When it comes to understanding your fire safety system, there are a lot of different components to consider. The fire pump is an essential component of this system that increases water flow rate, making it easier to access plenty of water to extinguish fires anywhere in the building or space.“
Here’s everything you need to know about this essential fire safety system component, starting with what exactly is a fire pump?
What is a Fire Pump?
Fire pumps are used in water-based fire protection systems. They help to distribute water throughout the sprinkler system so every part of the building is protected in case of a fire.
Fire pumps are responsible for increasing the water pressure in order to reach the pressure demand for the building or space they’re used in. For high-rise buildings or expansive spaces like warehouses, if the existing water supply cannot provide adequate pressure to deliver water along all parts of the sprinkler system, a fire pump is required.
How Fire Pumps Work
Fire pumps work by taking the water available from the water supply and increasing the pressure. This stored energy allows water to be distributed along the sprinkler lines throughout the building. Fire pumps are typically powered by electricity, steam, or combustible fuel.
They are connected to the external water supply so levels are not affected by the building’s water use. Some fire pumps can be connected to a water source like a well or reservoir of water for that purpose.
Types of Fire Pumps
Different types of fire pumps may be used to address space and budget constraints. Fire pumps must also not excessively pressurize the water or they could damage the system. There are two main types of fire pumps: positive displacement pumps and centrifugal pumps.
Centrifugal Fire Pumps create pressure by spinning water. Water enters and is rotated by the impeller, where centrifugal force is applied. The pressurized water is then discharged into the sprinkler lines. This type of fire pump is more common and has several different configurations in order to accommodate different spaces or structures. A few of the most common configurations include:
Horizontal Split-Case Fire Pump
Vertical Turbine Fire Pump
In-Line Fire Pump
End Suction Fire Pump
Multistage Multiport Fire PumpFire Pump Maintenance and Service
If a fire pump must be used to supply your sprinkler system with adequate water pressure, regular inspections and maintenance should be performed to keep this part of the system in optimal condition.
Weekly inspections can be carried out by staff, but dedicated fire safety professionals should tend to monthly, annual, and multi-year inspections and maintenance. According to NFPA 25, fire pumps must be tested on both a monthly and annual basis to ensure that they will perform as designed. These two different tests are referred to as a monthly “churn” test and an annual flow test.
If it’s time for testing or maintenance, call Vanguard Fire & Security Systems today. Our certified fire safety professionals can help make sure your equipment meets all requirements and put you on our regular schedule for maintenance and inspections
Fire pumps are used to increase the pressure of water sourced from a municipal underground water supply piping network, or a static supply (e.g., tank, reservoir, lake). A fire pump is a centrifugal- or positive displacement- pump that has been tested and listed by a third-party testing and listing agency, such as UL or FM Global specifically for fire service use. The main standard that governs fire pump fixed-place installations in North America is the National Fire Protection Association’s NFPA 20 Standard for the Installation of Stationary Fire Pumps for Fire Protection.[1]
Fire pumps are powered most commonly by an electric motor or a diesel engine, or, occasionally a steam turbine. If the governing model building code requires backup power independent of the local electric power grid, a fire pump using an electric motor may utilize an emergency generator when connected via a listed transfer switch. Fire pumps installed on fire trucks and boats are powered by the engine of the vehicle/vessel.
Utilizing a control panel with pressure sensors, fire pumps automatically start when the pressure in the fire sprinkler system drops below a pre-designated threshold. Given the incompressibility of water, fire suppression system pressures drops significantly and quickly when one or more outlets open. Examples would be fused (opened) fire sprinklers, fire hose valves connected to a standpipe, or automatic control valves opened by release panels.
Fire pumps are utilized when determined by hydraulic calculations that the existing water supply cannot provide sufficient pressure to meet the hydraulic design requirements of the suppression system. This usually occurs if the building is very tall, such as in high-rise buildings (to overcome hydraulic head losses created from elevation differences), in systems that require a relatively high terminal pressure at the fire suppression outlets (to provide sufficient water droplet penetration of a fire plume), or in systems that require a large discharge of water (such as storage warehouses). Fire pumps are also needed if fire protection water supply is provided from a static source which provides little or no pressure. Some situations may be compounded by all of these factors, requiring large water supplies and powerful fire pumps.
Common types of fire pumps used for fire service include: horizontal split case, vertical split case, vertical inline, vertical turbine, and end suction.
A jockey pump, also known as a pressure-maintenance pump, is a small pump connected to a fire suppression system near the fire pump and is intended to maintain pressure in a fire protection piping system. These pumps recover pressures lost from gradual, slow pressure declines in a system due to temperature changes, trapped air escapement, or very small leaks. The jockey pump is essentially a portion of the fire pump’s control system. A jockey pump is sized for a flow less than one sprinkler in order to ensure a system pressure drop significant enough to start the main fire pump. Jockey pumps are typically small multistage centrifugal pumps, and do not have to be listed or certified for fire system application. The control equipment for jockey pumps may however carry approvals. Jockey pumps should be sized for 3% of the flow of the main fire pump and to provide 10psi more pressure than the main fire pump
In the United States, the application of a jockey pump in a fire protection system is provided by NFPA 20. They are inspected per NFPA 25 “Inspection and Testing of Water-Based Fire Protection Systems”.
In India, the pump manufacturers generally adhere to the TAC (Tariff Advisory Committee) guidelines, although pump manufacturers also obtain listings with UL or FM Global. For the purpose of installation & maintenance of fire-fighting pumps,
Finally, the driver of the fire pump, whether it is an electric motor, diesel engine or steam turbine, must be sized to meet the full horsepower demands of the fire pump, even if it means flowing beyond the 150% required duty point. The best way to ensure that the driver is sized correctly, and conforms to UL and FM requirements, is to review the certified factory test curve.
Look at the horsepower curve on the factory-certified test report and ensure that the power curve peaks and then begins to fall. This peak represents the highest amount of power the pump requires and the driver must be sized to meet that requirement. If the power curve is continuing to rise, the pump has not been tested to the full requirements of UL and FM, and the motor could be undersized and in violation of UL and FM.
An example of these requirements would be a fire pump UL Listed and FM Approved for 1,000 gpm at 100 psi, using an electric motor. The 150 psi at 65% point would be required to flow at 1,500 gpm while maintaining a minimum pressure of at least 65 psi. The 140% churn pressure must be less than 140 psi at 0 gpm. The pump curve (Image 1) shows a constant rise to shut off from the rated point to churn. The horsepower curve shows a peak of 86 brake horsepower (BHP) at 1,600 gpm, signaling that pump power peaks at 160% and requires a 75-hp electric motor. Many UL fire pump motors allow for a 1.15 service factor, so for this instance, a 75-hp motor provides 86.25 BHP.
Overall design and operation of fire pump installations have not changed much in the past few decades, save for some innovation on controls and other incremental improvements. However, recent developments in the industrial internet of things (IIoT) space have led to offerings that are changing the information users can glean from the fire pump and the entire fire protection system, leading to safer, more informed systems.
Up until recently, users only knew if the fire pump was on from a remote alarm but had no idea what it was actually doing. Was it flowing water or running at dead head? Was overall flow increasing over time in a fire event or had it plateaued, signaling the fire had been contained? How often was the pressure maintenance (jockey) pump running, and was there a potential leak in the system? What is the pump room temperature and is the system at risk of freezing?
Recent weather events in Texas caused many systems to freeze and break, leading to costly replacements—temperature monitoring and alerts could have helped with early action and prevention.