Training Day: Ventilation basics
This simple firefighter training exercise will demonstrate the effects of flowing air when ventilating a structure fire
By Robert Avsec
Ask a group of firefighters to define the term ventilation and you’ll likely receive a variety of responses, based on their frame of reference – a product of their knowledge, skills and experience in conducting ventilation tasks on the fireground.
As a training officer, your challenge is to help your charges to develop a common frame of reference so that when ventilation tasks are communicated and assigned on the fireground, there is common understanding and not mass confusion (which endangers civilians and firefighters).
Tactical fire ventilation
Tactical ventilation encompasses those ventilation techniques necessary to make initial firefighting operations safer, more effective and more efficient. We call that the SEE Principle. Tactical ventilation goals should include:
- Controlling the flow path (how outside air is entering the structure and finding its way to the seat of the fire).
- Reducing the potential for flashover.
- Improving the tenability for trapped occupants (reducing heat and smoke conditions, particularly from the floor to a height of approximately four feet – the “survivability zone”).
- Improving operating conditions for firefighters.
Designing a firefighter training ventilation exercise
To conduct a ventilation training exercise, first start by finding a suitable structure in which firefighters can employ the required ventilation tasks (e.g., a two story, single-family dwelling, because single-family dwelling fires are the “bread and butter” type of fire for most fire departments). You want to develop the frame of reference in your firefighters for the type of fire they’re most commonly going to experience.
This can be anyone’s house, because all you’re going to be doing is opening and closing windows and doors, and flowing air into or out of the structure. The participating firefighters do not need to be wearing their full PPE ensemble or SCBA; helmets and gloves will be an appropriate level of protective equipment.
To enable firefighter visualization of the effects of airflow in the structure, a couple of rolls of painter’s tape will do quite nicely. Attach three-foot strips of tape at the top of all doors and inside each room from the ceiling. Also attach strips of tape on the bottom of all windows that can be raised so that the tape will be hanging down if the window is opened.
By setting up your “training structure” like this, your firefighters will be able to see what effect they have on airflow when they open and close doors and windows during the training exercise.
To create a seat of the fire, place a ventilation blower in one of the structure’s rooms with the airflow blowing out a window (this will simulate a fire that’s already vented the fire room and serve as the draw for the initial flow path).
Conducting the ventilation exercise
Start simple and expand as your personnel gain experience with the set-up. For the first couple of runs through the exercise, have all the interior and exterior doors closed; also have all windows closed except for one window in the fire room. Allow everyone to see how the initial flow path develops once the first exterior door is forced open.
Forcing entry must be thought of as ventilation as well. While forcing entry is necessary to fight the fire, it must also trigger the thought that air is being fed to the fire and the clock is ticking before either the fire gets extinguished or it grows until an untenable condition exists jeopardizing the safety of everyone in the structure.
Once the front door is opened, attention should be given to the flow through the front door. This rapid air movement through the front door is known as smoke tunneling. Smoke tunneling could indicate a ventilation-limited fire (a fire that still has plenty of fuel and only lacks the right amount of oxygen for free burning).
Every new ventilation opening provides a new flow path to the fire and vice versa, thus creating a potentially dangerous condition when there is a ventilation-limited fire. Demonstrate this effect by opening various exterior doors so that firefighters can see how the initial flow path is affected by observing how the suspended tape strips are moving.
During a vent-enter search operation, primary importance should be given to closing the door to the room. This eliminates the impact of the open vent and increases tenability for potential occupants and firefighters while the smoke ventilates from the now isolated room. The ventilation simulator you’ve created gives your firefighters the opportunity to see this effect as they open and close doors during a simulated primary search.
Keep firefighter training simple
Meaningful training does not have to be complicated. Safe, effective and efficient firefighting happens through the timely and correct execution of many individual tasks. By practicing each of those individual tasks (in this case, ventilation) to develop mastery, you’re creating greater potential for success when those individual tasks must come together in a fire suppression operation.