Water remains the extinguishing agent of choice due to its abundance (most of the time) and extinguishing properties. The objective of fire departments is to move the water from its source to the base of the flames to overcome the British thermal units (BTUs) being generated. The real challenge to the fire departments and firefighters is to overcome the obstacles that can make this simple premise very difficult.
The location of the fire in proximity to the source of water, the complexity of the building where the fire is located, the building construction type, and the item or items on fire all affect the delivery of water to the base of the flames.
With the exception of wildfires and fires involving chemicals in containers, such as gasoline tankers, exterior fires are essentially open burns. While one could argue the potential danger of any fire and the need to be ever vigilant and avoid complacency, most of the time exterior fires do not place too much of a challenge on fire departments.
If left alone, exterior fires eventually would self-extinguish when they ran out of fuel. One could even argue that there is very little to save in these instances, with the exception of exposures. Vehicles are not rebuilt after a fire, and trash fires are just that, trash. But if the same fire were inside a structure, there are many things to consider. A car in a garage or trash in an apartment requires a little more effort to get the water to where it needs to be.
First and foremost the water needs to move from the source to the fire. The source can be a fire hydrant, tanker, or a natural or man-made source such as a pond or pool. The water usually needs to get from the source to the pump so it can be distributed to the hoses that will be used to get the water to the source of the fire. Water moves through a large diameter hose to provide the supply needed.
Fire departments have often decided that the bigger the hose, the better. Obviously if the diameter of the hose is larger, you can move more water. More water provides more options and the potential to supply more attack lines and master stream devices.
However, as with most decisions made by fire departments, consideration should be given to what options are available to address the hazards and fires most likely to be found. What does this mean?
Perhaps not every department needs the biggest hose it can get. Maybe the fire hazards most prevalent can be addressed with a smaller hose size to get the water from the source to the pump. A good hydrant system and multiple fire engines can deliver a lot of water. Smaller size hose is lighter and a little bit easier to maneuver.
Effects Of Staffing Levels
Depending upon your staffing levels, you may want to consider the advantages and disadvantages of the various sizes of large diameter hoses. Often it is not the size of the supply line that restricts the amount of water that can be flowed, but the number of firefighters available to staff the attack lines.
Now that you have the water to the pumps, you can work toward getting it to the fire. The pumps that you have are probably more than adequate. How many departments can honestly say that they use their vehicles to deliver 1,500 to 2,000 gpm?
Again, it is not the size of the pump that places restrictions, but the staffing levels. If you have only minimal staffing, you are not likely to require all the horsepower that your vehicle can deliver.
As with everything there are exceptions. If you need to deliver large volumes from deck guns, master stream devices or elevated streams, you can push your pump to capacity. The point of this is that fire departments need to look at what they most likely will be required to do and acquire the hoses and pumps that match closest.
Hand lines are used to move the water from the vehicle to the source of the fire and get it to the base of the flames if possible. The nozzle at the end of the hose will control the application of the water based upon its flow capacity, the pressure of the water being delivered, friction loss in the hose, and the hose stream selected. This is where the fire department, incident commander, and company officer need to select the best hose for the job to be done.
While physics tells us that the more water you apply the more BTUs you can absorb, there is a point where you become unable to practically apply larger volumes of water. If bigger were truly better all the time then we would have 5-inch attack lines. The combination of staffing (again) and the required maneuverability will tell you what size line you are capable of taking to the fire source.
While 2 1/2-inch line can deliver lots of water, it is very difficult to move once it is filled and charged. If you are not likely to have an abundance of firefighters available to move it, don’t use it unless it is to be placed in a static position. Also consider the need to turn the hose besides dragging it. The larger size hand lines do not take corners or stairs very well.
These lines can be used to get the water to the structure, but must be gated down to hose lines that are manageable by your personnel. You need to have hose that can be used based upon your staffing, the potential hazards to be faced and the types of structures most common in your community.
Training is the best way to determine what you and your department need. Do you have hydrants or will you rely on water shuttles? If it is hydrants, what is the spacing? What will your personnel be able to realistically do?
As for attack lines, you need to practice with all the lines that you carry and the nozzles that you use. Depending upon the demonstrated capabilities, your command and company officers can select the appropriate lines when they complete their size-up.
Each department needs to evaluate its own capabilities. Many departments do not frequently respond to working fires. This is good for the community, but does not allow for personnel to gain on-scene experience. Only through training and practice can they learn the lessons to allow them to make the right choices.
You need to determine how long it typically takes to establish the water supply to your engine and how many people it takes to do this. You need to know how long it takes to deploy your attack lines and how they will be advanced to get to the seat of the fire. Through a combination of training, education, and experience your personnel will know how they will meet up with the fire in the building and how much water they can deliver.
There are many products and many options. It is easiest to make the selection based upon what works for departments around you. But this may not be best for your department. Regardless, if you have a department, you have a method to get the water from the source to the fire. This is the basic premise of the fire service. Every department needs to be very good at doing this.
Your competence is a combination of the tools you carry to do the job and the ability of your personnel to use those tools. The tools need to not only match the potential hazards of your community, but also the capabilities of your firefighters. At this point it is about practice, practice, and more practice.
Editor’s Note: Richard Marinucci is chief of the Northville Township (Mich.) Fire Department. He retired as chief of the Farmington Hills (Mich.) Fire Department in 2008, a position he had held since 1984. He is a past president of the International Association of Fire Chiefs (IAFC) and past chairman of the Commission on Chief Fire Officer Designation. In 1999 he served as acting chief operating officer of the U.S. Fire Administration for seven months. He holds three bachelor’s degrees in fire science and administration and has taught extensively.