How can beginners easily determine the DN value? 300LB and 150LB?
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Extremely insensitive to numbers! ! :)They often get the DN value wrong. I’m asking if there are any better ways. How did you guys manage to do it back then?
I didn’t understand what LZ meant. .
Refer to the French standard. . . Check fitting standards
Study the attitude a bit; if you’re not sure, use calipers to measure the dimensions and follow the specifications one by one! The method isn’t stupid; once you make a mistake, you’ll realize just how scientific this method is!
Look more often; keep a ruler in your pocket, and measure things frequently to reinforce your understanding
DN refers to the diameter, that is, the diameter of the valve, with the unit usually being mm. 300LB and 150LB refer to the American standards regarding the pressure capacity of the valve
1. Ask the owner or on-site personnel directly, or check the archived drawings. If this doesn’t work, try the second one. 2. Go to the site to check the markings, the steel stamps, and the nameplates. It’s usually indicated there; if it’s not marked or has been there for a long time so it’s hard to see, check the third point. 3. Use a ruler to measure the outer diameter and key dimensions of the pipes and fittings. For the flange, measure its outer diameter, the outer diameter of the bolt holes, its thickness, and then count the number of bolts. For valves, it’s also possible to measure the end-to-end dimension. These are all relatively easy to measure. By comparing the measured data with the data in the standards, it can be determined! It is recommended to bring a thin thread along; since it’s impossible to tell the outer diameter of the tubes, wrap the thread around them once, measure the length of the thread to determine the outer diameter, and then convert it to the diameter. 4. The pressure rating can also be inferred from the operating conditions. For flanges made of a given material, the temperature and pressure curve is fixed; the temperature and pressure values must fall within the range specified for that flange in order to be used. Of course, this requires experience. 5. As for the insulation wrap being tightly sealed, to be honest, there was nothing I could do; I had to pry it open to take a look.