An important part of many water-based fire protection systems is the fire pump. They are used to increase the pressure (measured in psi and bar) of a water supply when a water source is not sufficient for the system it supplies. They are often found in buildings with high-pressure demands, such as high-rise buildings or storage tanks.

There are many types of fire pumps available. Choosing the right type of pump for the installation project is important to avoid excessive costs and to avoid excessive pressures that can damage your system. If all factors are not considered, it can result in a pump installation that does not meet the necessary pressure requirements which may require a new pump to be installed.

There are two main categories of pumps: positive displacement and centrifugal.

Positive Displacement Pumps

Positive displacement pumps are characterised by the method of generating flow by capturing a certain volume of water per pump and pushing it out of the discharge line. A bicycle tyre pump is an example of a common positive displacement pump. Positive displacement pumps generate very high pressures but have limited flow volumes compared to centrifugal pumps. They are not common as they have a specialised use, especially with water-mist and foam-water systems.

Centrifugal Pumps

Centrifugal pumps are the most common fire pumps and are used in most systems. Pressure in centrifugal pumps is developed mainly by centrifugal force or rotary motion. In centrifugal pumps, water enters through the suction inlet and passes to the centre of the impeller. The rotation of the impeller moves the water by centrifugal force towards the edge where it discharges. Centrifugal pumps can handle large volumes of water while providing high-pressure increases.

The following are different centrifugal-type pump configurations:

Horizontal Split Case Pump

In the horizontal split casing pump, the flow is split and enters the impeller from opposite sides of the pump casing. As the name suggests, this is a split casing pump that can be opened for maintenance access and is connected to the drive by a horizontal shaft.

They are very reliable, have a wide range of rated flow and pressure capacities, are easy to maintain due to their relatively easy split case access and can be used with both electric and diesel drives. However, they also typically require the most space of any type of fire pump.

End Suction Pump

An end suction pump has a discharge outlet perpendicular to the suction inlet. These pumps are typically limited to a capacity of approximately 1,500 gpm (5,678 L/min). Compared to horizontal split fire pumps, they are more compact and require less installation space in a fire pump room where available space is at a premium. End suction pumps are available with the electric drive or diesel drive.

Multistage Multipoint Pump

Multistage Multiport pumps utilise a single drive, which can be an electric motor or diesel engine, connected to a pump with multiple impellers in series within a single casing driven by a horizontal shaft. The casing has multiple ports or discharge outlets providing different pressures – each port having increasing pressure from successive series of impellers.

The result is several different pumps that can be used in a variety of situations. When your system demand exceeds what your water supply can provide, it’s time to look at what a fire pump can do to help fill that gap.