Reading Interior Conditions
After the smoke and/or environment is evaluated prior to entering a structure, it is mandatory for personnel engaged in interior operations to constantly monitor the environment for changes until the fire is extinguished, extension has also been extinguished, and ventilation operations have removed the contaminants. Reading interior smoke should focus on the three basic considerations of the initial company, later arriving companies, and unvented attic fires as follows:
INITIAL COMPANY
The initial company on-scene to a structure fire is confronted with numerous considerations, three of which are interior conditions, logistical priorities, and time for the support.
First, what are the conditions upon arrival, and what priorities (or operations) will be necessary to provide support for suppression operations? It is difficult to prioritize necessary support operations unless the extent of the problem is initially evaluated.
Secondly, with all of the responsibilities that comprise support operations, priorities can be simplified if they are categorized into primary and secondary operations. Primary responsibilities are most often comprised of forcible entry/exit, ventilation, search, and ladders (these four operations are necessary to ensure that attack operations are timely and successful). Secondary support responsibilities include operations necessary to back up complete primary support functions, utilities, additional ladders, salvage, and so on.
Third, how much time will be required to perform primary support responsibilities and will additional companies or personnel be required for completion? Remember that if additional companies or personnel are required, it will be necessary to evaluate how much time it will take for those resources to become engaged in suppression operations. There is a significant difference between several minutes and ten to fifteen minutes!
LATER ARRIVING COMPANY
Later arriving companies are also confronted with numerous considerations, three of which are conditions, priorities, and time. First, what are the conditions from the perspective of progress or a lack of progress? As an example, if the second arriving company (or personnel assigned to logistical operations) finds the incident is winding down and initial priorities have been or are being completed, then secondary considerations should be evaluated. However, if suppression efforts seem to not be satisfactory, then the priority shifts to supporting or augmenting these operations.
Secondly, logistical support can be evaluated from the perspective of primary or supportive operations. As previously mentioned, primary logistical operations are in most cases ventilation, forcible entry/exit, and search. Have these three priorities been addressed? If not, how can the additional company address the most important priority?
If primary logistical support has been addressed, then the focus should be secondary support. Secondary support operations consist of additional ladders, utilities, operations necessary to augment primary logistical operations, etc.
Lastly, the amount of time required to complete logistical operations must be evaluated. This also includes the amount of time necessary for additional resources to arrive on-scene to augment complete fireground operations.
UNVENTED ATTIC FIRES
Unvented attic fires are confined in an attic area and are not vented to the exterior of the attic. Although these fires are frequently easily recognized, they present several noteworthy hazards that must be carefully evaluated:
As a result of a high fire load (ceiling joists, rafters, etc) and a lack of early detection, these fires can be well advanced in a short period of time. As a consequence, the lack of ventilation will result in a rapid and significant buildup of heat which will be radiated in two directions - up and down. The downward radiation of heat will raise the interior temperature of the structure that is nearest the ceiling, and can enhance the potential for a flashover without advance warning condition.
If personnel pull the ceiling to provide an opening for attack operations into the attic space, the opening can also become an exhaust vent for the expanding steam which can be a dangerous condition for attack personnel.
In Figure 1, arriving companies found a vacant single story SFD with conditions as pictured. Notice the pressurized smoke from the eaves and that the doorway only shows smoke at the top. Most importantly, notice the hot, pressurized, black roiling smoke from the attic vent. This is a clear indicator that there is an advanced unvented fire in the attic which has made interior conditions extremely dangerous.
Unvented attic fires can be best suppressed by either vertical ventilation or by using piercing nozzles. Vertical ventilation will vent the heat, fire gases and smoke vertically out of the attic, thereby allowing a hose stream to be directed from below.
A piercing nozzle can be deployed through the ceiling (which leaves the ceiling intact and provides a barrier between personnel and the fire) and uses the resultant steam to suppress the confined fire with minimal danger to suppression personnel.