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DIN 11851 couplings are often referred to as 'welding unions' or 'dairy couplings'. Where previously dairy couplings were mainly used in the dairy industry, nowadays this product has a much wider range of applications. The dairy coupling consists of four parts: a welded end piece and a threaded end piece that is fastened with a union nut. The coupling is sealed with a seal (D-ring).
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Male part
Liner
Nut
The screw coupling according to DIN 11864-1 is most similar to the DIN 11851 coupling. Both couplings consist of a welding tip piece, welding wire piece, seal and swivel nut. The main difference between this coupling is the sealing principle. DIN 11851 couplings have a D-ring and DIN 11864 couplings have O-rings. DIN 11864 couplings are a more hygienic variant of standard dairy couplings and were originally intended for the pharmaceutical industry.
The sealing principle has been developed in such a way that there is no dead space between the coupling parts and the seal, so that it fits almost seamlessly. Another difference between these two couplings is the fit. From a hygienic point of view, a DIN 11864 coupling has a lower tolerance and a tighter fit than a DIN 11851 coupling. Due to the greater tolerance of a DIN 11851 coupling, it almost always seals when, for example, piping is less well aligned.
DIN 11851 coupling
DIN 11864-1 coupling
The tube sizes according to DIN Reihe 1 and 2 are according to DIN 11851 standard. Montakon supplies these couplings in the din reihe 1, din reihe 2, inch and iso system. Dairy couplings according to DIN Reihe 1 are difficult to obtain in the market, however, Montakon has these in stock.
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* | ||
*Not standardised, but available.
At a temperature of 140°C, the following working pressures apply:
A question we get asked regurlarly: 'Which part is welded onto the installation?' The most common practice is to weld the threaded piece onto the installation. This is done because the seal can remain in the threaded piece and a threaded piece is more sensitive to possible damage.
The couplings consist of a wire piece, point piece, swivel nut, seal (D-ring), if desired, a raised T or L seal can be applied. The seals are available in various qualities: EPDM, NBR, PTFE, Silicone and Viton® (FKM) and are available with an FDA or EC1935/2004 certificate.
The couplings are produced at Montakon from forged material and are available in 1.4301 (304) and 1.4404 (316L). The pre-material must comply with DIN EN 10088-3. By default, these couplings have an internal roughness of Ra <0.8μm. These couplings are available with a 3.1 certificate according to EN 10204.
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Montakon | Titaniumlaan 120 | 5221 CL 's-Hertogenbosch | Nederland
+31(0)73 599 6000 | [email protected]
