Many water-based fire protection systems will not work without fire pumps. The latter is used for increasing pressure – typically measured in ‘bar’ or ‘psi’ – of a water source, especially if it is inadequate for the specific system it is supplying.
Fire pumps are generally found in storage warehouses, high-rises, and other buildings with high-pressure demand. This post highlights the different types of fire pumps available.
Fire pumps are available in several varieties. This is why selecting the correct type for installation projects is crucial to avoid excessive pressures and costs that may significantly damage an entire system.
You need to take as many factors as you can into consideration. This is to prevent the installation of a fire pump that would not achieve the desired pressure requirements.
Two major categories of fire pumps exist centrifugal and positive displacement. Let’s check them out individually:
Centrifugal Fire Pump
These are the most common types of fire pump options used with various systems. The action of spinning or centrifugal pumps principally develops the pressure required.
Water in centrifugal fire pumps enters the suction inlet. It passes straight to the center of the impeller. The impeller rotates, driving the water – via centrifugal force – to the rim, eventually discharging.
Centrifugal fire pumps are designed to handle huge volumes of water while providing significantly high-pressure boosts.
Centrifugal-type pumps are available in the following configurations:
Vertical Turbine Pump
This is the only type of fire pump that the NFPA 2o (standard for the Installation of Stationary Pumps for Fire Protection) allows to easily take water under a lift condition – such as from a subgrade tank or river or another below-grade source.
Vertical turbine pumps can be used conveniently with raw water sources such as lakes, ponds, and rivers. They can also be used with electric and diesel drivers. This type of pump is available in various pressures and capacities.
In-Line Pump
If you have limited space, in-line pumps are the best option. The most common type of in-line pump is the vertical shaft type, as it comes with the driver located directly above the pump. A horizontal or vertical shaft can drive this type of fire pump.
It is also a less expensive unit that takes up limited space. However, when it becomes faulty, repairing it can be pretty expensive.
Pump repair and maintenance are difficult and expensive since the motor must be lifted off and then removed to access the pump, unlike the split-case unit.
This pump’s discharge and suction flange are positioned approximately within the same plane.
However, in-line fire pumps have limited capacities that do not exceed 5,678 L/min (1,500 GPM). They can also be used extensively with an electric driver, severely limiting their potential applications.
Horizontal Split-Case Pump
This pump is usually installed with a split casing that can easily be opened for pump maintenance access. It is connected to the driver via a horizontal shaft. Using this pump, the flow splits and enters the impeller from opposite sides of the pump’s housing.
Horizontal split-case pumps are available in several pressures and rated flow capacities. They are highly reliable and incredibly easy to maintain due to their comparatively easy split-case access.
This centrifugal pump can be used extensively with diesel and electric drivers. But they typically require a lot of space.
End Suction Pump
End suction pumps come with discharge outlets perpendicular to the suction inlets. This type of pump is generally limited to about 5,678 L/min (1,500 GPM). It is also more compact and doesn’t require much space for installation in a fire pump room. End suction pumps can be used with a diesel driver or electric driver.
Multistage Multiport Pump
Multistage Multiport pumps employ single drivers that can be diesel engines or electrical motors that connect to a pump with several impellers arranged in series within a single casing smoothly driven by horizontal shafts.
The casing of this type of fire pump has multiple discharge outlets or ports and delivers different pressures. Every port has significantly increased pressure from the impellers arranged sequentially.
A multistage multiport pump may be installed in high-rise structures with up to 30 floors. The high-rise building will be divided into three distinct zones. The multistage multiport pump should be equipped with three discharge outlets where every outlet is assigned to each of the three different zones.
The first outlet, which has a discharge pressure of 6.9 bar (100 psi), feeds lower zones or floors – i.e., from the ground floor to the 9th floor. The second outlet has a discharge pressure of 12.1 bar (175 psi) and feeds the mid-zone or middle floors – i.e., from the 10th floor to the 19th floor. The third outlet with a discharge pressure of 20.7 bar (300 psi) feeds the high zone or upper floors – i.e., from the 20th to the 30th floor.
Positive Displacement Fire Pump
Positive displacement fire pumps are generally characterized by a unique method of inducing flow by capturing a specified volume of water per pump revolution. Then push this volume of water via the discharge line.
Positive displacement pumps are designed to generate incredibly high pressures. An excellent example of a positive displacement pump is a bicycle tire pump. However, this type of pump has limited flow volume compared to its centrifugal fire pump counterpart.
Positive displacement fire pumps are also not as common as centrifugal pumps since they often have specialized use. This is mainly with foam-water and water mist systems.
Conclusion
Many types of fire pump options are available. The type of fire pump you choose depends significantly on the system you want to supply. It is also important to know the correct type to avoid excessive pressures and costs that could damage your system.
Therefore, if your system demand significantly exceeds what your water supply can quickly provide, you may have to search for the perfect fire pump that will help you out of that situation.
Reach out to Fraker Fire for more info.