Firefighting Principles and Practices
1974
In this statement from a highly regarded firefighting text, Chief Clark encapsulates the critical role that ventilation plays in fire attack. As we discussed in our previous article Random Thoughts on Ventilation, there is a significant misunderstanding in our department regarding the true place and value of proper ventilation tactics, and a dangerous underestimation of the destructive power of poor ventilation. The key issue is the failure to recognize the significant difference between true fireground ventilation, and the loss control tactic known as smoke removal; unfortunately, the term “ventilation” is often used to describe both operations, leading to many dangerous misconceptions. Ventilation has a significant, direct effect on the growth, spread, and subsequent extinguishment of a developing fire in a building; smoke removal is a salvage tactic designed to reduce the amount of damage in a building, and to return the building to a habitable state. Because the goal of each operation is vastly different, the considerations and strategies for each must reflect these differences.
One of the primary reasons for performing ventilation at a building fire is to improve the chances for victim survival. At its most simple and fundamental definition, ventilation is designed to release dangerous smoke and heat conditions, so as to improve the atmosphere where the victims are located. If we are to actually accomplish this goal, we cannot approach this ventilation scenario in the same way we approach a “food on the stove” smoke condition; the margin for error will be much slimmer, and the consequences of improper actions much more harmful. We may be able to wander around an apartment building, arbitrarily opening and closing windows and doors until the smoke from the burnt food is gone; however, when a growing and spreading fire endangers life, our operations must be well-timed, coordinated, and, most of all, correct for the situation.
There are some basic, non-negotiable principles of fire growth that must be considered each time ventilation is performed. As most of us know, a fire within a building will be limited in its growth and spread by the availability of fuel, heat, and oxygen. When fire involves a structure, particularly a modern energy-efficient building, the growth of the fire is often restricted by a relative lack of fresh air from the outside. This inherent factor can serve to benefit firefighting operations by slowing the spread of fire throughout the building, but can also have negative effects, such as delayed flashover and the build-up of extreme smoke conditions. Understanding these potential effects, members performing ventilation must carefully consider the action they are taking and the effects that action will have on the fire.
“For Fire”
As a rule, it is important to hold off on making horizontal ventilation openings in a fire building until we are capable of controlling the spread of fire; more often than not, the “landmark” for this action is the point at which the attack line is charged and in a position to attack the fire. At that point, the windows on the opposite side of the fire from the attack line are vented, allowing the smoke, heat, and steam associated with the fire attack to be forced outside the building and away from the operating members. Once the fire is controlled, horizontal openings can be made at will, with the goal being to create as clear a condition on the interior as possible. These tactics are commonly referred to as “for fire ventilation.” The fundamental principle behind this strategy is that without outside air, the fire will remain relatively stifled in its growth and spread. Smoke conditions can be extreme and high temperatures can exist in the fire area, but the ability of the fire to grow is restricted.
“For Life”
Although “for fire ventilation” is a solid strategy for keeping the fire in check, and then releasing it as water is about to be applied, it can have other adverse effects on our overall operations. Because the smoke and fire gases are contained within the building by the lack of ventilation, trapped occupants will succumb quickly if they are not removed by searching members. Additionally, the reduced visibility within the building will make the search slower and less effective than in a relatively clear atmosphere. It is for these reasons that a strategy known as “for life ventilation” is employed in situations where a life hazard is known or suspected to exist. The premise behind this strategy is that we are trading off the dangers associated with premature ventilation for the potential ability to locate and remove trapped occupants while there is still a chance for survival. It should go without saying that employing this strategy can be extremely dangerous to victims and operating members alike, and that careful consideration and evaluation of conditions must be the rule.
“For Life” Considerations
If the decision is made to perform “for life” ventilation, it is important to ensure that critical fireground factors are considered before openings are made. Many of us mistakenly believe that simply because a victim is trapped, it is acceptable to break every window in the building. All of the potential hazards that make us wait to break windows in a “for fire” situation still exist when a victim is trapped; inappropriate openings can not only doom the victim, but may also endanger the unprotected members performing the search. The only way we can improve conditions for the victim, while keeping the risk level relatively low is to select the right windows to break at the right time.
