Ventilation increases survival chances
Assistant Division Chief–Training
Ottawa Fire Department
I read with interest the letter from George Cowan (March 1997) in which he states that “Class A foam has changed the need for or possibly even the priority of ventilation.” The Class A foam application described in his letter is essentially an indirect fog attack, which experience has shown should not be used where victims may be trapped or the spread of fire to uninvolved areas cannot be contained. Ventilation is still required in an occupied structure to reduce temperatures and remove smoke and gases that endanger trapped occupants. Proper ventilation increases the chances of survival not only for occupants but the firefighters performing the search.
While it appears that the addition of Class A foam to a fog stream will increase its effectiveness, it does not replace the need for an aggressive interior attack coupled with coordinated ventilation in structures where occupants may be trapped. The author`s statement “ventilate after the Class A foam attack to displace the white steam cloud if rescue is necessary” ignores the effect that the huge volumes of steam generated in the unventilated structure will have on the trapped occupants.
Class A foam has excellent potential as a supplement to our existing firefighting resources and procedures and should be viewed as such and not as a replacement for proven fire suppression practices.