Sanitary butterfly valve with a male threaded DIN 11851 union end, so it can be removed from the line without cutting pipework. Used for shut-off on hygienic process lines in dairy, beverage and food plants.
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The valve closes by rotating a disc a quarter turn about an axis across the bore, into an elastomer seat carried in the body. The seat is both the seal and the wearing part, and it is the item a maintenance store keeps.
This version carries a male threaded end of the DIN 11851 union system, which means it is joined with a slotted round nut and a gasket rather than welded. The joint can be broken by hand with a C-spanner, so the valve can be taken out for inspection or seat replacement without cutting the line — the reason a threaded valve is specified in plants that strip down for cleaning.
Wetted parts are austenitic stainless steel, in practice AISI 316L (1.4404) for the disc and body halves, with AISI 304 (1.4301) for the nut and handle and a product-contact finish of Ra 0.8 µm or better. Choose the seat and the union gasket together and for the product: EPDM for dairy, water and CIP but not for oils and fats; NBR for fats and oils to about 95 °C; silicone for wide temperature swings but not hot water or steam; FKM to about 180 °C away from hot water, steam, lye, acid and alcohol.
State the nominal size, the end form at each end, the seat and gasket materials, the handle type and whether an actuator is required. The DIN 11851 system is not interchangeable with the other hygienic union systems: the tube outside diameters differ, and so do the thread and the sealing geometry.
| Valve Type | Quarter-turn butterfly valve with a male threaded end; the disc seals into an elastomer seat carried in the body |
|---|---|
| Connection | Male threaded end of the DIN 11851 union system (Gewindestutzen), with a round thread to DIN 405-1 that can be run up by hand; the joint is completed by a conical liner, a slotted round nut and a D-ring gasket |
| Size Range | EN 10357-A (former DIN 11850 Reihe 2) tube, DN10 to DN200 — outside diameter 13, 19, 23, 29, 35, 41, 53, 70, 85, 104, 129, 154 and 204 mm. The DN label is neither the bore nor the outside diameter |
| Connection Pressure Rating (DIN 11851 union) | DIN 11851 screw connection: 40 bar for DN10-DN40 falling to 25 bar for DN65-DN100 and 16 bar for DN125-DN150, usable to a maximum of 140 °C. The DN50 figure is manufacturer-dependent and is published as either 25 or 40 bar — this rates the union, not the valve. A sanitary butterfly or check valve is rated well below its DIN 11851 union, so obtain the valve's own pressure rating for the size ordered |
| Wetted Material | Austenitic stainless steel; specify AISI 316L (1.4404) for the disc and body halves and AISI 304 (1.4301) for the nut, handle and non-wetted parts |
| Surface Finish | Ra < 1.0 µm on finely finished product-contact surfaces; Ra ≤ 0.8 µm is the finish usually quoted for hygienic service |
| Seat / Seal Material | Elastomer seat and union gasket to be specified — EPDM, NBR, VMQ (silicone), FKM or PTFE — compatible with the product and the cleaning fluids |
| Applicable Hygiene Standard | 3-A 57-02 Disc-Type Valves is the applicable class for this type of equipment. The goods are not asserted to carry the 3-A Symbol |
| Certification to Specify | EN 10204 3.1 inspection certificate for wetted stainless steel parts |
