The difference between De, DN, d, and ф

1.DN refers to the nominal diameter of the pipe, which is the average of the outer diameter and the inner diameter. The value of DN = the value of De - 0.5 * the thickness of the pipe wall.

Note: This is neither the outer diameter nor the inner diameter. This is a standardized diameter series for pipes and their accessories.

The use of nominal diameters is conducive to the standardization of parts and components, and is also convenient for design, manufacturing, repair and management, reducing manufacturing costs. For pipes, DN is a size that is smaller than the outer diameter and larger than the inner diameter. Corresponding to a certain nominal diameter of the pipe, its outer diameter is a certain value, and the inner diameter varies with the wall thickness.

Its correspondence with the imperial unit is as follows:

Pipes such as water and gas transmission steel pipes (galvanized steel pipes or non-galvanized steel pipes), cast iron pipes, steel-Plastic composite pipes and polyvinyl chloride (PVC) pipes should be marked with the nominal diameter "DN" (such as DN15, DN50).

2.De mainly refers to the outer diameter of the pipe. The outer diameter of PPR, PE pipe, and polypropylene pipe is generally marked with De. It needs to be marked in the form of outer diameter * wall thickness, such as De25×3.

3.d generally refers to the inner diameter of the pipe, the diameter of the inner circle of the inner wall of the pipe.

4. Φ: refers to the outer diameter of the pipe, that is, the outer diameter of the pipe including the pipe wall thickness. Generally, seamless steel pipes and spiral steel pipes are marked with Φ to indicate the specifications and sizes, and are marked in the form of outer diameter x wall thickness. For example: Φ108×4, which means a pipe with an outer diameter of 108mm and a wall thickness of 4mm.