By: Joe Boyle
So what are the considerations regarding operations using booster water?
How much water do I have?
How long will it last?
How much fire can we extinguish?
We may also seek answers to some tactical questions such as:
How aggressive an attack can be mounted?
Should we try to conserve water?
What are our communication considerations?
The purpose of this article is to provide an analysis to those questions.
In the urban environment – with a well established water delivery system, and a network of fire hydrants – establishing a quick and constant high-volume supply of water is rarely a problem’ however, it may not be so quick. While for the most part it is true that urban areas usually have water supply grids and hydrants at regularly spaced intervals, the key word in that statement is “quick.” Even junior members come to realize in short order that many problems arise when an engine company is trying to establish their water supply while getting the first handline into place.
Hydrants can be, and often are in some areas, blocked by parked vehicles. Poorly maintained hydrants may have stripped threads or may not operate at all. They may also be filled with litter or debris which can clog pump intakes. In cold weather climates, hydrants that do not drain properly can freeze or may be buried in snow. When these or other unforeseen problems are encountered, an engine company must rely on the water that is carried in the booster tank for the initial handline.
A good engine company must have confidence to operate on booster water. When an order is sent to charge the handline, the pump operator should immediately drop any other tasks (such as hooking up to a hydrant) and supply booster water. The reason for this is simple: a life may immediately hang in the balance and charging the line with booster water is an order, not a request. The pump operator can immediately return to securing hydrant water once the line is charged with adequate pressure. Communications here is crucial to a successful operation. The hose team must be made aware that they will be on booster water. Just as important are communications to other incoming units if any problems are encountered with establishing hydrant water.
Once an engine is pumping, it is committed to that location. If a problem is encountered with the original hydrant of choice, the pump operator will almost surely need some help. This may mean calling for another member from another incoming unit to help, or it might require the service of an entire company to relay water using large diameter hose from a more remote hydrant. In all cases, the pump operator must remain calm, focused and communicate clearly with concise messages to the hose team and other incoming units of what the problem is, and what form of assistance is required.
Assuming that an engine is going to be operating on booster water, the answer to the question of how much water do we have and how long it will last is something that all members should know, and have an innate practical feel for. In order to meet National Fire Protection Association (NFPA) 1901: 5.4 guidelines, pumping apparatus must have a minimum of a 300 gallon water tank. The vast majority of pumping apparatus in urban areas usually have tanks that hold between 500 – 1000 gallons. Let’s assume for analysis that the booster is 500 gallons.
The next question is what size hose are we going to use. Again, for analysis, we will use 1 ¾ “ hose with a flow of 180 gallons per minute (gpm) using a smooth bore nozzle with about 50 pounds per square inch (psi) at the nozzle. An automatic combination nozzle may flow 200 gpm or more depending on nozzle specifications. Keep in mind that these nozzles may require 100 psi at the nozzle to produce such flow rate, and result in greater nozzle reaction. When confronted with the higher reactions, nozzle firefighters often gate down at the nozzle for better control. Unless flow meters are used, it is often difficult to establish an accurate flow rate using automatic nozzles.
A 180 gpm nozzle will flow will last for 2 min and 46 seconds if all 500 gallons are available. In reality however, the whole 500 gallons are not available. Consider, for example, the water volume needed to fill the hose and the water left in the tank and pump.
So how significant is this water volume and does it affect our operation time?
To calculate the water volume in the hose, we can apply the mathematical formula for the volume of a cylinder and apply that to the hose diameter and length. Without losing your interest to mathematics, the rounded off results are 6 gallons per 50ft 1 ¾” hose and 13 gallons per 50ft 2 ½” hose. So how long will the stretch be? In urban areas where private dwellings prevail and engine companies use an inline supply from a hydrant, a 200 foot stretch may be the most common. A 200 foot stretch of 1 ¾” hose means there is up to 24 gallons of water in the hose. In urban areas where walk up apartment buildings are common and engine companies use a back stretch to a hydrant, it is not uncommon to see stretches of 6 lengths of 1 ¾” hose filled out with another 5 lengths or more of 2 ½” hose for a fire on a top floor. With these stretches, we are looking at a more significant 100 gallons of water in the hose!
It is also possible that there may be water left in the tank that does not reach the pump. Such may be the case if the pumper were parked on an incline. It seems, however, when compared with the water in the hose on a long stretch, that this amount is probably negligible when factoring operation time.
Using the scenario of operating a line at 180 gpm, a long stretch, and 500 gallons, our operation time has fallen to 2 min and 13 seconds. In my mind, this length of time of continuous operation is still “a lot of time” and it is worth drilling on to get a real world practical feel for it. Even if it still “feels like” a lot of time, how much fire can we extinguish with that line? Is it possible to actually calculate how large a body of fire can be handled with our booster water based on the heat vaporization properties of the water we have available.
