(Don’t) Let it Rain: The Effective use of Low-Level Master Streams
One thing that drives me nuts and one of my many pet-peeves is seeing the tower ladder or stick, 75-100’ in the air raining down water on a defensive fire. I will prepare you, this will be of little tactics but mostly rant. Defensive operations are not fun and the traditional approach of throwing the aerial 100’ in the air with our fog nozzle on the end and let it rain, doesn’t work! How have we not figured this out yet?
A roof is meant to keep water out, hence, the only purpose for existing. When a fire breaks through the roof, the pyrolysis has weakened the structural components of the roof and fire is venting from that hole. Typically, this is the only vent of the structure vertically, allowing all the smoke/ fire, and superheated gases to exit and on well-involved structures, exit with velocity. This creates a thermal column rising straight up.
Our tactics, try to throw water into the superheated column of smoke and fire to extinguish the fire. Possible, not probable, or least effective. Looking back at thermal properties, as we discussed in the last article “Smooth or Fog: the Debate that Really Isn’t”, When water flows through superheated gases, the water will steam convert before hitting burning material, and since in these operations it’s not in a compartment, it has no effect. The water can also be carried away by thermal current or wind, not having any effect on fire conditions. Lastly, the water could hit the roof and run to the ground, as it’s supposed to.
These issues are magnified when equipping the master stream device with a fog nozzle. As we know, Fog nozzles create smaller droplets of water which are more easily converted to steam because of the volume of the droplets. The steam has little to no effect because of the superheated column which the fire has created. These smaller droplets are also more prone to be carried away because of the uprising of the thermal current and due to atmospheric wind.
Smoothbores on mater stream devices are not only a necessity but a requirement. When faced with a defensive operation, the smoothbore master stream allows for greater penetration and more punch with the solid column of water hitting the surface. Also, the thermal impact of the heat on the larger droplets of water will not be as significant. This makes penetration through the thermal column and on to burning material more possible.
In some instances, we have to attack the fire a little higher than from below, if we are faced with a situation where the roof materials have become the source of the fire, then we need to attack the fire from angles, not from above. Placing the master stream on a plane with the fire will give you access to the fire and allow the stream to hit the burning material without having the degradation effects of the thermal heat. If the roof is opened a majority of the building footprint, attacking more overhead is acceptable but try to lower the stream to prevent air currents from disrupting the fire stream.
TACTICS
First, Smoothbore on your master stream devices!
Secondly, the Tower Ladders and Ladder Towers offer the biggest asset on the defensive fire ground, if we know how to use it. To avoid water through the thermal column, we need to get water from below. We can do so by placing the waterway at a plane or below access points to get water up and in. This includes windows, storefronts, and overhead garage doors. WATER FROM BELOW WINS DEFENSIVE FIRES.
Third, Punch the fire in the face with the biggest weapon we have! I hate when the tips of the master streams are never removed. Volume wins and we need to be cognizant of what we are putting into the building. A 1 3/8” puts 500-700 gpm whereas a 2” flows 1000 to 1500gpm depending on the pressure you are pumping. What’s going to make the biggest difference? PUNCH IT IN THE FACE!
By placing the master stream below grade or below the fire compartment, we are able to use many different advantages than when raining water from above.
We are able to get water to the seat of the fire, at the fuel-flame interface (Shoutout AF), which allows for cooling of the material and fire extinguishment.
We are able to direct the heavy stream up and in to bounce the stream off the ceiling and be an internal sprinkler head flowing 1000gpm or able to hydraulically overhaul by penetrating the drywall or interior material to access the hidden fire. In addition, we can also use the extreme reach of the master stream to reach the back of strip malls or larger buildings.
The tower ladder/ Ladder Tower allows for extreme maneuverability of the fire stream. Having a 1000+gpm stream that is extremely maneuverable is a significant advantage to access different parts of the building or multiple compartment/ units of strip malls. FDNY is the master of these operations. Low-level master stream at the sidewalk, high angle fire stream.
Fire Streams are at or below the fire location. Photo Kurt Von Dietsch
Photo from Fire Engineering