Before beginning any type of project involving PVC pipe, you need to make sure you have the right pipes on hand to complete the job. PVC pipe varies according to its temperature resistance, thickness and size. After reading this guide, you'll be able to select a PVC pipe with confidence.
1. Pipe Size the size (in inches) noted by the manufacturer 2. Schedule the thickness of the pipe's inner wall. 3. Temperature Rating the maximum temperature the pipe will accommodate. 4. Price how much the pipe costs.
Choosing Pipes by Size
When you first start looking at PVC pipe, you'll notice they are separated by size. PVC comes in sizes ranging from 3/8" up to 24". One common mistake people make when purchasing PVC pipe, is assuming the pipe size listed on the side is an actual measurement of the pipe's diameter or opening. For most PVC, this isn't the case at all. PVC pipes are sized using what are called Nominal Pipe Size standards.
Nominal Pipe Size (NPS) is set of standards used in North America to ensure all PVC pipe sold is compatible across manufacturers. For many pipe sizes, the NPS and the actual outer diameter (OD) are different. For instance, the OD of a 3-1/2" NPS pipe is actually 4". You can see how this would be confusing to someone new to the world of PVC. Luckily, unless you are trying to fit NPS PVC to another type of pipe, you can purchase all your pipe and fittings using Nominal Pipe Size and rest assured that your system will fit together nicely.
If actual dimensions are important to your project, there are a few you should be aware of. Outer diameter (OD), which we mentioned earlier is the measurement from the outside wall of the pipe opening to the opposite outside wall. Inside diameter (ID) is the length between the inside wall and the opposite inside wall. Minimum wall thickness is just as it sounds; the minimum thickness you can expect at any pont in the pipe wall.
Selecting the Right Schedule
Common PVC pipe schedules range from 20 to 80. The higher the number, the thicker the interior walls of the pipe (Note: all NPS pipe of the same size will have the same OD). Pipes with thicker walls can handle a greater amount of pressure than pipes with thinner walls.
Use schedule 20 pipes for projects involving little or no pressure, such as drainage or drip irrigation systems. Schedule 40 is the recommended strength for most residential plumbing projects, while schedule 80 pipes are generally reserved for heavy-duty applications that require a stronger, more rigid pipe, such as agricultural or industrial projects.
About Temperature Ratings
A pipe's temperature rating indicates the amount of temperature it can accommodate. Most plumbing-grade pipes can handle temperatures of up to 140 degrees Fahrenheit with maximum pressure varying by pipe size and schedule. Usually these specs are printed on the pipe along with the brand and pipe size. For most residential projects, these max temperatures and pressures will be sufficient. However, you will need higher ratings for pipes that will be subjected to greater amounts of heat and pressure.
Understanding PVC Pipe Pricing
PVC pipes are typically priced per foot. In general, you will pay more per foot for PVC pipes with larger diameters. You will also pay more for pipes that can handle higher amounts of pressure. Although the price may be a factor to consider when purchasing your pipes, it is more important that the pipes you choose are appropriate for your project. Never select a pipe based solely on its price.
Many varieties of PVC pipes exist, and choosing the pipes you need for your project may seem overwhelming at first. However, by using the information contained in this guide, you can select the correct pipes every time.
Amanda Hill is the Content and Creative Manager for Commercial Industrial Supply, based out of Rock Hill, South Carolina. CIS is a supplier of PVC pipe, fittings and accessories for commercial contractors all across the United States with.