Fire Service Ventilation (7th Edition)-All Chapter Numbers



Fire Service Ventilation (7th Edition)

Chapter 1-Fire Behavior & Airflow Characteristics

"By The Numbers"

▪ Flame temperature in the incipient phase can be above 1,000oF.

▪ Room temperature early in the incipient phase is about 100oF.

▪ Oxygen content during the incipient phase is about 20%.

▪ During the steady-state phase, temperatures in the upper regions can exceed 1,300oF.

▪ Oxygen content during the hot-smoldering phase is about 15% or LESS.

▪ During the smoldering phase, temperatures are well over 1,000oF.

▪ Carbon monoxide combines with hemoglobin in the blood 200 times more readily than oxygen, causing hypoxia.

▪ Carbon Monoxide has a flammable range of 12.5% to 74% and an autoignition temperature of 1,128oF.

▪ Some departments require a Carbon Monoxide reading of 50ppm or lower before personnel can work inside a space without SCBA.

▪ Night inversions can yield a temperature difference as much as 25oF in 250 vertical feet.

▪ Chlorine gas is 2 1/2 times heavier than air.

▪ Methane has a specific gravity of 0.554.

▪ Hydrogen has a specific gravity of 0.069.

▪ Acetylene has a specific gravity of 0.906.

Fire Service Ventilation (7th Edition)

Chapter 2-Ventilation Size-Up

"By The Numbers"

There are no numbers of relevance in this chapter.

Fire Service Ventilation (7th Edition)

Chapter 3-Horizontal Ventilation

"By The Numbers"

▪ Walls have studs commonly spaced on 12 to 24 inch centers.

▪ Exterior masonry walls usually range from 8 to 12 inches thick.

▪ Veneer-over-frame walls are usually made from 2x4 or 2x6 inch structural members (studs).

▪ Foam veneer may be in blocks or sheets ranging from a few inches to 1 foot thick.

▪ Single-acting doors swing at least 90 degrees in one direction only.

▪ Double-acting doors swing 180 degrees from the frame in both directions.

▪ Fire doors have a 4 inch vent hole in the center of the door. (figure 3.42)

▪ Winds of up to 25 mph may be overcome by blower(s) depending on the size and efficiency during positive-pressure ventilation.

▪ When ventilation with a fog nozzle, it should be kept at a 60 degree fog spray and cover 85% to 90% of the opening.

▪ Compared to mechanical smoke ejectors, fog streams are capable of removing 2 to 4 times more smoke.

Fire Service Ventilation (7th Edition)

Chapter 4-Vertical Ventilation

"By The Numbers"

▪ A clear space of at least 10 feet should be observed in all directions of personnel using cutting equipment.

▪ Burning bars operate by a torch feeding oxygen and up to 200 amperes of electrical power to an exothermic cutting bar that produce temperatures in excess of 10,000oF.

▪ Cutting bars range in size from 1/4 to 3/8 inch in diameter and from 22 to 36 inches in length.

▪ A roof that slopes 5 inches for each foot horizontally from the ridge is said to be a "five-in-twelve" roof.

▪ A roof that slopes 12 inches for each foot horizontally from the ridge , a twelve-in-twelve roof, is the same as a 45 degree angle.

▪ Ridge rafters on gable roofs are usually 2x6 inches or larger and are spaced at 16 to 24 inch on center.

▪ In hip roof construction, hip rafters run at a 45 degree angle from the ridge beam, down and beyond the walls at the corners.

▪ In bridge truss roofs, when constructed of wood, trusses are usually made from 2x12 inch lumber.  Joists are usually 2x6 or 2x8 inch and are covered with 1x6 inch sheathing.

▪ In sawtooth roofs, rafters are usually 2x8 inches or larger and use wood or metal supports for bracing.

▪ The growing use of 2x4 inch trusses with gusset plates and 1/2 or 3/8 inch plywood decking can present great hazards to firefighters.

▪ Many fire departments have their dispatchers announce (over the radio), the elapsed time of an incident at 5, 10, 15, and 20 minutes.

▪ Flat roofs usually have a "two-in-twelve" pitch to permit drainage.

▪ In inverted roofs, the main roof joists are set at the level of the ceiling and a framework of 2x4 inch members is constructed above the main joists.

▪ Wooden deck roofs commonly use lightweight 3/8 to 5/8 inch plywood decking which offers little fire resistance.

▪ It is difficult to cut concrete roofs that are over 4 inches in thickness.

▪ Poured gypsum roofs are usually covered with a layer of gypsum cement up to 2 1/2 inches thick to which mesh reinforcement is added.

▪ At least 2 sides of roof monitors should be removed.

▪ Ribbed arch roofs are usually constructed of 2x12 inch or larger wooden members.

▪ The chords of arch members in bowstring arch roofs are usually laminated 2x12 inch or larger lumber.  Rafters are usually 2x10 inches and are covered by 1x6 inch sheathing.

▪ Lamella roof framework usually consists 2x12 inch wooden members bolted together at intersections with steel gusset plates and covered by 1x6 inch planking covered with composition roofing material.

▪ In modern construction, heavy timber, laminated beams, and 1x6 inch sheathing have given way to 2x4 inch lumber and 1/2 inch plywood.

▪ Panelized roof construction consists of laminated beams of various sizes (commonly 6x36 inch) that span the length or width of the building.

