Direct or Indirect Attack
By Lt. David Polikoff
Before we dive into this topic lets make sure we are on the same page. When I say indirect attack of a fire I mean the engine company is inside the fire building preparing to attack the fire in an offensive mode. By using the indirect attack method to extinguish the fire the nozzle man directs the stream at the ceiling and allows the water to rain down on the fire.
When I use the term direct attack I mean that engine company is inside the fire building preparing to attack the fire in an offensive mode. by using the direct attack method to extinguish the fire, the nozzle man directs the stream at the base of the fire.
Now that we are on the same page lets talk about each method of attack.
Indirect attack: The theory behind the indirect attack is to aim the stream of water ( 30 degree or less pattern) at the ceiling and allow the droplets of water to rain down on the fire. When this method is employed two things happen 1. the water cools the ceiling upsetting the thermal balance some of the water will vaporize into steam 2. the rest will fall like rain to the main body of fire below to extinguish the fire. There are things the the engine company officer must consider before using this type of attack. Are there any trapped occupants remember steam can kill a trapped occupant just as fast as smoke or fire. Steam can also burn us. Remember if you open the nozzle and it is on a pattern wider than 30 degrees you could be in for a world of hurt, especially if the fire has not vented. Remember the steam has to go some where. Lets go back to Firefighter I we all remember when the instructor told us to stand up in the fire so we could feel the heat and so we could also see the thermal layer. Well in a hot fire if you upset the thermal layer by rapidly cooling the ceiling you will drop the thermal layer down to where you are, that means you could be in for trouble.
There are times to use the indirect attack. If the fire has vented in the room of origin you will be able to push the heat and smoke and steam out the vent hole, because the fire products are exiting the vent hole you will reduce the risk of burn to you as well any trapped occupants. Another time that the indirect method will work for you is to control roll over or to cool the area ahead of you to prevent possible flashover. You are not putting the fire out you are cooling the gasses that could ignite behind you. Remember if you are moving towards the fire and the area gets hot do not hesitate to direct a straight stream at the ceiling ahead of you. In doing so you will reduce the risk of flashover.
Direct attack: The theory behind the direct attack is to put water directly on the base of the fire and not to disturb the thermal layer at the ceiling. This type of attack is best used with a straight tip nozzle or a straight stream( size depends on your departments policy on the minimum GPM to attack a fire) If the fire has not vented and you apply water to the base of the fire you will have rapid extinguishment of the fire and reduced steam thus reducing the risk of steam burns. The thermal layer will cool slowly and not drop down to where you or any trapped occupants are. Once the fire has been knocked use the stream of water to break out windows to relieve the remaining heat in the room of origin. In todays fires the smoke you will encounter will be thick and dark. There will be times you will not see the fire until you are right next to it. This can be a very dangerous situation firefighters can be burned if they get too close to the fire, this is due to the high BTU's that the fires of today produce. I have found that when you are in the room of origin and you can not see the fire, the best tactic is to open the nozzle and aim it about chest high 3 to 4 feet from the floor (chest high when you are on your knees) and sweep the room. This will ensure you will hit the base of the fire. Think about your typical living room or bedroom. Get on your knees and look. What is the highest piece of furniture? The bed or the couch. if you sweep the room at chest high you will hit the base of the fire. The rules still apply if you are making your way towards the fire and you encounter high heat conditions you can aim the stream of water at the ceiling ahead you and cool the area down, use short bursts of water and hit the 2 walls and the ceiling. Also use the nozzle to control roll over.
I know that some will not agree with my tactics and that's fine. I can only tell you what I have used and what I have found that has worked. The goal is to go home the same way we walked into the fire house.