In a fire situation, every second counts and a fire pump can make the difference. These high-pressure pumps can move gallons of water per minute to where they are needed in order to keep firefighters safe and extinguish the fire. When designing and installing a fire system, it is important to consider these critical pumps for optimal performance.
In general, fire pumps are installed when the local water supply cannot generate enough hydraulic pressure to satisfy demand from a standpipe or sprinkler system. Typically this is on high-rise buildings where gravity alone can’t provide the pressure required to reach the top floors of the building.
There are a number of types of fire pumps on the market and each has their advantages and disadvantages depending on the specific application. For example, horizontal split case fire pumps are very reliable and come in a variety of rated flow and pressure capacities. They are relatively easy to maintain due to the split casing that can be opened for pump maintenance access and are compatible with both electric motors and diesel drivers. However, they do require more space for installation than other types of fire pumps.
Whether a single or two-stage fire pump is selected, it is important that the hydraulic design of the system and the nozzles used to apply the extinguishing agent are taken into consideration. Also, determining the flow rates and discharge pressures required is important in deciding on the correct type of pump for an application.
Another consideration is the power sizing of the fire pump driver. This is based on the fire pump’s hydraulic design and can be determined by looking at the pump’s rated power curve. NFPA codes differ from jurisdiction to jurisdiction, but in general they require the driver to be sized a minimum of at 150% of the maximum rated duty point.
Finally, the fire pump must be connected to a reliable power source and this is codified in NEC 695.3. This can be from a single, dependable source such as a generator or multiple sources that are synchronized in time and in sequence.
Lastly, fire pump systems are subject to full annual testing that puts the entire system through its paces by measuring water pressure and flow. These tests are normally conducted by a licensed professional. During these tests, the fire pump is run at the rated churn flow for one hour while the pressure and motor readings are recorded. The 2-1/2-inch fire department valve outlets are then closed in a controlled manner to bring the pump back down to churn.
All these requirements are important to ensure that the fire system works properly in the event of an emergency. It is also critical that the inspection, testing and maintenance of fire pumps is done by a licensed professional to avoid any issues or damage that could compromise its performance during an actual emergency.