Determining the precise outer diameter of 1 1/2" PVC pipe isn't as straightforward as it might seem. The "1 1/2 inch" designation refers to the nominal size, not the actual outer diameter. This is a common point of confusion in the plumbing and construction industries. This guide will clarify the nuances and provide you with the information you need.
What Does "1 1/2 Inch PVC" Actually Mean?
The 1 1/2" designation for PVC pipe refers to its nominal inner diameter (ID), not its outer diameter (OD). Manufacturers use this system for historical reasons and for simplifying pipe fitting selections. The actual inner diameter might vary slightly depending on the manufacturer and the pipe's schedule (a measure of its wall thickness).
So, What IS the Outer Diameter of 1 1/2" PVC Pipe?
Unfortunately, there's no single definitive answer. The outer diameter depends on the schedule of the pipe. Schedule 40 is the most common type used in residential plumbing, while Schedule 80 offers greater strength and pressure resistance. Here's a breakdown:
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1 1/2" Schedule 40 PVC: The outer diameter is approximately 2.067 inches.
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1 1/2" Schedule 80 PVC: The outer diameter is approximately 1.900 inches.
As you can see, the difference is significant. Always verify the pipe's schedule before relying on any measurement. The schedule is usually printed on the pipe itself.
How to Measure the Outer Diameter Yourself
If you need a precise measurement and don't have access to the pipe's specifications, you can measure it directly:
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Use a caliper: A digital caliper provides the most accurate measurement. Simply place the jaws around the pipe and take the reading.
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Use a ruler and string: Wrap a string around the pipe's circumference, mark the point where it overlaps, and then measure the string length with a ruler. Divide this length by π (approximately 3.14159) to obtain the diameter. This method is less precise than using a caliper.
What is the Inside Diameter of 1 1/2" PVC Pipe?
As mentioned earlier, the nominal size (1 1/2") is closer to the inside diameter. However, the actual inner diameter can vary slightly based on the schedule. For general purposes, you can expect an inner diameter close to 1.5 inches, but it's always best to consult the pipe's specifications for precise measurements.
What is the Wall Thickness of 1 1/2" PVC Pipe?
The wall thickness also varies with the schedule. Schedule 40 PVC typically has a thicker wall than Schedule 80, but the Schedule 80 PVC has a smaller OD resulting in a thinner wall than Schedule 40. Always check the manufacturer's specifications for precise wall thickness.
Which Schedule of PVC Pipe Should I Use?
The choice between Schedule 40 and Schedule 80 depends on the application:
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Schedule 40: Suitable for most residential plumbing applications where pressure requirements are moderate.
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Schedule 80: Offers greater strength and pressure resistance and is often preferred for underground applications or high-pressure systems.
This comprehensive guide should help you understand the nuances of 1 1/2" PVC pipe sizing. Remember always to verify the schedule of the pipe to ensure accurate measurements. Using the correct size and schedule is crucial for a safe and functional plumbing system.
