Lauren: My colleagues Gerhard Able and Michael Wolf from the Pressure Vessel group answered your questions. Below are his answers.
1. PED defines pressure equipment to fall into the regulation with MAWP (max. operating pressure) 0.5 bar (gage) and higher. Pressure Equipment (PE) with a pressure rating of 30psi does indeed fall under the scope of the PED. The PE with a rating of 30psi does fall under the scope of the PED because of the statement in Article 1, section 1: "This directive applies....for pressure equipment and assemblies with a ...PS greater than 0.5 bar." Article 3, section 1.3 then further specifies detailed requirements for piping, as Lauren correctly points out. Air is a group 2 "liquid", thus has a category for piping starting at a DN of 32 (according to Article 3, section 1.3, second intend, and further specified in Annex II table 7). 2. DN is the unit for size (in mm) to indicate »nominal size« of tube/pipe even Flange size e.g 1" = 25 mm = DN25. DN is not a "volume-ish number". DN is defined in Article I, section 2.6, and strictly refers to the size, i.e. diameter of piping. DN is also not the actual diameter in mm, but is standardized method of referring to the diameter of a pipe. This is very similar to the system applied here in the US, where manufacturers of piping use a so called "schedule" to determine piping sizes. 3. No. Piping of group 2 content and pipe/tube DN smaller or equal 32 mm requires » sound engineering« practice (see PED Article(1.3a) and 3(3). Here; equipment can NOT be CE marked. The DN is always referring to the diameter of the pipe or component. When a valve has a DN, this DN refers to the connecting size of the valve to the piping. This means, that you have to order a valve with DN 25 if you want to connect the valve to a piping system with DN 25. 4. Concerning piping with a DN > 32 mm see PED Annex II table 7 (note: PS is max. operating pressure in bar gage) 1 bar = 14.5 psiG. There is no such thing as a "DN per meter". DN is always the standardized size of the piping or the piping component. Here are a few examples: A 1 inch pipe has a DN 25 (the actual outside diameter however is not exactly 25mm, but again this is the standardized form of how manufacturers refer to piping sizes in most of Europe). A 2 inch pipe has a DN of 50 (the actual outside diameter of the piping is 63mm). 5. Only piping of category I, II or II may receive CE marking. I hope this helps Thanks Mark A. D'Agostino US National BU Manager - Machinery, Consumer Products, Mechanical Safety 978 739 7016 md'[email protected] http://www.tuvglobal.com ---------- Original Text ---------- From: "Crane, Lauren" <[email protected]>, on 8/19/99 2:55 PM: Dear Colleagues, I am working to grasp the implications of the PED (Pressurized Equipment Directive) for our equipment. I have managed to wade through the articles and determine which Annex II tables I should be concerned with. I'm stuck on determining the "DN" value for tubing in our equipment. I gather from Article 1, 2.6 that DN is Nominal Size, and is a value assigned to piping system components. I can see from the web that some valve manufacturers provide the DN value for there products. Actually, I could only find two online hits for DN in a product spec. Our equipment is designed mainly from North American components. I doubt our suppliers "DN rate" their wares. So a couple of questions..... 1. 30 psi (2 bar) pneumatic systems in equipment for driving air cylinders and air valves and the like fall under the PED according to Article 3, 1.3, second indent (group 2 liquids)....correct? 2. DN is a volume-ish number. For example, if you have a valve with DN=10 and a length of tube connected with DN=50, then the system total is DN=60....correct? 3. While valves seem to have an unqualified DN (i.e just DN=100) rating I should expect to find tubing rated at so many DN/meter (or foot)....correct? 4. Knowing the diameter and wall thickness of a piece of tubing, how can I calculate the correct DN per meter? Thanks for any help Lauren Crane Senior Compliance Engineer Eaton Corporation --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
