PROVOCATIVE QUESTIONS

PROVOCATIVE QUESTIONS

RANDOM THOUGHTS ON…

1. VERTICAL VENTILATION of an occupied structure can USUALLY be done promptly and without orders on arrival. What are those occasions when it can or should be delayed?

At high-rise residence buildings. Fires in these tight oven-like structures rarely extend beyond the occupancy (apartment). The life-safety strategy in this heavily occupied structure is to put the fire out. Rapid movement of the extinguishment and support functions depends almost solely on effective and immediate horizontal ventilation. Primary ventilation, in this case, is the exterior venting of the fire apartment windows. This can be accomplished by aerial device if the apartment is within reach or from the apartment directly above. Vertical ventilation is a secondary consideration, especially when responding personnel is limited in number.

When flammable or explosive vapors that are heavier than air are confined within a structure. Gathering at lower levels, they may be too rich to burn on our arrival. The ventilation assist, in this case, is horizontal, not vertical. Vertical venting will allow air to EN TER the occupancy and dilute the vapors down into the explosive range.

Peak roof venting by routine. If the fire is not in the attic this tactic becomes a risky, timeand personnelwasting evolution, especially if available personnel are minimal and the private dwelling is occupied with people waiting for us to find them.

Even if the cut is made in the proper place —high and parallel to the ridge rafter—how do you complete the vent channel from the fire to the outside air? Trying to push the ceiling down from this position in most private dwellings is extremely frustrating. Beneath is storage, on heavy sheathing material, of everything from Christmas ornaments to cribs and mattresses of their nowadult children. Life safety (search and rescue) is our first priority in these structures, and vertical venting should be put on hold until that life is accounted for AND additional personnel who can be spared for that function are available.

2. What are the chances that an unknown flammable gas within a structure is lighter (vertical venting) or heavier (horizontal venting) than air? What’s vour guess? Can there be a rule of thumb to guide us? You bet!

It’s important for every firefighter to know that there are only 9 lighter-thanair gases that we may encounter. All the rest are heavier than or equal to the weight of air. Remember those nine and you w ill always be ahead of the game:

Hydrogen, ammonia, helium (inert), acety lene, methane, illuminating (natural) gas, nitrogen (inert), carbon monoxide, and ethylene form the memory acronym HA HA MINCE.

3. There was one favorite question on old promotion exams and it is still a basic guide to size-up and fireground action. What do you do first: rescue life, confine the fire, locate the fire, extinguish the fire, or protect property? When this question is asked in many seminars or other assemblies of fire service responders, the overwhelming answer is rescue life. Of course!

Wrong! There is no sure way to account for human life effectively without first knowing where the fire is. There have been many cases in which firefighters (I was one of them) have placed ladders at buildings adjacent to the fire structure because of smoke conditions and of firefighters using all resources to rescue civilians visible at the front of the building and making the most noise, only to lose civilians who were more seriously exposed at other locations.

When manpower is minimal and visible life-exposures are many, how do you know which of the “screamers” are most severely exposed? Which have the least time?

At large-area multiple dwellings, are you sure the civilians at the front windows are in danger at all? Or are the most severely exposed at shaft or rear windows? What I’m saying is that our commitment of personnel and equipment to serve the rescue function must follow our ability to assess quickly the probable location of the fire within the structure—only then should we use our superhuman efforts to rescue first those we know must be in the most danger.

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