By Paul Shapiro
When we respond to a fire, we are expected to be able to extinguish it in a quick and efficient manner.
For the most part, I think the fire service has this down. Of course, nothing is perfect. Every once in a while, we experience unexpected problems that challenge us. One such challenge is a large-water-demanding fire that requires us to not only get enough water from water supplies to overwhelm the British thermal units (Btus) but also deliver or discharge the water onto the fire to get the knockdown as quickly as possible. This is where a lot of fires go bad.
We have all seen the big “super pumpers” that are used in refineries across the nation and all over the globe. These pumpers are designed to flow thousands of gallons per minute (gpm) to protect property (the oil) worth billions of dollars. These facilities are set up with water delivery systems that can support the flows that super pumpers are capable of. We are generally talking about flows in excess of 5,000 gpm. In fact, one available unit can flow 10,000 gpm when using a pressurized water delivery system.
There are also units with pumps rated at up to 3,000 gpm that can produce flows reaching close to the 5,000-gpm mark when used in the appropriate pressurized water delivery evolutions. Remember that pumps are rated at draft at 150 pounds per square inch (psi) net pressure. When a pressurized incoming water supply is used, it subtracts its incoming pressure from the overall pressure, thus allowing the pump to produce higher than rated flows. For example, a pump has a pump discharge pressure of 200 psi with an incoming pressure of 60 psi. By subtracting the 60 psi from the 200 psi, the net pressure will be 140 psi. With this being said, the pump has not maxed out its flow capacity capabilities because it has not reached the 150 psi net mark. It is possible to double the rated capacity of a pump under the right circumstances.
Can you imagine using these flows on some large fires that we get in the big city? We are talking about fully involved warehouse fires; construction fires; and, in general, fires that require thousands of gallons per minute to control and extinguish the fire as quickly as possible.
On the large fires described above, we currently set up our standard master streams and, if we max them out—which a lot of times we don’t—we are flowing basically 1,000 gpm each. Now you might say that if we’re flowing multiple 1,000-gpm streams, let’s say three, then we are flowing 3,000 gpm. So, why do we need a unit that can flow that much water? The problem is, yes we are flowing 3,000 gpm, but it’s over a widespread area. We are really only flowing three 1,000-gpm streams that only cover a portion of the fire, which, in many cases, is not enough water to knock it down.
Did you know that the big stream concept is not new? It’s just kind of faded away. If you research the municipal big stream concept, you can find information on some big cities in the United States that built apparatus that could flow more than 5,000 gpm and were very successful in controlling large fires.
So, why are we not using a super-pumper-style engine like this for municipal fire departments? There are probably several reasons. It is a specialty unit that would only be used on big fires and would be extremely expensive and may not see that big fire for years. So, we’re talking economics. Do we have a water delivery system that will flow 10,000 gpm to a single pumper? Yes, we do. Do we know how to move that kind of water to a specific location? Please don’t take offense, but most will not have the knowledge to do this.
Here are a few more reasons:
■ Change of administration and its agenda.
■ Fire departments having more work added to their plates such as emergency medical service, hazmat, swift water, etc.
■ Training failing to teach the importance of gpm vs. Btus.
■ Ignoronce. We all have 1,000-gpm deck guns. That should be enough. If we can’t stop it with that, then it’s unstoppable.
There are a couple of alternatives that can be done at a fraction of the cost. One is a pumper set up as a super pumper that can still be used as an everyday pumper running out of its own station in its own district, and you already own it. The other is a quick-attack unit, which is a pickup truck with a fixed master stream mounted to it that can be used as an everyday service truck to run the department’s deliveries to the stations.
Achieving the Flow
First let’s talk about the pumper. Based on the water delivery evolutions that will be described in Parts 1 and 2, a 1,250- or 1,500-gpm pump can provide 2,000 to 3,000 gpm with the correct equipment and supply line evolution. First you would need a master stream appliance that is designed with a four-inch (minimum) waterway and a four-inch discharge from the pump using a four-inch valve.
The Stang master stream, which is the one we used for these flow tests, operates best at a 100-psi nozzle pressure. Chart 1 lists the nozzle pressures and tip sizes for the smooth bore. These are only optimum—other nozzle pressures will work as you will notice throughout this section.
