Butterfly valves Series 31

The soft-sealing butterfly valve with threaded lugs (Lug Type) of the Series 31 allows just as easy disassembly and operational reliability between the discs and stem connection as the Series 30... The stem is fixed in the housing with a special stainless steel retaining ring, a thrust washer and two C-rings. These are made of brass as standard, but can also be made of stainless steel on request. The circlip can be easily removed with a standard hand tool. The stem lock prevents unintentional removal of the stem during operation. The design of the stem seal with double U-profile seal is self-adjusting and offers positive sealing properties in both directions. The extended neck provides 50mm pipe insulation and is easily accessible for direct mounting of drives. The butterfly disc and sealing face are spherically milled and hand polished to provide a blister tight seal, minimum torque and longer seat life. The one-piece body is available as an intermediate flange or flanged fitting. The polyester coating provides excellent corrosion protection. Nylon coatings are also available as an option. The double seal prevents operating media from coming into contact with the body or stem. The primary seal is obtained by a press fit between the disc and the seat ring. The secondary seal is also a press fit as the shaft diameter is larger than the diameter of the shaft bore in the seat ring.


Drinking water, waste water, sea water, heating, ventilation and air-conditioning technology.

Technical Data


Ductile Iron, Cast Iron, Carbon Steel

Nylon-Coated Ductile Iron, Aluminium Bronze, Stainless Steel, Hastelloy, Halar-Coated Ductile Iron

BUNA-N, EPDM, FKM, Polyurethane


for mounting between flanges according to DIN.

Nominal size:

DN50 - DN500

Nominal pressure:

Max. 12 bar (DN50-300)
Max. 10 bar (DN350-500)


-29°C to 204°C


Optional versions are possible.

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