Which type of fitting is used to connect pipes of different sizes?

The type of fitting that connects pipes of different sizes is a reducer. Reducers are specifically designed to allow for a smooth transition between two different diameters of pipe, accommodating the change in pipe size while maintaining the flow of fluid through the system. They can be found in various configurations, such as concentric or eccentric, depending on the application and design requirements.

Understanding the role of each fitting type clarifies why reducers are essential. Elbows are used to change the direction of the piping, tees provide branches within a piping system, and caps are used to close the end of a pipe. These fittings do not serve the purpose of connecting pipes of differing diameters, which is why reducers are the appropriate choice for this function.