The most common type of fire pump used in fire protection systems is the centrifugal pump. Centrifugal pumps are widely employed in fire-fighting applications due to their efficiency, simplicity, and reliability. These pumps use a rotating impeller to create a centrifugal force that moves water radially outward from the center of the impeller to the discharge outlet.

Centrifugal fire pumps are further classified into two main categories based on their power sources:

1. Electric Motor Driven Fire Pumps: These pumps are driven by electric motors and are commonly used in buildings and facilities with a stable and reliable power supply. They are often the primary choice for fire protection systems in urban and suburban areas.

2. Diesel Engine Driven Fire Pumps: These pumps are equipped with diesel engines and are used when there is a need for backup power in case of electrical power failures. They are often employed in remote locations, industrial sites, and areas prone to frequent power outages.

Centrifugal fire pumps are selected based on factors such as required flow rate, pressure, and the specific needs of the fire protection system they will be serving. They are designed to meet specific standards and regulations to ensure their performance and reliability during fire events.

It's important to note that while centrifugal pumps are the most common type of fire pump, there are other types of pumps, such as positive displacement pumps, that can be used in certain specialized applications or for specific requirements. The choice of the most suitable fire pump depends on factors like building size, fire suppression system design, available water source, local regulations, and other site-specific considerations.