.

51 Dice Cut VERTICAL VENTILATION TERMINOLOGY Cuts made parallel and between rafters, mostly used on 1 x 6 sheathing Kerf Cut A small cut in the roofing composition to mark objects (usually used for rafters) Against Construction Cutting a ventilation hole while standing on a purlin (head cut perpendicular to the rafters) With Construction Cutting a ventilation hole while standing on a beam (head cut perpendicular to the purlins)

52 VERTICAL VENTILATION SOUNDING The structural integrity of the roof must be verified The rubbish hook is the best sounding tool Sounding tool should be the 1st tool on the roof Sounder should sound: Left,middle, right

53 VERTICAL VENTILATION PATH OF TRAVEL The strongest path of travel: Exterior walls Beams Purlins Rafters or cross country should always be avoided

54 VERTICAL VENTILATION DIAGNOSTICS Diagnostic methods Construction types Fire conditions Plug cut 45 Degree inspection hole Smoke indicator hole

55 VERTICAL VENTILATION PLUG CUT A plug is a triangular piece of composition that is removed from the roof covering only. Three small cuts with an axe or saw make a plug. The plug cut will reveal the type of roof decking that is underneath the composition covering as well as composition thickness. Because of remodeling or re-roofing, this cut may not always provide accurate information.

56 VERTICAL VENTILATION PLUG CUT A 3 x 3 triangle is made in the roof composition only. Cuts should be Overlapped by 4 on each side.

57 VERTICAL VENTILATION PLUG CUT The roof composition is removed to reveal the roof deck thickness and roof deck type.

58 VERTICAL VENTILATION 45 DEGREE INSPECTION HOLE A 45-degree inspection hole is cut through the roof decking to expose the construction of the roof underneath. Since construction is either parallel or 90 degrees to exterior walls, the hole is started by making a cut 45 degrees to any exterior wall. A 45 degree cut will ensure that the saw or axe will intersect a structural member.

59 Forty-five degree inspection hole A 45-degree inspection hole is cut through the roof decking to expose the construction of the roof underneath. Since construction is either parallel or 90 degrees to exterior walls, the hole is started by making a cut 45 degrees to any exterior wall. A 45 degree cut will ensure that the power saw or axe will intersect a structural member.

60 When the saw or axe contacts a structural member, roll it and continue about one foot past. To complete the triangular hole, make two additional cuts perpendicular to each of the exterior walls and remove the triangle. The hole should be cut away from the path of travel and may be cut smaller than your foot but larger than your hand. This allows structural members to be felt with the hand but minimizes the danger of someone stepping into the hole. The hole may be made larger if necessary. The hole should determine rafter direction, rafter spacing, type of roof decking and depth of cut.

61 45 Degree Inspection Cut

62 45 Degree Inspection Cut

63 Complete Triangle

64 Remove Plug

65 45 degree Inspection Hole

66 VERTICAL VENTILATION SMOKE INDICATOR HOLE A small triangular hole cut through the decking and insulation to indicate smoke and fire conditions in the structure. Place an indicator hole every 10 feet along the path of travel as well as at every change of direction. (Building size permitting) When placed in an area where personnel are working, the hole will give crews a good indication of changing conditions below them which is vital to a safe operation.

67 Sub-decking insulation is common and may need to be pushed through with the handle of a tool. If smoke is present, consider the color, pressure and temperature. Cold smoke would indicate that fire is not in the immediate area of the indicator hole. Hot black smoke (or fire) is an indicator of fire below you.

68 VERTICAL VENTILATION Offensive usually square or rectangular Defensive usually long and narrow

69 Heat Hole (Offensive) Strip Ventilation (Defensive)

70 VERTICAL VENTILATION NATURAL OPENINGS Roof scuttle covers, airshafts, skylights, elevator houses, and penthouse doors can be fast and efficient methods of ventilation. Make sure the feature used is in the right location in relation to the fire to avoid drawing the fire unnecessarily through the structure.

71 Skylights Use Skylights As You Would A Vent. Hole

72 Remove Glass

73

74

75 Roof Scuttle

76 Rotating Ventilators are 30% more efficient when the turbine is operational as compared to removing the turbine!!