Unless a significant exterior wind condition exists, the act of breaking a window will normally draw the fire in the direction of that window. As the new air supply feeds the growing fire, the fire will also move toward that air supply as it grows. For this reason, a “for life” vent opening should be made in the fire room itself; this will relieve the condition in distant areas, as well as drawing the fire away from the victim’s location. In addition to this opening designed to “control” the fire, it is also necessary to improve the conditions in the area of the victim. The best way to effect this change is obviously to break a window in the area where the victim is located (provided that we can identify that area.) Unfortunately, the same fire behavior traits that we try to exploit with the window in the fire room, may now draw the fire toward the victim we are trying to get to. Because of this potential danger, searching crews must work quickly and also make a few additional moves to reduce the risk of the now growing fire.
Door Control
Although we may not be able to decide how the fire grows and spreads once we make our “for life” openings, there are some simple steps we can take to protect ourselves and the victim. Most simple and most critical is the control of interior doors in the fire building. The quick closing of interior doors will help to contain the spreading fire and will also serve to protect victims and searching members. The two key doors to control are the one separating the fire room from the rest of the building, and the one to the room containing the victim.
Closing the door to the fire room should be a key part of every fire suppression effort, particularly those that involve “for life” ventilation. Shutting off the fire from the rest of the building, and then ventilating the fire room can be an effective control technique; in “for life” situations it can provide just enough protection to pull off a difficult operation. In addition to containing the fire, we have to isolate the room containing the victim. By closing the door to the victim’s room, we can protect ourselves as we operate and allow the venting of that room’s window to clear conditions without drawing the fire toward us. This tactic should be used anytime a room is searched above or ahead of the fire, but is especially critical when attack lines are not in place.
Vertical Ventilation “For Life”
Because it acts to release fire conditions differently than horizontal ventilation, vertical ventilation will greatly benefit trapped victims in most situations. By releasing smoke and fire gases at the highest points of the building, the mushrooming and lateral spread of fire can be greatly reduced. It is critical that the vertical openings are made in the proper spots, or the reduction of lateral spread can be ineffective. Roof cuts or natural openings directly over the fire room or directly over stairways can allow searching members a quicker and safer operation, and may allow trapped victims more time to escape, or to be located and removed. As with horizontal openings, it is very important to control interior doors in conjunction with vertical ventilation. Containing the fire in its present location, while opening the roof above is often more effective at stopping fire spread than simply breaking the window in that room.
Closing Points
Although on paper “for life” operations appear simple, the sheer unpredictability of the growing fire makes them very dangerous. A thorough understanding of fire behavior and adequate initial and on-going size-ups are absolutely required to make the correct decisions for a given situation. The techniques described in this paper assume that we know two key pieces of information: the location of the fire, and the location of the victim. If either of these factors is unknown, decisions will be much more difficult. If extraordinary conditions exist, such as strong winds or heavy fire loading in the building, we may be better off delaying ventilation until the line is in place; the damage we could do by venting in these situations may outweigh the potential benefits to the victim.
Some of us mistakenly believe that opening windows as we search is always a good thing; many of us were taught at an early age that any window we encounter in our travels must be immediately opened. Each of us must understand that although it may be hot, dark, and uncomfortable in an unventilated area, the random opening of windows will not necessarily improve those conditions. Even if breaking a window makes it more tenable in the short term, we must remember that without controlling the fire, interior temperatures will soon increase and overall conditions will soon be worse than when we started.
The calculated risk associated with early venting has to be undertaken after a proper assessment and understanding, rather than simply a thoughtless response to a potential life hazard. The benefits of ventilation must always be weighed against the damage that ventilation can possibly cause; no scenario requires this risk/benefit analysis more than “for life” ventilation.