Notice that the nozzle pressures on this chart are above the 80-psi standard that we’ve always known and used with our master streams. The books tell us that 80 psi is the correct pressure when using smooth bore tips. As you can see, we’ve surpassed that number by quite a bit. A minimum of a 2,000-gpm master stream allows for a lot of combinations that will produce hard-hitting, high-flowing streams that, again, according to the books, were not possible. This operation is based on the manufacturer’s guidelines for the master stream appliance itself. Most manufacturers agree that the master stream appliance should have no more than 200 psi to the inlet of the appliance, with some requiring 150 psi to the inlet. The other requirement is the maximum allowed nozzle reaction for the appliance—the 1,250-gpm gun allows up to 631 pounds nozzle reaction while the 2,000-gpm gun allows 1,010 pounds nozzle reaction. A 3,000-gpm gun with a 100-psi nozzle pressure from a 3¼-inch tip has a nozzle reaction of 1,658 pounds. A good combination using the 2,000-gpm-plus gun is the use of a two-inch tip at 150-psi nozzle pressure. The flow achieved from this combination is 1,455 gpm with a stream reaching well over 200 feet in the working area of the stream itself. The nozzle reaction for this combination is well below 1,010 pounds, coming in at 942 pounds.
In my opinion, let the pros do the installation work for your super pumper project. Many apparatus refurbishing companies offer this. They are the ones that employ the professional designers and fabricators who know how to build the unit to counteract the high nozzle reaction that will occur from the high flows.
The type of water delivery operation needed to get the water to the super pumper is multiple relays. Up to five large-diameter hose (LDH) inlets could be needed, depending on the hydrant performance, the size of the hose, and the required flow. The intakes on the engines are used first because they are available and go directly to the pump. If the supply lines exceed the available intakes, then a manifold system needs to be used to receive them. If this is the situation, then one intake on the engine needs to be left available for the discharge of the manifold to connect to. If the valve is placed on the ground, a 20-foot section of five-inch hose connected from the appliance into the intake on the pump is needed. It’s important to lay the 20-foot section of five-inch at a 90-degree angle from the pump intake because when the relay lines are initially charged, they tend to push the manifold forward. At 90 degrees, a kink in the hose could be created but will be easy to straighten out. If the line is laid straight out from the pump intake, the valve and kink could be pushed under the pumper and will most likely be stuck and not able to be straightened out. This will severely affect the flow.
One thing we learned during our flow testing is that a manifold that is siamesed actually creates a lot of turbulence when the water merges inside, crashing into itself from each line. Using the type of manifold that Kochek provided on the supply side of the evolution made a difference. It’s basically a large tube with inlets/outlets going into it from both sides. This design, as well as placing the manifold on the supply side of the evolution, made a difference.
The four-inch gun can be used for standard flows as well as high flows. The engine of the apparatus does not have to be 600 horsepower, as with the industrial pumpers, because it is supported by the relay pumpers sharing the workload regarding engine revolutions per minute (rpm).
Fixed Master Stream Mounted on a Quick-Attack Unit
With the quick-attack unit, you have to be careful with the flows because of the lighter weight the truck possesses vs. a heavier fire truck. In researching the pickup truck capabilities, I found it difficult to get anything in writing as to how much nozzle reaction it could handle and still be safe. The truck I used is a 2005 Ford 250 extended cab that weighs 7,800 pounds. I talked with some quick-attack unit manufacturers and was encouraged by a major manufacturer that I could use it to flow 3,000 gpm with the proper installation. It recommended proper connection of the gun to the truck frame and outriggers to support the use of the gun off the side of the truck because of the potential high nozzle reaction. It continued to say that it now uses heavier trucks like the Ford 350 and 450 trucks when they want to push the 3,000-plus mark.
Again, in my opinion, let the pros do the installation work for your quick-attack unit project.
In Part 2, we will discuss setting up a pumper to be a super pumper, setting up a quick-attack unit, and setting up the operation for large-flow fires.
PAUL SHAPIRO is director of Fire Flow Technology. He is a nationally recognized instructor on large-flow water delivery. He is also a retired engineer from the Las Vegas (NV) Fire Department. He has authored numerous articles for fire trade magazines. He has been in the fire service since 1981, is author of Layin’ the Big Lines, and produced the first in a series of videos on large-flow water delivery.
Making Your Pumper a Super Pumper