In piping terminology, what is a 'reducer'?

A reducer is defined as a fitting that connects pipes of different diameters. This is fundamental in piping systems because transitions between various pipe sizes are often necessary for purposes such as flow management, pressure considerations, and space constraints.

In practical applications, a reducer enables the system to function efficiently by facilitating the movement of fluid from a larger diameter pipe into a smaller diameter pipe or vice versa. This helps maintain the desired flow rate and can prevent issues such as pressure drops or turbulent flow that could occur if mismatched pipe sizes were used without such fittings.

The other options reflect misunderstandings of pipe fittings: there are specific fittings designed solely for connecting pipes of the same diameter, mechanisms for pressure regulation, and expanding pipe types, none of which align with the definition and purpose of a reducer.