There are many factors to consider when choosing the right fire fighting water pump. The correct combination of horsepower, flow rate and pressure is critical to ensure that the pumps can be effective on the fire ground, provide sufficient potential pressure to reach difficult areas, conserve energy and limit wasted water.
Whether you’re looking for a centrifugal, turbine or positive displacement style fire pump, the first step is to determine what the job requires and what capacity range will work best. Pump sizing is accomplished by performing a gallons per minute (gpm) and pound per square inch (psi) calculation for the structure you’re working on. GPM and psi relate to each other, with higher GPM usually having lower psi, and vice versa.
In order to calculate the gpm requirements for a specific structure, you’ll need the building’s floor plan and size information as well as the type of sprinkler system it is equipped with. If the structure is a high rise, you’ll need to perform two calculations—one for the highest occupiable story and one for the lowest floor with fire department vehicle access. The gpm calculation is used to determine what size sprinkler system the structure will require and the psi calculation is used for high rise buildings to ensure the fire pump can deliver 100 pounds per square inch of pressure to the top of the building while flowing its rated gallons per minute.
While this may seem like a lot of information to collect, it’s important to get the calculations as accurate as possible. Too low of a pressure will result in not being able to fill the hoselines with enough water to extinguish a fire and too high of a pressure can result in injuring the crew members inside the building.
Getting the calculations right is key to making sure the fire fighting water pump will be effective. Once you have the gpm and psi required for the structure, you can choose between a horizontal split case, vertical inline or a vertical turbine fire pump. The most common choices are the horizontal split case and vertical inline fire pumps. The price difference between these types of fire pumps is largely related to the pump’s horsepower rating and the type of controller it uses.
The pump you choose is also influenced by your location and available space, as well as the cost of installing and maintaining a fire pump. For example, a horizontal split case fire pump typically costs more than a vertical inline fire pump for similar size ratings. In addition, a larger fire pump generally requires a larger diameter piping and more sophisticated controls than smaller pumps.
Finally, the installation of a fire pump is typically only necessary when the hydraulic demand of systems like automatic sprinklers or standpipes exceeds the capacity of the city water supply line. However, you can also install a fire pump to increase the hydraulic pressure for systems even when you’re operating on an existing water supply.
