Class vs. Schedule PVC Pipe and What You Need to Know

06.29.11Ben Green

How do you know what pipe is right for your irrigation application?  With so many different options out there, it is easy to be pulled in the wrong direction or take some bad advice that can cost you in the long run.  Here is a brief description of the difference between Class and Schedule PVC pipe, what it is used for and it’s best application.  First let’s get started with a brief description of PVC pipe so we can cover the basics.

PVC is an abbreviation for Polyvinyl Chloride, the most common plastic in the world.  This is a solid pipe that comes in many different sizes and colors.  You commonly see it as a white color and readily available at any supply store.  This is the most commonly used type of pipe in the industry and is a common household name.  What you don’t know is that PVC pipe comes in many different colors and each color serves a very specific function.  For this phase of the conversation, we are going to ignore the colors and just concentrate on the different classifications:

• Class PVC – Look at the writing on the side of the pipe and it will either say ‘CL’ or ‘SCH’.  ‘CL’ or Class is a form of pipe that is rated for the pressure that it can withstand.  Class 200 means that the pipe can withstand 200 PSI (Pounds per square inch).  This pipe is very thin, brittle and is not flexible at all.  There are 2 main applications that it is applied: (1) In large diameter (Over 1”) and high rating (300+ PSI) for Mainline (pipe that is under constant pressure and is a water source for your irrigation valves). This is the best application for this type of pipe because the high PSI rating and the large diameter make the material less brittle. (2) In small diameter (Under 1”) and low rated (200 PSI) for Lateral line (Pipe that is not under constant pressure and is on the other side of the valve as the mainline.  Lateral’s are best described as the pipe that is directly connected to your sprinkler heads). This is the worst application because working with it is difficult and is subject to breaking and sheering.  It is use for this application because it is the least expensive pipe to use.
• Schedule PVC -  Once again look at the writing on the side of the pipe and it will say ‘SCH’.  Schedule PVC is rated by thickness of the wall of the pipe.  If you put a class pipe and a schedule pipe next to each other, you will see that the schedule pipe is much thicker than class.  This pipe is used in all different diameters for all different applications.  The pipe is flexible and does not break easily.  The pipe can also be heated up and bent if necessary.  This pipe is also more expensive due to the amount of material needed to produce a thicker-walled pipe.

As a consumer, selecting schedule pipe is always a wise decision because it truly is an easier product to work with.  If you are looking to save some money on material, you can use class pipe but you will spend your savings on labor trying to work with the material.  If you want to learn more about the different colors of  PVC, please take the time to read my blog on Color pipe.

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