Large size Double Eccentric Butterfly valves to DN2500
A double offset butterfly valve called as DEX valve, Double Eccentric Butterfly valves, valve body seat is offset to the front side of the body, and the disc is offset to the front side of the shaft.it is applied in the raw water long distance transportation, water treatment, drinking water distribution projects.
| STANDARD | OPTION | |
| Design | EN 593 Double Flanged, Double Eccentric | |
| Nominal Sizes | DN 100 - DN2500 | 4“ to 100" |
| Pressure Rating | PN 10, PN 16, PN 25, | 150 PSI 150PSI 228PSI 350PSI |
| Medium | Potable water, raw water | Sea water |
| Face To Face | EN 558 – 1 SERIES 13 | EN 558 – 1 SERIES 14 |
| Flanges | EN1092-1 | ANSI B16.5; ASME B 16.47 Series A AWWA C207 |
| AS 2129 – AS4087; SABS 1123, Gramaphone grooved raised face flange | ||
| Material | ||
| Body | Ductile Iron | WCB, CF8, CF8M, DUPLEX SS2205 /2507 |
| Disc | Ductile Iron+Nickel Plated | Al-Ni bronze, CF8M, 4A, 5A |
| Sealing Ring | EPDM rubber | NBR, PTFE |
| Shaft | Stainless steel | 17-4PH,F51, F55 |
| Body Seat | 304 Stainless steel weld overlay & micro finished | Chrome nickel overlay & 316 & rubber lined, DUPLEX SS2205/2507 |
| Retaining Ring | 316 Stainless steel | ST 37 Carbon Steel, AI-Ni bronze Internal Fixings |
| External Fixings | Stainless steel | |
| Bearing Bush | Bronze + Delrin | NI-AL bronze + Delrin |
| Coating | Epoxy coated, min. 500 Microns thickness | Two pack epoxy, solvent free epoxy, coal tar epoxy Operation |
| Work Temperature | According to EN 1074 | |
| Colour | RAL 5005 | Ask for other colours |
| Closing Direction | Anticlockwise close | Clockwise |
| Operation | Manual by worm gearbox and handwheel | Electric, Pneumatic, Hydraulic, Actuator |
The advantages of double offest design
The first eccentricity (eL) brings the axis of rotation outside
the sealing axis. That’s why full circle sealing between body seat and sealing ring is achieved. The second eccentricity (e2) brings the axis of the disc from axis of the valve. By the help of second eccentricity the sealing ring is off seated after only a few degrees of movement at open direction. The purpose of the second eccentricity is to quickly relieve rubber seal compression in the area of the disc shafts to eliminate rubber “scuffing and abrasive wear”.
When the valve is open, the rubber is completely unstressed, so that no permanent impression is retained even if the valve remains open for years.
Good Performance of each main parts
Body
Streamline design and smooth finish of the body provides minimum resistance to flow.
Disc
Streamlined and low profiled disc including closed hubs ensuring higher kv values. Double offset disc design reduces seal wear and torque.
Sealing system
Sealing on seat face is ensured by an endless T profile resilient sealing ring which is held on the periphery of the disc by a retaining ring. In closed position the sealing ring is pressed against the conically shaped seat face of the body and provides safe sealing in either direction of flow. In opened position the sealing ring is completely unstressed due to the double eccentric disc design.
Retaining ring
The one piece retaining ring prevents sealing ring from rolling out. Sealing ring can be replaced easily at site without dismantling the valve disc and without requirement of any special tool.
Application:
Double eccentric butterfly valves are most often used in water supply applications below ground as an alternative to gate valves. When installing butterfly valves below ground a lower bury depth is required and typically, they are more cost-effective, especially in the large dimensions, compared to gate valves. They can of course also be used above ground.
Photos show of different double Eccentric Butterfly valves
large size butterfly valves with face to face length ISO5752 / EN558 Series 13
Butterfly valves with ISO5752/ EN558 Series 14, W.P. of PN16 PN25
Ebonited Butterlfy valves with fully lined on body and Disc, Hard rubber lined for sea water
