DIN 11851 Coupling
The so-called “Milk coupling” according to DIN 11851 is the most commonly used screw coupling in the food industry. The round thread and the large tolerances ensure that the coupling can always be closed in practice. If necessary, with an increased seal. However, this is no longer entirely up to date, but it does indicate that the link is very user-friendly and is probably why it is so popular. The coupling is officially only standardized in NW sizes, but versions for inch or ISO sizes are available. Many fittings or instruments are equipped with a coupling part according to DIN 11851. SKS has both forged and cast versions in its program. Size range and material according to DIN 11850 and EN 10357. Forged front material must be used in accordance with the standard, the version produced from cast front material is also available. This version is not available with certificates from SKS.
DIN 405-1 and 2, DIN 11887, DIN ISO 2768-1, ISO 48, FDA and BGA Versions and codes:
- Point D,
- Threaded piece C,
- Gland F and seal G; internal Ra value < 1.6µm
Other connections not standardized: Blind, Hose tail, screw-in or screw-on. Seals EPDM, FKM (Viton), HNBR, MVQ (silicone), NBR or PTFE (Teflon)
Seals
EPDM, FKM (Viton), HNBR, MVQ (silicone), NBR or PTFE (Teflon)
- DN10 – DN40 max. 40 bar
- DN50 – DN100 max. 25 bar
- DN125 – DN150 max. 16 bar
- DN200 max. 10 bar
Particularities
In accordance with EHEGD if fitted with SKS seal or in combination with the SKS adapter and seal.
DIN 11851 dimensions
DIN Reihe 1 and 2 tube sizes adhere to the DIN 11851 standard, with SKS providing these couplings in various systems including DIN Reihe 1, DIN Reihe 2, inch, and ISO. While DIN Reihe 1 dairy couplings may be scarce in the market, SKS consistently maintains them in stock, serving as your premier distributor.
| DIN Reihe I (standard) | DIN Reihe II (standard) | ISO | INCH |
| 12 x 1,5 | 13 x 1,5 | 17,2 x 1,6 | 12,7 x 1,65 |
| 18 x 1,5 | 19 x 1,5 | 21,3 x 1,6 | 19,05 x 1,65 |
| 22 x 1,5 | 23 x 1,5 | 26,9 x 1,6 | 25,4 x 1,65 |
| 28 x 1,5 | 29 x 1,5 | 33,7 x 2,0 | 38,1 x 1,65 |
| 34 x 1,5 | 35 x 1,5 | 42,4 x 2,0 | 50,8 x 1,65 |
| 40 x 1,5 | 41 x 1,5 | 48,3 x 2,0 | 63,5 x 1,65 |
| 52 x 1,5 | 53 x 1,5 | 60,3 x 2,0 | 76,2 x 1,65 |
| 70 x 2,0 | 70 x 2,0 | 76,1 x 2,0 | 101,6 x 2,10 |
| 85 x 2,0 | 85 x 2,0 | 88,9 x 2,0 | |
| 104 x 2,0 | 104 x 2,0 | 114,3 x 2,3 | |
| 129 x 2,0 | 129 x 2,0 | 139,7 x 2,6 | |
| 154 x 2,0 | 154 x 2,0 | 168,3 x 2,6 | |
| 204 x 2,0* | 204 x 2,0* | ||
- Tube size 12 mm to 41 mm: 40 bar
- Tube size 52 mm to 104 mm: 25 bar
- Tube size 129 mm to 154 mm: 16 bar
- Tube Size: Denoted by DN size, measuring pipe size.
- Standards: Adhering to DIN 11851.
- Material: Typically 1.4301 / 1.4307 / 1.4404 / 1.4432.
- Heat Number: Unique code for product origin identification.
One common query is, "Which part should be welded onto the installation?" Typically, the threaded piece is welded, as it maintains the seal and is less prone to damage.
SKS produces these couplings from forged materials, offering options in 1.4301 (304) and 1.4404 (316L) grades, complying with DIN EN 10088-3 standards. Default internal roughness is Ra <0.8μm, with available 3.1 certificates according to EN 10204.a
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