It is hard to believe that something as simple as finding out the size of a pipe for a fitting or a fitting for a pipe is actually more complicated than it appears at first glance.
Many of the customers that have problems with finding the right fitting end up asking us the very common question about pipe dimensions and finding the right fitting. To simplify the process, and to provide more of an explanation, let’s look at the issues a bit more closely.
Sch 40 and Sch 80 Pipe
Rigid PVC pipe will either be marked as sch 40 or sch 80. The sch stands for schedule, and this is actually the thickness of the wall of the pipe. It has nothing to do with the exterior diameter of the interior diameter, but it does impact the interior diameter for obvious reasons.
Either sch 40 or sch 80 pipe will have the exact same exterior diameter or the size of the pipe when measured from the outside. However, because the sch 80 is designed to handle more pressure, that interior wall is thicker, meaning the interior diameter is smaller even with the same size of exterior.
Fittings
If you look on the exterior of any plumbing pipe, or standard PV pipe, you should be able to find the information on the size of the pipe. However, if you cannot, or if you are using furniture grade PVC that doesn’t have this printed on the outside, you can still figure it out.
Start by measuring the interior diameter of the pipe, this is the only important pipe dimensions to worry about. There is a chart provided here that allows you to find the interior diameter (ID), in the first column in the yellow section and then move over to the far left column and find the size of pipe to buy.
If you are using a pipe under pressure, that sch 80 pipe, you will do the same but find the ID measurement, in inches, in the first column in the green area of the chart.
This can be confusing for a lot of people, especially when it comes to determining the correct fittings. If you are ordering online and have any questions, don’t hesitate to contact FlexPVC and we can always walk you through what you need to measure to make sure you are using the right pipe dimensions.
