When we open the entry door, we’ve been told to think of that as ventilation, and the effects of that action as negative. The fire service should never think of entry in a negative context. We should think about entry as creating flow.
Flow is more than just air going to a fire or moving away from it. Flow gives us the opportunity to evaluate conditions on the inside once the door opens. Interpreting flow direction and function from this location provides an opportunity to determine if we are in a shared or single directional space.
Is the opening providing a bi-directional flow? Bi-directional flow Is low-air entry and high-level exhaust within the same opening. Is the opening displaying a uni-directional flow? Uni-directional flow is an opening where a single direction flow is prominent. A location with a uni-directional flow can function as an inlet flow or an exhaust flow.
Is the open entry door a ventilation point? Of course it is, but it’s more than that. It’s an information portal. When you open the entry door, heat and smoke will escape and fresh air will also track in low. This new flow will find its way to the fire. The route it takes is the flow path. It may return to you or exit in another area depending on its function. Understanding directional flow tells our people a lot more than simply saying something is ventilation.
Opening the entry door is required for us to size up the fire, enter and provide extinguishment. When we open the entry door, we can also close it. When you remove glass, we can’t control that opening any longer; however, doors are different, we can control doors there by controlling flow.
Firefighters know that air will feed the fire, and that fresh air will track inside low to the ground. That entry air can be beneficial to someone lying on the floor in the path to the fire – the flows path. Flow is what we’re interested in understanding, flow towards the fire and away from the fire. If you were to enter through the doorway and close the door behind you, you have eliminated that flow.
By discussing the term Flow, we bring understanding to the movement of air, gases and fire. Firefighters need to understand that the creation of flow is not a negative, and the controlling power they have over flow. While we can’t always control flow we must consider it’s path as we operate and avoid being in an active exhaust flow. There shouldn’t be negative connotations to opening an entry door. There should be understanding of actions and the impact of those actions, so that recognition is more universal.