If the tank pump truck has its own water tank, the tank capacity is generally 4000 liters. Usually, the water tank is located inside the car, and the water pipe passes through the middle of the car. A 15 cm diameter hard suction pipe is used to pump water from an external source such as a swimming pool or lake. Water can also flow from the fire hydrant into the pump.
At the heart of the tank pump is the pump impeller, a rotor-like component with curved blades. The impeller is driven by its own diesel engine and rotates at high speed inside the pump. When water flows into the pump, it hits the inside of the impeller and the water flow is pushed backwards. The impeller rotates to generate centrifugal force and form a water pressure. Open the valve and the water flow hits the center of the impeller.
Firefighters control the hoses through the pump control panel. The control panel consists of a set of levers and switches that control the amount of water and which stream the water flows into. A large pump can have multiple hoses at the same time. When the firefighter arrives at the scene of the fire, the driver will jump off the car, rush to the control panel and start operating the pump. The driver can know the amount of water remaining in the tank by the obvious indicator on the dial on the control panel or in the group red light. Other firefighters will connect the pump to a new source of water.
The first thing the driver has to do is to confirm that the valve between the tank and the pump is open. Press the electric switch next to the pump, the valve will open and the water will flow into the pump. Next, the driver needs to confirm which water pipes (or hoses) have been removed from the fire truck by the firefighters, and he has to fill the water pipes. When water flows from the water pump into the water pipe, it means that the water pipe has been filled with water. The pipes are marked with different colours and the driver can easily identify which pipes have been filled. The color of the water pipe is the same as the color of the metal plate under each joystick of the control panel.