There have been a number of studies conducted which aim to give some idea of water requirements to extinguish structural fires. According to chapter 6 of Fire Service Hydraulics and Water Supply by Michael A Wieder, three formulas commonly used by the fire service in the last fifty years are presented and explained. They are: The Iowa State Formula, the National Fire Academy Formula and the Insurance Services Office Formula. After analyzing these formulae, it becomes clear that they are aimed at providing estimates for fire flows necessary to develop preplans rather than to provide for tactics at working fires1. What’s more, these results are only approximations of fire flow requirements at best.
The NFPA Fire Protection Handbook 20th addition sums it up as follows:
Currently no broadly accepted methods exist for prediction of energy release rates based solely on basic measurements of material properties. In addition, in any enclosure fire, the actual rate of heat release is dependent not just on the burning fuel but also on the fire environment, i.e. enclosure geometry and ventilation, the manner in which the fuel is volatized, the efficiency of the vapor combustion and other physical and chemical effects2.
All this is technical jargon states is that there is no sure way to predict the amount of heat produced at a structural fire whether it is one room or numerous rooms that are involved.
So where does that leave us in determining how far our hoseline flowing booster water will go in putting out fire? It can be summedup with one word: experience. I have always found it fascinating how little water it sometimes takes to extinguish a fire when it is applied directly to the burning fuel. A room of fire in a residence is quickly knocked down in seconds when the nozzle is positioned at the entrance or inside the room itself. I remember one such fire as a probie where, dare I say, that I was disappointed at how quickly the fire was knocked down. Conversely, I have had the experience where the line was open for a considerable amount of time just to extinguish a one room fire.
In that case, the line had to advance through a very large apartment in practically zero visibility just to reach the burning room. Flames could be scene in the heavy smoke even as the line advanced, but the fire was not being knocked down. This of course was a classic case of not actually getting water on the fire. The fire in the room was sending flames and high heat into the hall. Although the line had a cooling effect and afforded some protection as the line moved in, the main body of fire could only be extinguished as the final turn was made into the fire room. Needless to say, there is also the scenario where more than one room is involved and the line will need to operate longer.
All of your experience must come into consideration, as well as general size up measures when making a decision on how aggressive your attack can be using only booster water. The life hazard is always the primary consideration. When a known life hazard exists, we need to be as aggressive as possible. When performing a size up, it is very important that we try get a good idea of the size of the area involved in the fire. Companies operating on the perimeter of the building should report and relay what they observe to those on the inside.
We must also be aware of the risks to members associated with a seemingly routine operation. Running out of water without a knockdown of the fire can have, in certain situations, devastating results. One of the more dangerous scenarios is advancing down a long narrow hall to get to a burning room. The nozzle team may find it necessary to keep the line open for protection down this hall. If they were to run out of water with fire extending out of a room, they might find themselves in a very dangerous position.
Gusts of wind through vented windows, or sudden flashovers in adjacent rooms, will create extreme heat in that hallway very quickly. In the ensuing high heat, the nozzle team may find in necessary to open the line fully in order to protect them and their exit.
As always, the pump operator has a critical role in informing the nozzle team of how much water is left at various intervals, and when hydrant water is finally obtained. The most common benchmarks are at half and a quarter tank of water remaining. The pump operator must get confirmation from the engine officer that these vital messages have been received. Members operating in the fire area such as a search teams, must also process this information and conduct their searches accordingly. Without proper knowledge, a search team may think that fire knockdown is imminent, and may unknowingly put them in an overly dangerous position if water runs out.
The question may also arise as to whether to try to conserve water while operating the line. Without getting too technical, the general theory of fire extinguishment holds that it is not only how much water is applied, but more importantly the rate at which it is applied. The more water we can apply in a shorter amount of time, the better our chances of getting a knockdown.
As a rule, I would say that if we can put ourselves in a position with the nozzle where we can effectively reach the main body of fire, conservation of water should not be a consideration. If however, the line cannot hit the main body of fire, and instead is being used for defensive purposes or for protection of a position until hydrant water is obtained, a more conservative use of water should be considered.
Ideally, all handlines should have a constant source of water, but in reality, it’s only a matter of time before an operation using booster water alone will arise; that event will test the limits and judgment of the engine officer and firefighters involved. With some forethought, drilling and preplanning, engine companies will be better prepared and have added confidence to effectively handle these situations.
1. Weider, Michael A. (2004). Fire service hydraulics and water supply. Fire Protection Publications: Stillwater, OK.
2. National Fire Protection Association. (2008). Fire protection handbook 20th edition. NFPA: Quincy, MA.
