Entry and Ventilation

COURSE: FIREFIGHTER PRE-BASIC SESSION REFERENCE: 7 TOPIC: ENTRY AND VENTILATION TIME REQUIRED: THREE HOURS MATERIALS: ACQUIRED STRUCTURE OR FORCIBLE ENTRY PROPS, VARIOUS HAND AND POWER TOOLS REFERENCES: ESSENTIALS OF FIRE...


  3. Convected heat, smoke, and gases will rise within and around shafts

  4. If shafts are not vented at top, fire will travel horizontally

  5. Pressure will force heat, smoke, and gases throughout upper part of building

  6. Shafts are capped at roof with various closures (make sure of area being vented when cap is

      removed)

C. Cutting Through Roofs

  1. At times, only way to properly ventilate is cut hole in roof

      a. Roof made of boards can be cut with axe

      b. Roof made of plywood should be cut with power saw

      c. Care should be taken not to cut joists or other structural members

  2. Single large hole is more effective than several small holes

      a. One 4' X 8' hole has twice area of four 2' X 2' holes

      b. All roof boards should be cut through before any pulled up

      c. Keep back to wind when pulling boards

      d. When all boards ripped up, make opening in ceiling below

  3. Special care should be taken when fire is immediately below roof

      a. Open roof as close as possible to seat of fire

      b. If not, fire will be drawn across top of building to opening

      c. Hot spots may develop on roof

      d. If roof is flat, opening should be made at hot spot

      e. On gabled roof, opening should extend from hot spot to peak

      f. Draft can be increased by making an additional opening just above the eave line on side opposite

        original opening

       g. Care should be taken so that opening does not increase fire spread

D. Forced Ventilation

  1. Smoke ejectors

      a. Cannot be used as a substitute for natural venting techniques

          1) Fans should not be used in partially or completely confined spaces in which there is fire

          2) May be used in confined areas after fire has been knocked down

      b. Fan placement

          1) Most effective when placed where they tend to increase natural air flow

          2) When fans are positioned in windows or doorways, all shades, drapes, blinds, curtains, and

               screens should be removed

          3) If possible, open area around fan should be closed to increase fan efficiency by directing air

               through opening and preventing smoke from re-entering

           4) Be careful not to exhaust smoke into congested areas or into heating and cooling intakes

      c. Fans in tandem

           1) Can be especially effective when used in pairs

           2) Place one fan near an outside opening blowing smoke out and other inside room to blow

                smoke to first fan

           3) Fans can be used to exhaust smoke and draw in fresh air at same time

           4) Exhaust fan should be mounted high in vent opening

           5) Intake fan should be lower

  2. Positive pressure fans

      a. Introduction

          1) Fresh air introduced to increase pressure

          2) Selective process of opening and closing doors and windows - effective on all structures

              when doors and windows maintained

          3) Initiated outside structure

          4) Has potential of moving fire and fire gases

          5) Generally speaking, initiated between fire fighters and fire or between fire and trapped victims

          6) Can maintain primary and secondary egress routes

          7) Quicker than negative ventilation

          8) Works well in large areas

      b. Fan placement

          1) Place fan far enough away from door to fill opening with cone of air

          2) Stacking fans increases volume greatly

          3) For oversized doors, place fans side by side or in tandem

          4) For single fan, place 6 to 10' from doorway

          5) For multiple fans, place 3 to 5' from doorway

  3. Fog streams