Which of the following is a common type of pump used for transferring liquids?

All of the options listed—gear pumps, piston pumps, and centrifugal pumps—are indeed common types of pumps used for transferring liquids. Each of these pump types has its own unique operating principles and applications, making them versatile choices in various industries.

Gear pumps are typically used for pumping viscous liquids. They operate by rotating gears that trap the liquid and move it from the inlet to the outlet. This design is especially effective for applications requiring a consistent flow at a relatively high pressure.

Piston pumps, on the other hand, work using a reciprocating piston to create suction and pressure within a cylinder. This type of pump is suitable for high-pressure applications and can pump a wide variety of fluids, including those with varying viscosities.

Centrifugal pumps utilize rotational energy to move liquids. They consist of an impeller that spins and creates a centrifugal force, drawing liquid into the pump and ejecting it at high velocity. These pumps are particularly effective for low-viscosity liquids and are commonly used in water supply, sanitation, and industrial processes.

The inclusion of all these types highlights the versatility and range of applications of pumps. Hence, the most comprehensive answer includes all of them.