A fire fighting water pump is critical for ensuring that your sprinkler system and other fire safety systems are properly supplied with adequate water pressure. While weekly inspections can be done by staff, dedicated fire safety professionals should perform monthly and annual inspections and maintenance.
When choosing a fire pump, there are two important numbers to keep in mind: PSI and GPM. Both are vital for understanding the performance of any fire pump.
PSI & GPM
The fire fighting water pump’s rated pressure (or PSI) indicates the maximum amount of water it can produce at its rated speed. The gallons per minute (GPM) is how much water it can supply at the rated pressure.
Typically, the fire pump size is determined by the most hydraulically demanding area of the system. In high-rise buildings, this is often the automatic fire standpipe demand. In other situations, the most demanding area could be a specific hazard.
Fire fighting water pumps are also used to supplement hydrant supplies, for example in a pumper relay operation. For this, a pump nozzle is installed on the fire truck and set to operate at the preconnect nozzle pressures below. Officers can then vary the nozzle pressure as needed to achieve acceptable fire stream performance at the scene. These nozzles can track the water supply, monitor hose line pressures and flow, and display all of this data on a convenient touch screen interface.
Horizontal Split Case
The horizontal split case fire pump is commonly used in commercial high-rise buildings, warehouses, airports, and industrial facilities. These fire pumps are NFPA-20 design and UL Listed.
The main advantage of the HSC over other fire pump types is that the shaft is located between bearings, allowing for increased support and stability at higher torque and speed ratings. They also have threaded ports near the suction and discharge flanges to allow for the installation of pressure gauges.
Another benefit of the HSC is that it does not require a concrete housekeeping pad and is less susceptible to mechanical damage caused by water turbulence compared to end suction pumps. However, the pump’s churn pressure and maximum discharge head rating must be within the limits of the test header’s capacity.
Another downside is that the HSC requires a larger footprint than an end suction pump, and its large flanges, larger impellers, and overall size for the split housing seal joints make them more expensive at initial purchase and installation.
Electric Motor-Powered Engines
Electric fire fighting water pumps are the most common type of pump. They are cheaper and require less inspections than their diesel-powered counterparts. However, the biggest downside to an electric pump is that it can’t run when power fails, meaning your fire sprinkler system won’t work when needed.
A backup generator should be used in conjunction with an electric pump to ensure the fire fighting system remains active during power outages. This also allows you to avoid a costly rebuild or retrofit of your fire protection system when compared to a diesel-driven engine.
Each fire pump should undergo full annual testing that puts the system through its paces and verifies it’s operating effectively. During this test, the technician will measure the pressure and flow of the fire fighting water pump to compare results to original design specifications. This will help identify if the system is operating within code requirements and can be used to pinpoint any problems quickly so they can be addressed.
If your system demand exceeds what your water source can provide a vertical turbine pump is often the solution. These pumps have a low footprint and don’t require priming as long as minimum submergence requirements are met because their impellers remain immersed in water at all times. They also offer flexible staging so you can achieve your capacity requirement with a minimal amount of floor space.
They are the only type of fire pump allowed by NFPA 20 that can take in water under suction lift (from below grade). Standard construction features cast iron discharge heads, a fabricated steel column, stainless steel head and bowl shafts, or alloy steel line shafts with bronze fitted bowls.
They are easy to customize and can be powered by gas or electric motors. They require routine maintenance including cleaning, lubrication and inspections of the motor windings, firmware and bearings. Remember to follow your manufacturer’s recommended schedule for maintenance so you can keep your fire fighting water pump operating at peak performance.