What does the Standard Dimension Ratio (SDR) in PVC pipe represent?

The Standard Dimension Ratio (SDR) in PVC pipe is a critical measurement that helps in identifying the wall thickness relative to the outer diameter of the pipe. Specifically, SDR is defined as the ratio of the outer diameter of the pipe to its wall thickness. This ratio provides essential information on the pipe's strength and its ability to handle internal pressure; the lower the SDR, the thicker the walls of the pipe in relation to its diameter, which typically translates to a pipe that can withstand higher pressures.

In practical terms, SDR is used widely in piping specifications because it allows engineers and technicians to compare the strength and pressure handling capabilities of different pipe materials and sizes easily. Each SDR corresponds to a specific wall thickness for a given outer diameter, facilitating the selection of the appropriate pipe for various applications in wastewater and other fluid transportation systems.