What is the spiral-shaped casing that surrounds a pump and collects the discharge?

The spiral-shaped casing around a pump that collects the discharge is known as the volute. The volute is a crucial component of many centrifugal pumps, as it is designed to convert the kinetic energy from the fluid flow, which has been imparted to it by the impeller, into pressure energy. As fluid exits the impeller, it enters the volute, where the cross-sectional area increases, allowing the fluid to decelerate and build pressure. The shape of the volute facilitates uniform fluid distribution to the discharge piping, ensuring efficient and stable operation of the pump.

In this context, it’s important to understand the roles of other components in relation to the volute. The impeller generates the flow and pressure, while the packing gland serves to prevent leakage from the pump shaft, and a sleeve can refer to various protective or supportive components in mechanical systems. However, none serve the same purpose as the volute in collecting and managing the flow of discharge, which is why the volute is specifically identified as the correct answer.