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 TM 55-1915-200-SDC
Section XIV. SMOKE CLEARANCE
6-24. INTRODUCTION. As smoke is secondary in nature to fire, it should be considered by the fire fighter in combating
the fire. The primary objective must be to extinguish the fire and when that has been accomplished completely, then
steps should be taken to remove the smoke and fumes that remain. Although smoke and fumes must be considered
hazardous to the breathing of personnel, the hazard can be completely avoided by the use of oxygen-breathing
apparatus. The reduction in visibility by smoke is a hazard as well as a nuisance which must be endured until the fire has
been completely extinguished.
This procedure differs radically from that practiced ashore where ventilation is used to rid a building of accumulated
heat and smoke, making access easier for rescue and fire fighting. Since a single ventilation system aboard ship
frequently serves a number of compartments, premature use might result in spreading a fire beyond established
boundaries. This is further discussed in the following paragraphs.
Fire that occurs in the open on weather decks does not present such a serious smoke problem, as this type of fire
can normally be combatted from the windward side, the smoke being carried away by air currents. The problems
confronted by the fire fighter in combating a fire in a below-deck space are more difficult because of the presence of
smoke and fumes. The fire fighter's objective must be to extinguish the fire despite other difficulties.
Generally, there are no effective means for combating smoke or fumes during the progress of an interior fire. In
most instances, ventilation should not be attempted during the progress of a fire in an effort to improve visibility. The
known additional fire hazard resulting from the use of ventilating systems or ducts during a fire is considered of greater
importance than the doubtful improvement in visibility resulting from their use. To conform with fire fighting procedure as
explained in this chapter, all ventilating system closures, both supply and exhaust, are secured in the area where a fire
exists. Not only should ventilating system closures be secured, but electrical systems to blowers and similar devices
should be deenergized also.
Open ventilating ducts, particularly in vertical systems, will act as vents for the fire, thereby prolonging the life of the
fire and contributing to the difficulty of bringing the fire under control. In addition to the introduction of air (oxygen) to the
existing fire, there is always the hazard of spreading the fire by combustion of dust and other debris which collects in
ventilating systems as the result of infrequent or improper cleaning.
Ventilating ducts which remain open to a compartment in which there is a fire can quite easily become the vehicle for
spreading fire and fumes to areas of the ship which otherwise would be unaffected. Combustible gasses or fumes
passing a sparking motor may easily explode, causing further damage and possibly additional fires. The foregoing is
6-25
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