In the renovation of hydropower or municipal drainage projects, many people will encounter the words "PVC100 drain pipe" and "DN100 drain pipe" - although the number is 100, the actual pipe selection is often stepped on the pit: either the purchased pipe cannot be connected to the accessories, or the size does not meet the design requirements. The root of the problem lies in not understanding the core logic and size correspondence of the two signs. Today we will pierce this layer of window paper and make it clear at one time.

First of all, it must be made clear that "DN" and "PVC + number" are two completely different sign systems.

first refers to "DN" in "DN100" - it is the abbreviation of "Nominal Diameter", which is the "common language" of the plumbing industry. The nominal diameter is neither the actual inner diameter nor the outer diameter of the pipe, but the "nominal size" set to unify the connection size of pipes, valves, joints and other accessories. For example, the DN100 drain pipe, whether it is PVC, cast iron or steel pipe, their interface threads and flanges are the same size, but the actual diameter will vary depending on the material: the outer diameter of the steel pipe DN100 is about 108mm, and the outer diameter of the PVC pipe DN100 is 110mm (this is the key, remember).

Look at the "PVC100 drain pipe" again - the "100" here is actually the actual outer diameter of the PVC pipe (De, External Diameter). In the production standard of PVC-U drain pipe, the outer diameter is the core size parameter (because the PVC pipe is connected by socket, the outer diameter determines whether the accessories can be inserted), so the industry is accustomed to directly use "PVC + outer diameter number" to refer to the pipe, such as "PVC110" is the PVC drain pipe with an outer diameter of 110mm. And many people say "PVC100", either a simplified misrepresentation of "DN100 PVC pipe", or a confusion of the outer diameter and nominal diameter numbers - regular PVC drain pipe does not have the standard specification of "PVC100", because the outer diameter of the PVC pipe corresponding to DN100 in the standard is 110mm (ie De110), De100 PVC pipe is a non-standard size and is rarely used in engineering.

Now back to the core question: What is the difference between PVC100 and DN100?

1. The logo logic is different: DN100 is the "nominal diameter", which solves the problem of "whether the accessories can be connected"; PVC100 (if understood by misnomer) is the "outer diameter logo", which solves the problem of "the actual size of the pipe".

2. The size corresponds to different: if "PVC100" is misnomer (actually refers to DN100 PVC pipe), then its corresponding outer diameter is 110mm (De110); if it is a real De100 PVC pipe (non-standard), then its outer diameter is 100mm, and the corresponding nominal diameter is actually about DN80 (because the standard outer diameter of DN80 PVC pipe is 90mm).

3. The application scenarios are different: DN100 is the most commonly used logo in the design drawings (for example, "the bathroom drainage riser adopts DN100 drain pipe"), which corresponds to De110 PVC pipe; while "PVC100" is either a colloquial error or a non-standard pipe in a special scene, which will hardly appear in the formal design.

In actual construction, the easiest pit to step on is "buy DN100 as PVC100" - for example, the designer marked DN100, but you bought De100 PVC pipe (outer diameter 100mm). As a result, the accessory interface is made according to DN100 (corresponding to the inner diameter of about 110mm), and the pipe cannot be inserted at all, so it can only be reworked. On the contrary, if someone says "PVC100 pipe", you must first ask: is it De100 (non-standard) or DN100 misnomer?

summarize the key conclusions:

- DN100 is the nominal diameter, which is the "universal code" for the connection of accessories;

- the outer diameter of the standard DN100 PVC drain pipe is 110mm (De110);

- "PVC100" is either misnamed or a rare non-standard pipe.

Understand these three points, whether it is buying pipes, construction or communicating with workers, it will no longer confuse "PVC100" and "DN100". After all, the core of drainage engineering is "pass". The first step is to choose the right pipe to avoid subsequent troubles.