Allectra Ltd.

44 1825 721900

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Nominal Internal Diameters (DN) and Flange Sizes

Allectra uses the internationally accepted system of nominal internal diameters (DN) to identify flange sizes.

These correspond with other naming conventions as shown in the following table. The DN convention applies to Copper Gasket Flanges (CF Types), Clamp Flanges (KF Types) and ISO-K and ISO-F Flanges (LF Types). The sizes DN25 and DN50 are not in common use for CF flanges.

Additionally there are sizes DN80 (4 5/8”), DN125 (6 3/4”) and O.D.s 13 1/4”, 14” (300CF) and 16 1/2” (350CF).

These are available on request.

ISO-K Flanges are standardised up to the size 630, ISO-F Flanges up to the size 1000.

In addition to CF, KF and ISO-K/F, we can offer flanges as well as components on the following flange types:

  • JIS standard (Size 10 to 300, mainly used in Asia)
  • CeFix Flanges (EVAC registered design and trade mark)
  • sTeRic TM Clamp Flanges (mainly used in Pharmacy, Medicine and Biology)
  • EVAC ISO-Tapered Flanges (ISO-Type for closure by chains)
  • Flanges according to customer drawings.


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