Question: what is the difference between schedule 40 and schedule 80 pvc?
Answer: The difference is in the inside diameter or I.D. of the pipe. Schedule 80 PVC pipe will have a smaller inside area than Schedule 40 pipe because of its thicker wall. For that reason, flow is more restricted in Schedule 80 pipe vs Schedule 40 of the same size. The same is true of PVC fittings in both schedules.