For as long as people have been making fire, they have been using water to put it out. From bucket brigades to horsedrawn steamers and now modern computer-controlled electric pumpers, water has been moved from a source to the fire.
It does not matter whether it is a wildland or a structural fire—the concept is the same. Our job as firefighters is to efficiently transport the water from a source to the fire and apply that water. Modern pumpers can deliver 2,000 gallons per minute (gpm) with ease. Do we have a source that can deliver that much water to the fire scene? I intend to take this question and make it a point of conversation and training for fire departments.
Let’s take a brief look at what has changed with fires. Legacy construction used wood, wool, or fiberglass insulation; copper pipes; and furniture made from natural materials. The times from ignition to flashover were 12 to 20 minutes. Current construction practices use more synthetic materials for insulation, PVC pipes, and petroleum-based foams for furniture that reach flashover in a few minutes. Delivering the water quickly and efficiently is more important than ever.
Apparatus
The apparatus we use come in all shapes and sizes. There are custom-built apparatus where we can specify everything or a stock chassis and basic pumping apparatus. The function remains the same though: put water on the fire. It is how much water we hope to move that can be specified on different apparatus. Class A pumps range from 1,000 to 2,500 gpm. Which apparatus gets ordered is determined by the needs of the buying entity. We know that industries may need a high volume of water while residential areas can employ the standard 1,500-gpm pump. Communities that have limited water supply locations, either hydrants or cisterns, may require long hoselays. Communities with tight streets or older water supply infrastructure also may require apparatus to carry larger amounts of supply hose. These requirements can adversely affect the amount of tank water that can be transported by the apparatus. The reliance of moving water to supplement the onboard water can be critical to a successful outcome.
Large-Diameter Hose (Ldh)
Typical supply line diameters are 4 inches and 5 inches. Anything more than that becomes unmanageable for firefighting personnel. A 6-inch empty hose requires numerous personnel to handle and becomes almost impossibleto move when filled with water. Departments that use 5-inch supply hose are doing better, as it can be moved to the side of the road but requires multiple firefighters to move once charged with water. The bonus is that the 5-inch can supply most apparatus to capacity with minimal friction loss. We are then limited by the water source. Many hydrant systems may not have the capacity to supply the 2,000 gpm 5-inch LDH can deliver.
Now, we get to the workhorse of the industry: the 4-inch supply hose. Because of its increased capacity over the old standard 3-inch hose, ease of use with the rubber jacket, lighter weight both dry and wet, and the amount of space required to pack more than 1,000 feet on apparatus, many departments are now using 4-inch as a standard practice. The 4-inch can supply 1,000 gpm with ease. Hoselays typically go from 100 feet to more than 1,0 feet. All in all, 4-inch seems to be ideal for supplying the apparatus we are using in communities all around the country as long as 1,000 gpm will put out your fire.
Water Delivery
Municipal water systems can provide a variety of volumes depending on the source of the water, the elevation relative to the source, and the age of the infrastructure providing the water. There will typically be large tanks on higher elevations to hold the water in reserve andprovide the head pressure for the delivery system. A treatment plant will have pump