EN 593 Double-Shaft Wafer Butterfly Valve

Metalsin supplies double-shaft wafer type butterfly valves manufactured in accordance with EN 593. These valves are widely used in water treatment plants and water supply and distribution lines.

Double Shaft vs. One-Piece Through Shaft

The shaft of a butterfly valve, also known as “stem”, is a bar extending through the body hubs and into the disc to support the disc and transmit operating torque to the disc-closure member. Each valve shall have a one-piece shaft or a double-shaft arrangement. The conventional wafer butterfly valve supplied by Metalsin has a one-piece through shaft, which is a single continuous shaft extending completely through the valve disc and is fixed to the disc. The double-shaft arrangement has two stub shafts which are two separate shafts located on both top and bottom sides of the disc. The two stub shafts do not penetrate the valve disc; instead, they are fixed to the disc at their respective pivot points.

The photo & drawing for EN 593 double shaft wafer type butterfly valves.

Compared to one-piece through shaft design, the double shaft design minimizes interferences with the central part of the valve disc, providing better fluid flow characteristics (reduced flow resistance and pressure drop). Nevertheless, the double shaft butterfly valve has a more complex structure, resulting in higher production and assembly costs. Additionally, the size of double shaft butterfly valves is generally limited to DN300 or smaller and rubber seated soft sealing is required.

Material Specification & Technical Parameters

Mounting flange pad in accordance with ISO 5211 or MSS SP 102; Rated working pressure: 16 bar/250 psi; Rated working temperature: -10°C~80°C for NBR seat, -20°C~110°C for EPDM seat; Flange drilling shall be in accordance with EN 1092-1 PN10/PN16, ASME B16.1 Class 125, BS 10 Table D/E; FBE coatings interior and exterior.

Sizes & Dimensions