Diaphragm valve weir - DIAVAL Fig. W | Comeval

Diaphragm Valve DIAVAL Fig. W Weir Type

The DIAVAL Fig. W from Comeval is a linear motion, bidirectional diaphragm valve with a bolted bonnet and seatless body. The diaphragm acts as an isolation and sealing element, separating the medium from the operating mechanism. The weir type is used for flow isolation and can also function in throttling applications, with caution advised for small openings due to potential diaphragm/body erosion.

Technical Selection Data

• Sizes: up to DN300.
• Connections: flanged EN 1092-2 PN10/16 up to DN150, PN10 for DN200–DN300, optional ASA150 drilling. Threaded versions available in BSPP, BSPT, or NPT.
• Standards: EN 13397, EN 12516, EN 558 Series 1 / Series 7, EN 19, EN 12266-1 Rate A.
• Compliance: PED 2014/68/EU and Machinery Directive 2006/42/EC.

Pressure and Temperature

Operating limits depend on body, lining, and diaphragm materials. For ductile iron body, indicative: with rubber diaphragm PS 16 bar for DN10–50, 10 bar for DN65–150, 6 bar for DN200, 5 bar for DN250, and 4 bar for DN300. With PTFE diaphragm: PS 10 bar for DN10–125 and 6 bar for DN150. Final selection should be verified as a combination of pressure–temperature–chemical compatibility.

Materials and Sealing

Available diaphragms: Natural Rubber, EPDM, Butyl, NBR, Neoprene, Hypalon, Viton, Linatex, and PTFE-backed options like PTFE/EPDM, PTFE/Butyl, and PTFE/Viton. Body linings include hard rubber, soft rubber, butyl, EPDM, neoprene, Hypalon, PFA, FEP, ETFE, Halar, and Linatex.

Applications

Suitable for HVAC, water treatment, utility networks, lubrication, and industrial processes with corrosive or moderately abrasive fluids, when lining and diaphragm are selected for the specific medium.

Handling and Maintenance

Basic version with rising handwheel and position indicator. Pneumatic or electric actuators, limit switches, sealed bonnet, interlocking, and padlocking available. Maintenance focuses on diaphragm replacement and leakage inspection from witness hole.

FAQ

Is it used for flow regulation?
Yes, the weir type can operate in intermediate positions, but not extended near closure when abrasive or corrosive media are present.

When is it preferred over straight-through?
When better throttling control is required and not full free passage of solids. For high solid content, straight-through geometry is usually considered.