Which pump is defined as a positive displacement pump characterized by gear teeth and a casing to displace liquid?

• A. End Suction Pump
• B. Fire Pump
• C. Gear Pump
• D. Horizontal Pump

Answer: (C)

The main concept here is a positive-displacement device that uses intermeshing gear teeth inside a sealed housing to move a fixed amount of liquid with each rotation. That is the defining feature of a gear pump. As the gears rotate, liquid is trapped in the spaces between the gear teeth and the casing. Those trapped volumes are carried around from suction to discharge and then expelled, creating a precise, displacement-based flow. The casing provides the enclosure that forms those trapped cavities and maintains the clearances needed for the gears to push the liquid effectively.

This description fits a gear pump exactly, because the gear teeth and the enclosing casing are what create and confine the moving liquid. The other options don’t describe this mechanism: an end suction pump is a type of centrifugal pump with the suction at the end of the pump, a fire pump refers to the application rather than the pumping mechanism, and a horizontal pump describes orientation rather than the internal operating principle.