Valve diameter Φ, diameter DN, inch” Can you distinguish these specification units?

There are often friends who do not understand the relationship between the specifications of “DN”, “Φ” and “”". Today, I will summarize the relationship between the three for you, hoping to help you!

what is an inch”

Inch (“) is a commonly used specification unit in the American system, such as steel pipes, valves, flanges, elbows, pumps, tees, etc., such as the specification is 10″.

Inch (inch, abbreviated as in.) means thumb in Dutch, and an inch is the length of a thumb. Of course, the length of the thumb is also different. In the 14th century, King Edward II promulgated the “Standard Legal Inch”. The stipulation is that the length of the three largest grains selected from the middle of the barley ears and arranged in a row is one inch.

Generally 1″=2.54cm=25.4mm

What is a DN

DN is a commonly used specification unit in China and European systems, and it is also the specification for marking pipes, valves, flanges, fittings, and pumps, such as DN250.

DN refers to the nominal diameter of the pipe (also known as the nominal diameter), note: this is neither the outer diameter nor the inner diameter, but the average of the outer diameter and inner diameter, called the average inner diameter.

What is Φ

Φ is a common unit, which refers to the outer diameter of pipes, or elbows, round steel and other materials.

So what’s the connection between them?

First of all, the meanings marked by “”" and “DN” are almost the same. They basically mean the nominal diameter, indicating the size of this specification, and Φ is the combination of the two.

for example

For example, if a steel pipe is DN600, if the same steel pipe is marked in inches, it becomes 24″. Is there any connection between the two?

The answer is yes! The general inch is an integer and directly multiplied by 25 equals DN, such as 1″*25=DN25, 2″*25=50, 4″*25=DN100, etc. Of course, there are different ones such as 3″*25=75 Rounding is DN80, and there are some inches with semicolons or decimal points such as 1/2″, 3/4″, 1-1/4″, 1-1/2″, 2-1/2″, 3-1/ 2″ and so on, these cannot be calculated like that, but the calculation is roughly the same, basically the specified value:

1/2″=DN15

3/4″=DN20

1-1/4″=DN32

1-1/2″=DN40

2″=DN50

2-1/2″=DN65

3″=DN80