▪ Beams in panelized roofs may be bolted together to form lengths in excess of 100 feet and be spaced from 12 to 20 feet apart.

▪ Wooden purlins in panelized roofs (usually 4x12 inches) with metal hangers are installed on 8 foot centers between and perpendicular to the beams.

▪ Wooden joists in panelized roofs (usually 2 inches by 4 inches by 8 feet) are installed with metal hangers on 2 foot centers between and perpendicular to the purlins.

▪ In panelized roofs, sheets of 1/2 inch plywood (4x8 feet) are nailed to the wooden joists.

▪ In open web trusses, steel tube members are made from 1 to 2 inch cold-rolled steel tubing with ends pressed flat into a semi-circular shape and a hole punched through each end.

▪ In open web trusses, spans of up to 70 feet are attainable using a single 2x4 inch or two 2x3 inch members as the top and bottom chords.

▪ In open web trusses,  joining 2x4 inch lumber with mitered and glued finger joints, a continuous member of 20 feet or more is possible.

▪ Normal spacing of joists in open web truss construction is 2 feet on center.

▪ Metal gusset plate truss construction usually consists of 2x4 inch lumber held together by gusset plates.

▪ Gusset plates with 3/8 inch prongs are most common.

▪ Spans of up to 55 feet are possible using 2x4 inch lumber and gusset plates.

▪ The most common spacing for metal gusset plate truss construction is 2 foot on center and usually covered with 1/2 inch plywood sheathing.

▪ Wooden I beams consist of a top chord, bottom chord, and a 3/8 inch plywood or chipboard stem.

▪ Wooden I beam chords are usually made from 2x4 inch lumber, however, 2x3 inch lumber may also be used.

▪ Common spacing for wooden I beams is 2 foot on center.

▪ Shingles or shakes are usually nailed to wooden 1x4 inch or 1x6 inch planked sheathing with a spacing of about 1 inch.

▪ Rolls of composition shingles are most commonly found in 36 inch widths.

▪ One form of urethane/isocyanate foam is 4x8 foot sheets of foam insulation.

▪ Lightweight metal roof coverings are usually 18 to 20 gauge steel panels set over a wood or metal substructure.

▪ Steel clad roofs either consist of 1/4 inch thick by 2 inch wide strips laid at right angles to form a "grid" which leaves small openings from 6 to 8 inches square, or 4x8 foot sheets of steel, ranging from 1/8 to 1/4 inch thick welded together to form a continuous layer of steel.

▪ A 1/4 inch steel plate weighs about 10 pounds per square foot.

▪ Roof covering may be cut with a chain saw or rotary saw (depending on type of roof) at a 45 degree angle to any exterior wall.  The blade will usually encounter a rafter before the cut is 3 feet long.

▪ If rafter direction cannot be determined, cut a small 8 to 10 inch triangular cut at the known rafter location to determine direction.

▪ One 8x8 foot ventilation hole is equal to four 4x4 foot holes.

▪ When cutting parallel to rafters, the hole will be approximately 4 feet wide and 4 or more feet long.

▪ Trench cuts are made approximately 4 feet wide across the entire width of a building.

Fire Service Ventilation (7th Edition)

Chapter 5-Forced Ventilation

"By The Numbers"

▪ Smoke ejector sizes are based on fan size and range from 16 to 24 inches.

▪ Blowers which are usually larger (18 to 36 inch) and have greater rated capacities (LESS than 5,000cfm to MORE than 16,000cfm).

▪ Vehicle-mounted blowers are found in sizes from 48 to 72 inches in diameter and are capable of producing from 80,000cfm to over 200,000cfm.

▪ NFPA 92A, Recommended Practice for Smoke Control Systems.

▪ NFPA 92B, Guide for Smoke Management Systems in Malls, Atria, and Large Areas.

▪ When using negative-pressure ventilation, fan discharge should be centered in an opening and effectively cover 80% to 90% of the opening.

▪ When using positive-pressure ventilation, the blower(s) should be set up 6 to 8 feet outside the entrance opening.  The exit opening should be 75% to 150% of the entrance opening.

▪ When using fans of unequal size, the larger fan should be placed about 2 feet from the entry opening to provide the pressurization and the other a few feet further back to provide the seal.

▪ A blower set up properly at ground level can force smoke out of rooms more than 20 floors above.

▪ Optimum position for smoke ejectors is inside the space to be ventilated, about 6 feet back from the exit opening and placed anywhere from floor level to 4 feet above floor level depending on whether contaminants to be ejected are heavier or lighter than air.

▪ A fog stream set at 30 to 60 degrees and covering 85% to 90% of the exit opening is found to have the best results.

▪ When using a master stream device to hydraulically ventilate, it must not be increase beyond 60 degrees or it will lose its air-moving efficiency.

Fire Service Ventilation (7th Edition)

Chapter 6-High-Rise Structures & Special Situations

"By The Numbers"

▪ Relief crews in high-rise fires should be set up (staged) 2 floors below the fire floor.

▪ Staffing on high-rise incidents may be 4 to 6 times as great as a smaller structure.

▪ NFPA 204M, Guide for Smoke and Heat Venting.

▪ Curtain boards generally extend a distance to at least 20% of the vertical distance from floor to roof but not lower than 10 feet above the floor.

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